CN111905941B - A kind of control method of fan-shaped spray flow field - Google Patents

Abstract

The invention relates to a method for controlling a fan-shaped spray flow field, which specifically includes the following steps: (1) initially setting the parameters of the flow field when the nozzle sprays liquid under gas-liquid pressure and flow rate: z ₀ , z _n , 3σ(0 ,z ₀ ),

c(0), h(z ₀ ), k; (2) Calculate the distribution of the spray flow field: in the basic section of the jet, the spatial flow intensity distribution function is as follows:

Among them, Q(r, θ, z) is the spatial flow intensity distribution function at any point in the basic segment of the flow field; (3) Compare the difference between the spatial flow intensity distribution and the expected flow intensity; (4) Perform the spatial flow intensity distribution on the Adjustment: first replace the nozzle, then rotate the rotation angle of the nozzle around the x, y, and z axes, and finally increase or decrease the gas-liquid pressure and flow rate at the nozzle inlet until the difference between the spatial flow intensity distribution and the expected flow intensity distribution satisfies:

n is the number of small cubes.

Description

A kind of control method of fan-shaped spray flow field

technical field

The invention relates to the field of liquid coating, in particular to the control of the spray flow field of a fan-shaped nozzle.

Background technique

Atomized spraying is widely used in automobile industry, wood products processing industry, irrigation and other industries. In recent years, due to the needs of personalized customization, atomized spraying has been increasingly used on home decorations, clothing fabrics, posters and other objects. Due to the large difference in nozzle structure, under the action of different pressures and flow rates, different liquids eject different spray flow fields, which brings difficulties to the multi-nozzle combination layout. At present, most companies improve the uniform distribution of liquid on the sprayed object by continuously adjusting the pressure and flow through the nozzle inlet, the relative position between the nozzle and the sprayed object, and the relative position between the nozzle and the sprayed object. sex. With the continuous improvement of spraying requirements, only knowing the mathematical expression of the spatial distribution of the flow field under specific spraying process conditions can provide a basis for the multi-nozzle combination layout and provide convenience for the online control of the spray liquid volume.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a control method for the fan-shaped spray flow field; specifically, through the derivation of the plane flow distribution function and the spatial flow distribution function of the fan-shaped nozzle, the nozzle flow distribution is established, which is suitable for fan-shaped nozzles, circular The calculation of spray flow fields such as nozzles provides a mathematical basis for nozzle pressure control, flow control and multi-nozzle combined layout, and provides the possibility to achieve uniform spraying.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

A method for controlling a fan-shaped spray flow field, comprising the following steps:

(1) Initially set the nozzle to spray liquid under the gas-hydraulic pressure and flow (the extreme values of pressure and flow are determined by the hydraulic pipeline, nozzle structure and spray volume requirements) (select the appropriate nozzle according to the difference in liquid viscosity. Nozzle selection Appropriately, under the action of pressure, the liquid can be atomized into small droplets) The parameters of the flow field are as follows:

z ₀ , is the distance from the start of the basic section of the jet to the nozzle;

z _n , is the distance from the end of the basic section of the jet to the nozzle;

On the z=z ₀ section, in the effective injection area of the flow, the semi-major axis of the ellipse is 3σ(0, z ₀ );

On the z=z ₀ section, in the effective injection area of the flow, the short semi-axis of the ellipse is

c(0), where the azimuth angle θ is 0°, the slope of the outer contour of the flow field along the positive direction of the z-axis;

处的流量强度值h(z₀)；On the z=z ₀ section, through the section center

The flow intensity value at h(z ₀ );

k, the flow intensity of the jet central axis along the z-axis (that is, the axial direction of the jet central axis, the above "z=z ₀ " means "displacement on the z-axis"

z ₀ ”) anti-decay coefficient;

c(0)、h(z₀)、k数值大小均与喷嘴结构，喷嘴气液压力、流量、速度和质量比值，液体的成分、粘度、密度、表面张力等属性有关；受喷液体在一定的气、液压力作用下，经喷嘴出口，可分为射流初始段、射流基本段和射流消散段。其中，射流初始段的稳定性差，不具有工业使用价值；射流消散段距离喷口距离较远，其射流动压力难以达到所需要求；而处在射流基本段的流量场比较稳定，受喷液体雾化均匀，雾化层和周围空气也有较为明显的界限，具有实际应用意义；z ₀ , z _n , σ(0,z ₀ ),

The values of c(0), h(z ₀ ) and k are all related to the nozzle structure, nozzle gas-liquid pressure, flow rate, velocity and mass ratio, liquid composition, viscosity, density, surface tension and other properties; Under the action of the gas and hydraulic pressure, through the nozzle outlet, it can be divided into the initial section of the jet, the basic section of the jet and the dissipated section of the jet. Among them, the stability of the initial section of the jet is poor and has no industrial value; the dissipating section of the jet is far away from the nozzle, and its jet flow pressure is difficult to meet the required requirements; and the flow field in the basic section of the jet is relatively stable and is affected by the sprayed liquid mist. The atomization layer and the surrounding air also have obvious boundaries, which has practical application significance;

(2) Calculate the distribution of the spray flow field: (The calculation of each nozzle is the same. In the multi-nozzle flow field, the flow of different nozzles needs to be numerically superimposed) In the basic section of the jet, the polar coordinate function of the spatial flow intensity distribution function formula, as follows:

Among them, Q(r, θ, z) is the spatial flow intensity distribution function at any point in the basic segment of the flow field, and all symbols such as r, θ, z have the same meaning as before; that is, the distribution function of the spray flow field, the measurement of the nozzle in a specific After substituting the 7 flow field parameters when spraying a specific liquid under the gas-liquid pressure and flow rate, the spray flow field distribution can be obtained;

(3) Compare the difference between the spatial flow intensity distribution function and the expected flow intensity:

In the basic section of the jet, the effective jet area of the flow is divided into n small cubes (the value of n depends on the calculation accuracy requirements, and n takes a larger value when the calculation accuracy is higher); calculate the center positions of all the small cubes _The magnitude _of the flow intensity Q _c ( _r , _θ , _{z )} at the _{location of} the ₂ ,z ₂ ),...,Q _c (r _n ,θ _n ,z _n )}; set the expected flow intensity at the center of all small cubes to be Q _t (r,θ,z), its composition The set of is denoted as Q _t , namely: Q _t = {Q _t (r ₁ , θ ₁ , z ₁ ), Q _t (r ₂ , θ ₂ , z ₂ ),...,Q _t (r _n ,θ _n ,z _n )};

If the flow intensity Q _c and Q _t satisfy:

n为小方体数量；

n is the number of small cubes;

The control of the fan-shaped spray flow field is completed; otherwise, the spatial flow intensity distribution is adjusted until the control of the fan-shaped spray flow field is completed;

The adjustment of the spatial flow intensity distribution refers to:

(1) Replace the nozzle, specifically:

(1.1) When the expected flow field is circular, select a circular nozzle; when the expected flow field is elliptical, select a fan nozzle;

距离z轴原点P的距离(满足z₀≤z_x≤z_n)，P点位置为喷头出口中心；“z＝z_x截面”指沿z轴的任意平面)，流量有效喷射区域内，空间流量强度分布的流量场长、短半轴的比例为

与期望流量场长、短半轴的比例为

满足：(1.2) To adjust the circular nozzle or fan nozzle, you can use a table to record the ratio of the long and short semi-axes of the nozzle flow field of a series of different outlet shapes in advance, and query the corresponding Nozzle model, up to the basic section of the jet, on the z ₌ zx section ("z ₌ zx" means "the value of the jet center axis on the _z -axis is zx", that is, zx is the cross-section center of the _z -axis

The distance from the origin P of the z-axis (satisfying z ₀ ≤ z _{x ≤} z _n ), the position of point P is the center of the nozzle outlet; "z=z _x section" refers to any plane along the z-axis), within the effective injection area of flow, the space The ratio of the long and short semi-axes of the flow field of the flow intensity distribution is

The ratio of the long and short semi-axes to the expected flow field is

Satisfy:

Among them, a _c represents the semi-major axis of the flow field of the spatial flow intensity distribution, b _c represents the semi-short axis of the flow field of the spatial flow intensity distribution, a _t represents the semi-major axis of the expected flow field, and b _t represents the semi-axis of the expected flow field. axis;

When spraying requirements are different, different types of nozzles are selected to spray liquids with different properties, and the liquid incidence parameters such as pressure, speed, flow rate, and gas-liquid mass ratio at the nozzle inlet are adjusted accordingly. The gas-liquid pressure and flow parameters should be below the maximum working pressure and maximum flow allowed by the nozzle.

The liquid to be sprayed is not limited to water. According to different objects to be sprayed, spray liquids with different components, such as pigments and chemical reagents, are selected. The properties of liquids such as viscosity and surface tension vary greatly. When the liquid properties are easily affected by temperature, the change of the liquid properties also affects the spatial flow intensity of the spray flow field.

After adjusting the nozzle to meet the above requirements, a comparison of the difference between the spatial flow intensity distribution function and the expected flow intensity can be carried out. If the difference between the two requirements is met, no further adjustment is necessary, that is, the control of the fan-shaped spray flow field is completed; If satisfied, continue to adjust:

(2) Taking the point P of the nozzle outlet center as the rotation center, the rotation angle of the rotating nozzle around the x, y, and z axes, that is, the order of adjustment around the rotation axis is z→y→x, until the basic section of the jet, the flow rate is effectively sprayed In the area, the flow field of the spatial flow intensity distribution is in the same direction as the expected flow field; when the rotation angles of the nozzles around the x, y, and z axes are adjusted to meet the above requirements, a difference between the spatial flow intensity distribution function and the expected flow intensity can be performed. If the difference requirements between the two are met, no further adjustment is necessary, that is, the control of the fan-shaped spray flow field is completed; if not, continue to adjust:

(3) Increase or decrease the gas-liquid pressure and flow rate at the nozzle inlet until the difference between the spatial flow intensity distribution and the expected flow intensity distribution meets the requirements.

As the preferred technical solution:

The above-mentioned control method of a fan-shaped spray flow field, the calculation method of the rotation angle of the rotating nozzle around the x, y, and z axes is:

(1) Suppose the spatial position of the desired flow field can be represented by a 3×3 matrix B, which is parallel to the nozzle local coordinate axes x _i , y _i , and _zi , and has the same size and the same direction, that is,

两两正交且其行列式的值为1，则A^-1＝A^T；Let the spatial position of the flow field of the spatial flow intensity distribution be

If they are orthogonal to each other and the value of their determinant is 1, then A ^-1 =A ^T ;

(2) Set the rotation matrix R, so that B=AR, then R=A ^-1 B;

(3) According to A ^-1 =A ^T , R = A ^-1 B = A ^T B, then:

Among them, the spatial position A can be obtained by the attitude sensor installed on the nozzle, which can directly read the position value, and the spatial position B is given by the desired position;

(4) The order of adjustment around the rotation axis is z→y→x, and the corresponding adjustment angles are set as γ, β, and α; then the rotation matrix R is:

Among them, R _zyx is the space rotation matrix formed by rotating around the z, y, and x axes in turn using a right-handed coordinate system; Rotz, Rot y, and Rot x are formed by rotating γ, β, and α around the z, y, and x axes, respectively. The base rotation matrix of ;

(5) Simultaneously connect A ^T B and matrix R to solve γ, β, and α, that is, rotate the nozzle around the z-axis by γ, around the y-axis by β, and rotate around the x-axis by α, and then the nozzle can be moved from the spatial position A. Adjust to spatial position B.

和c(0)，使用50mm定焦镜头相机标定图像像素与实际尺寸之间的关系后，从所拍摄的流量场图像上计算获得。A control method for the fan-shaped spray flow field as described above, the geometric parameters z ₀ , z _n , σ(0, z ₀ ),

and c(0), calculated from the captured flow field image after calibrating the relationship between image pixels and actual size using a 50mm fixed-focus lens camera.

In the above-mentioned control method of the fan-shaped spray flow field, h(z ₀ ) and k belong to the flow field mechanics parameters, which are measured using a pitot tube.

The above-mentioned control method of a fan-shaped spray flow field, the specific process of calculating the spray flow field distribution is:

(2.1) Establish a plane polar coordinate system, and obtain the polar coordinate function formula of the plane flow intensity function;

截面几何中心至喷口的距离为z_x(指截面几何中心

至喷嘴出口中心P的距离)，且z₀≤z_x≤z_n；In the basic section of the jet, the jet section perpendicular to the jet beam axis is arbitrarily intercepted, and the plane flow intensity function in any direction in the jet section and its functional formula in the plane polar coordinate system are obtained; where the geometric center of the section is

The distance from the geometric center of the section to the nozzle is z _x (referring to the geometric center of the section

distance to the nozzle outlet center P), and z ₀ ≤z _x ≤z _n ;

的任意一条直线，与x轴正方向之间的夹角(即直线的方位角)为θ(θ∈[0,π])；在此直线上，射流流量强度分布符合正态分布规律，其流量强度函数为：Cross-section geometric center

The angle between any straight line and the positive direction of the x-axis (that is, the azimuth angle of the straight line) is θ(θ∈[0,π]); on this straight line, the jet flow intensity distribution conforms to the normal distribution law, and its The flow intensity function is:

-∞＜m＜+∞；

-∞＜m＜+∞;

m、θ是参变量，与射流截面内的坐标变量x、y之间存在如下关系：Among them, e is the Euler number with a value of about 2.71828; Γ is the magnification of the flow intensity function formula; μ is the mathematical expectation value in probability statistics, and its mathematical meaning is f(μ)=[f(m)] _max ; σ is the flow intensity variance ("σ" represents the flow intensity variance. Although "σ" is used with the previous "3σ rule", the two units are different, but according to the normal distribution 3σ rule, because the two are numerically related. , the same symbol is used in the probability), the value is related to the distance z _x from the center of the section to the nozzle, and the azimuth angle θ, denoted as

m and θ are parameters, which have the following relationship with the coordinate variables x and y in the jet section:

且与x轴正方向成θ的直线上任意一点的平面流量强度函数的极坐标函数式为：Using the relationship between the parameter variables and the coordinate variables, the flow intensity function is rewritten into the form in the plane polar coordinate system, then the point

And the polar coordinate function formula of the plane flow intensity function at any point on the straight line that forms θ with the positive direction of the x-axis is:

(2.2) After the uniqueness test and the non-negativity test, correct the polar coordinate function formula of the plane flow intensity function;

In the plane polar coordinate system, in order to ensure that the flow intensity value of each point in the basic section of the jet is unique and non-negative, the polar coordinate function formula of the plane flow intensity function needs to be modified as follows:

是截面上任意一点在平面极坐标系下，经唯一性、非负性检验修正后的平面流量强度函数；

为截面几何中心

处的流量强度值，对于一个确定的平面来说是常数；

是

在其变量取值范围内的最小值，满足

in,

is the plane flow intensity function corrected by the uniqueness and non-negativity test at any point on the section in the plane polar coordinate system;

is the geometric center of the section

The flow intensity value at , is constant for a certain plane;

Yes

The minimum value within the range of its variable values, satisfying

(2.3) The 3σ rule is adopted to establish the boundary of the jet section and improve the polar coordinate function formula of the plane flow intensity function;

According to the rate of change of the effective jet area of the flow field along the z-axis on different sections, the contour boundary in the basic segment of the jet flow field is extracted;

由不同长度的流量强度射线旋转而成；由(2.1)可知，射线上的流量强度分布符合正态分布，根据3σ法则，椭圆边界上任意一点至截面几何中心

的距离为

则

可表示为：In the basic section of the jet, the flow intensity distribution shape on any jet section can be regarded as an ellipse family centered on the jet axis, and the ellipse family can be regarded as passing through its center.

It is formed by the rotation of flux intensity rays of different lengths; from (2.1), it can be seen that the flux intensity distribution on the rays conforms to the normal distribution. According to the 3σ rule, any point on the ellipse boundary to the geometric center of the section

The distance is

but

can be expressed as:

分别为z＝z_x截面上，流量喷射区域椭圆长半轴、短半轴的

且

in,

On the z=z _x section, the major semi-axis and minor semi-axis of the ellipse in the flow jet area are respectively

and

After adopting the 3σ rule, the effective injection area is considered, and the value range of r in the plane flow intensity function is limited. Then the polar coordinate function formula of the plane flow intensity function defined by the flow boundary is:

是截面上任意一点在平面极坐标系下，经唯一性、非负性检验后，在有效喷射区域内的平面流量强度分布函数；r为截面上任意一点至截面几何中心的距离(r_max＝3σ(θ))；in,

is the plane flow intensity distribution function of any point on the section in the plane polar coordinate system, after the uniqueness and non-negativity test, in the effective injection area; r is the distance from any point on the section to the geometric center of the section (r _max = 3σ(θ));

(2.4) In the basic section of the jet, the elliptical shapes of the effective injection area of the section at different positions from the nozzle are similar, and the width of the effective injection area of the section increases linearly along the positive direction of the z-axis, namely:

是z＝z₀截面上，与x轴正方向成不同角度的直线上的流量强度分布方差，与σ(θ,z₀)含义相同，即有

推广到射流基本段内任意截面上，均有σ_z(θ)＝σ(θ,z)。Among them, c(θ) is the rate of change of the effective jet area width of the section along the z-axis, which is related to the azimuth angle θ;

is the variance of the flow intensity distribution on the straight line at different angles to the positive direction of the x-axis on the z=z ₀ section, which has the same meaning as σ(θ, z ₀ ), that is, there is

Generalized to any section in the basic section of the jet, there is σ _z (θ)=σ(θ, z).

以及方位角θ为0°时流量场外轮廓沿z轴正方向的斜率c(0)，获得任意方位角θ上的流量有效喷射区域的变化率c(θ)：Extract the flow intensity distribution variance σ(0,z ₀ ) on the ellipse major semi-axis and minor semi-axis of the effective injection area of the flow on the z=z ₀ section,

And the slope c(0) of the outer contour of the flow field along the positive direction of the z-axis when the azimuth angle θ is 0°, the change rate c(θ) of the effective injection area of the flow rate at any azimuth angle θ is obtained:

均与喷嘴结构、喷嘴入口的气液压力及其比值、液体的粘度、液体的密度和液体的表面张力有关。Among them, c(0), σ(0, z ₀ ),

It is related to the nozzle structure, the gas-liquid pressure at the nozzle inlet and its ratio, the viscosity of the liquid, the density of the liquid and the surface tension of the liquid.

(2.5) According to the attenuation law of the flow intensity at the center of the jet along the z-axis, the flow intensity function on the central axis of the jet is obtained, and then the spatial flow intensity distribution function is obtained; the flow intensity at the center of the jet decreases in a hyperbolic form along the z-axis, namely:

Among them, the larger the value of k, the slower the attenuation speed of the flow intensity along the z-axis of the jet center axis; the smaller the k value, the faster the attenuation speed of the flow intensity along the z-axis of the jet center axis;

Q _z (0, θ) represents the flow intensity function at the azimuth angle θ on the section that passes through the central axis of the jet and is perpendicular to the z-axis, written in the form of Q(0, θ, z), abbreviated as h _z or h ( z), that is, Q _z (0, θ) = Q (0, θ, z) = h _z = h (z); then through the central axis of the jet, on the z = z ₀ section, the flow intensity at the azimuth angle θ The function is

That is:

射流空间流量强度分布函数的极坐标函数式为：Combined with the polar coordinate function of the plane flow intensity function defined by the flow boundary in (2.3)

The polar coordinate function formula of the jet spatial flow intensity distribution function is:

A method for controlling a fan-shaped spray flow field as described above, the reducing the gas-liquid pressure and flow rate at the nozzle inlet means that when Q _c -Q _t ≥ 1×10 ^-3 , simultaneously reducing the gas-liquid pressure at the nozzle inlet Hydraulic pressure and flow rate, then in the basic section of the jet, the flow intensity set Q _c at the center of each small cube in the effective flow jet area decreases; the increase in the gas-liquid pressure and flow rate at the nozzle inlet refers to when Q When _c -Q _t <1×10 ^-3 , increase the gas-liquid pressure and flow rate at the nozzle inlet at the same time, then in the basic section of the jet, the flow intensity set Q _c at the center of each small cube in the effective flow jet area increases. big.

beneficial effect

(1) A method for controlling the spray flow field of a fan-shaped nozzle of the present invention, by controlling the plane flow intensity distribution on different sections and different azimuth angles in the basic section of the jet, the uniqueness and non-negativity of the flow function value, the flow rate at the center of the jet The attenuation law of the intensity is comprehensively considered, and the spatial flow intensity distribution function of the spray flow field is obtained;

(2) A method for controlling the spray flow field of a fan-shaped nozzle of the present invention only needs to measure seven undetermined coefficients related to the nozzle structure, nozzle gas-liquid pressure, flow rate, velocity and mass ratio, and liquid properties, and then the nozzle can be obtained. Spatial flow intensity distribution function under specific injection parameters;

(3) A method for controlling the spray flow field of a fan-shaped nozzle of the present invention, through the derivation of the plane flow intensity distribution function and the spatial flow intensity distribution function of the fan-shaped nozzle, the established nozzle flow distribution is suitable for fan-shaped nozzles, circular nozzles flow field calculation;

(4) It provides a mathematical basis for nozzle pressure control, flow control and nozzle layout optimization, and makes it possible to achieve uniform spraying.

Description of drawings

Figure 1 is a schematic diagram of the nozzle flow field;

Figure 2 is a schematic diagram of flow intensity distribution in any section of the basic section of the jet; wherein, (a) is the position information of the basic section of the jet, and (b) is a schematic diagram of the flow intensity distribution in any direction in the section A-A;

Figure 3 is a schematic diagram of the long and short semi-axes of the ellipse in the effective jetting area of the flow in the jet flow section that is perpendicular to the z-axis of the jet beam axis in the basic section of the jet shown in Figures 1 to 2;

Fig. 4 is a schematic diagram of the measurement of geometric constants; wherein, (a) is a schematic diagram of the measurement of geometric constants corresponding to the short semi-axis of the ellipse, and (b) is a schematic diagram of the measurement of the geometric constants corresponding to the orientation of the major semi-axis of the ellipse;

Figure 5 is a schematic diagram of measuring the mechanical constants of flow field by using a pitot tube; wherein, 1- nozzle, 2- slide rail, 3- slider, 4- pitot tube, 5- orifice plate;

c(0)＝0.3；k＝1；h(z₀)＝100L/(s*m²)；Figure 6 is the distribution diagram of the initial flow field on the spray receiving surface when the spray receiving surface is 0.4m away from the nozzle outlet and the nozzle axis x, y, and z axes are simultaneously rotated by 20°; among them, the initial settings of the seven constants of the flow field are: : z ₀ =0.15m; z _n =0.4m; 3σ(0,z ₀ )=0.12m,

c(0)=0.3; k=1; h(z ₀ )=100L/(s*m ² );

时对应的受喷面上的流量场分布图，(b)为仅改变外轮廓初始斜率，即c(0)＝0.5时对应的受喷面上的流量场分布图，(c)为仅改变中心轴流强抗衰减系数，即k＝0.5时对应的受喷面上的流量场分布图，(d)为仅改变中心轴初始流强度，即h(z₀)＝85L/(s*m²)时对应的受喷面上的流量场分布图。Fig. 7 is the flow field distribution diagram on the spray surface after changing some parameters in Fig. 6, in which, (a) is only changing the ratio of the long and short semi-axes, that is, 3σ(0,z ₀ )=0.15m,

The flow field distribution on the spray receiving surface corresponding to , (b) only changes the initial slope of the outer contour, that is, the flow field distribution on the spray receiving surface corresponding to c(0)=0.5, (c) only changes The anti-attenuation coefficient of the central axial flow intensity, that is, the flow field distribution on the sprayed surface corresponding to k=0.5, (d) only changes the initial flow intensity of the central axial flow, that is, h(z ₀ )=85L/(s*m ² ), the flow field distribution map on the corresponding spray surface.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

A method for controlling a fan-shaped spray flow field, comprising the following steps:

(1) The flow field ejected by the nozzle is a non-submerged free jet, which can be roughly divided into an initial section, a basic section and a dissipation section (as shown in Figure 1). Among them, (a) is the position information of the basic section of the jet, (b) is the schematic diagram of the flow intensity distribution in any direction in the section A-A; in the plane polar coordinate system, the schematic diagram of the geometric size of the effective jet area of the section A-A flow field is shown in Figure 3 shown;

(2) Calculate the distribution of spray flow field:

(2.1) Establish a plane polar coordinate system to obtain a plane flow intensity function;

截面中心至喷口的距离为z_x，且z₀≤z_x≤z_n；The jet section perpendicular to the jet beam axis is arbitrarily intercepted in the basic section of the jet, and the plane flow intensity function in any direction in the jet section and its functional formula in the plane polar coordinate system are obtained; where the geometric center of the section is

The distance from the center of the section to the nozzle is z _x , and z ₀ ≤z _x ≤z _n ;

的任意一条直线，与x轴正方向之间的夹角(即直线的方位角)为θ(θ∈[0,π])；在此直线上，射流流量强度分布符合正态分布规律，其流量强度函数为：Cross-section geometric center

The angle between any straight line and the positive direction of the x-axis (that is, the azimuth angle of the straight line) is θ(θ∈[0,π]); on this straight line, the jet flow intensity distribution conforms to the normal distribution law, and its The flow intensity function is:

-∞＜m＜+∞；

-∞＜m＜+∞;

m、θ是参变量，与射流截面内的坐标变量x、y之间存在如下关系：Among them, e is the Euler number with a value of about 2.71828; Γ is the magnification of the flow intensity function formula; μ is the mathematical expectation value in probability statistics, and its mathematical meaning is f(μ)=[f(m)] _max ; σ is the flow intensity variance, the value is related to the distance z _x from the geometric center of the section to the nozzle, and the azimuth angle θ, denoted as

m and θ are parameters, which have the following relationship with the coordinate variables x and y in the jet section:

Using the relationship between the parameter variables and the coordinate variables, the flow intensity function is rewritten into the form in the plane polar coordinate system, then the plane flow intensity function is:

(2.2) After the uniqueness test and the non-negativity test, correct the plane flow intensity function;

In the plane polar coordinate system, in order to ensure that the flow intensity value of each point in the basic section of the jet is unique and non-negative, the following corrections should be made to the plane flow intensity function:

是截面上任意一点在平面极坐标系下，经唯一性、非负性检验修正后的平面流量强度函数；

为截面几何中心

处的流量强度值；

是

在其变量取值范围内的最小值，满足

In the formula,

is the plane flow intensity function corrected by the uniqueness and non-negativity test at any point on the section in the plane polar coordinate system;

is the geometric center of the section

The flow intensity value at ;

Yes

The minimum value within the range of its variable values, satisfying

(2.3) The 3σ rule is used to establish the boundary of the jet section and improve the plane flow intensity function;

的距离为

则

可表示为：In the basic section of the jet, the flow intensity distribution shape on any jet section can be regarded as an ellipse family with the jet axis as the center, and any point on the ellipse boundary to the geometric center of the section.

The distance is

but

can be expressed as:

分别为z＝z_x截面上，流量喷射区域椭圆长半轴、短半轴的

且

in,

On the z=z _x section, the major semi-axis and minor semi-axis of the ellipse in the flow jet area are respectively

and

Then the plane flow intensity function defined by the flow boundary is:

是截面上任意一点在平面极坐标系下，经唯一性、非负性检验后，在有效喷射区域内的平面流量强度分布函数；r为截面上任意一点至截面几何中心的距离，其最大值r_max＝3σ(θ)；in,

is the plane flow intensity distribution function of any point on the section in the plane polar coordinate system, after the uniqueness and non-negativity test, in the effective injection area; r is the distance from any point on the section to the geometric center of the section, and its maximum value r _max =3σ(θ);

(2.4) In the basic section of the jet, the elliptical shapes of the effective injection area of the section at different positions from the nozzle are similar, and the width of the effective injection area of the section increases linearly along the positive direction of the z-axis, namely:

是z＝z₀截面上，与x轴正方向成不同角度的直线上的流量强度分布方差，与σ(θ,z₀)含义相同，即有

σ_z(θ)＝σ(θ,z)。Among them, c(θ) is the rate of change of the effective jet area width of the section along the z-axis, which is related to the azimuth angle θ;

is the variance of the flow intensity distribution on the straight line at different angles to the positive direction of the x-axis on the z=z ₀ section, which has the same meaning as σ(θ, z ₀ ), that is, there is

σ _z (θ)=σ(θ, z).

以及方位角θ为0°时流量场外轮廓沿z轴正方向的斜率c(0)，获得任意方位角θ上的流量有效喷射区域的变化率c(θ)：Extract the flow intensity distribution variance σ(0,z ₀ ) on the ellipse major semi-axis and minor semi-axis of the effective injection area of the flow on the z=z ₀ section,

And the slope c(0) of the outer contour of the flow field along the positive direction of the z-axis when the azimuth angle θ is 0°, the change rate c(θ) of the effective injection area of the flow rate at any azimuth angle θ is obtained:

均与喷嘴结构、喷嘴入口的气液压力及其比值、液体的粘度、液体的密度和液体的表面张力有关。Among them, c(0), σ(0, z ₀ ),

It is related to the nozzle structure, the gas-liquid pressure at the nozzle inlet and its ratio, the viscosity of the liquid, the density of the liquid and the surface tension of the liquid.

(2.5) According to the attenuation law of the flow intensity at the center of the jet along the z-axis, the flow intensity function on the central axis of the jet is obtained, and then the spatial flow intensity distribution function is obtained; the flow intensity at the center of the jet decreases in a hyperbolic form along the z-axis, namely:

Among them, the larger the value of k, the slower the attenuation speed of the flow intensity along the z-axis of the jet center axis; the smaller the k value, the faster the attenuation speed of the flow intensity along the z-axis of the jet center axis;

Q _z (0, θ) represents the flow intensity function at the azimuth angle θ on the section that passes through the central axis of the jet and is perpendicular to the z-axis, written in the form of Q(0, θ, z), abbreviated as h _z or h ( z), that is, Q _z (0, θ) = Q (0, θ, z) = h _z = h (z); then through the central axis of the jet, on the z = z ₀ section, the flow intensity at the azimuth angle θ The function is

That is:

则获得空间流量强度分布函数为：In combination with (2.3)

Then the spatial flow intensity distribution function is obtained as:

Among them, Q(r, θ, z) is the spatial flow intensity distribution function at any point in the basic segment of the flow field.

The above spatial flow intensity distribution function is applied to the case, that is, the Japanese Meiji A-100 pneumatic atomizing nozzle is used; the initial parameters of the nozzle are set as follows: the distance between the outlet and the sprayed surface is 0.4m, the nozzle axis x, y, The z-axis rotates 20° at the same time; the nozzle inlet pressure is 0.3MPa, and the hydraulic pressure is 0.2MPa; the liquid formula is a mixture of 2.0wt% sodium alginate, 5.0wt% urea, 2.0wt% sodium bicarbonate and 91.0wt% water ( Under normal temperature, this mixed liquid viscosity 620CP) carries out the control of spray flow field; Concrete process is as follows:

其测量原理如图4(a)所示；使用50mm定焦镜头相机标定图像像素与实际尺寸之间的关系后，从所拍摄的流量场图像上计算获得σ(0,z₀)和c(0)，其测量原理如图4(b)所示；使用皮托管进行测定h(z₀)和k，如图5所示，将喷头1竖直固定，在喷头下方放置一块能够上下滑动的孔板5，孔板上的开口位于其几何中心处，使之与滑块3固连，滑轨2上有刻度标识，能够准确地知道当前孔板与喷头出口之间的竖直距离。把皮托管4的接口插入孔板内孔中，让管口开口方向与z轴相反。在z₀截面中心处测量其流量强度，所得值即为h(z₀)。接着，将z₀与z_n之间分为5等份，并在每个等分点测量一次流量强度，把流量强度和射流轴向距离之间的关系在直角坐标系中绘制成离散的点，用双曲线函数对图像进行拟合，便能获得抗衰减系数k。(1) After calibrating the relationship between image pixels and actual size using a 50mm fixed-focus lens camera, calculate and obtain z ₀ , z _n and z 0 from the captured flow field image.

The measurement principle is shown in Figure 4(a); after using a 50mm fixed-focus lens camera to calibrate the relationship between image pixels and actual size, σ(0,z ₀ ) and c( 0), and its measurement principle is shown in Figure 4(b); use a pitot tube to measure h(z ₀ ) and k, as shown in Figure 5, fix the nozzle 1 vertically, and place a piece that can slide up and down under the nozzle Orifice plate 5, the opening on the orifice plate is located at its geometric center, so that it is fixedly connected with the slider 3, and there is a scale mark on the slide rail 2, which can accurately know the current vertical distance between the orifice plate and the nozzle outlet. Insert the port of the pitot tube 4 into the inner hole of the orifice plate so that the opening direction of the orifice is opposite to the z-axis. The flow intensity is measured at the center of the z ₀ section, and the resulting value is h(z ₀ ). Next, divide z ₀ and z _n into 5 equal parts, and measure the flow intensity at each aliquot point, and draw the relationship between the flow intensity and the axial distance of the jet as discrete points in the Cartesian coordinate system , and the image is fitted with a hyperbolic function to obtain the anti-attenuation coefficient k.

The specific parameters are:

z ₀ =0.15m, which is the distance from the start of the basic section of the jet to the nozzle;

z _n = 0.4m, which is the distance from the end of the basic section of the jet to the nozzle;

On the z=z ₀ section, in the effective injection area of the flow, the major semi-axis of the ellipse is 3σ(0, z ₀ )=0.12m;

On the z=z ₀ section, in the effective injection area of the flow, the short semi-axis of the ellipse is

When the azimuth angle θ is 0°, the slope of the outer contour of the flow field along the positive direction of the z-axis is c(0)=0.3;

On the z=z ₀ section, the flow intensity value at the geometric center O _z0 of the section h(z ₀ )=100L/(s*m ² );

The anti-attenuation coefficient k=1 of the flow intensity along the z-axis of the central axis of the jet;

Further determine the initial flow field distribution on the sprayed surface as shown in Figure 6;

时对应的受喷面上的流量场分布图，(b)为仅改变外轮廓初始斜率，即c(0)＝0.5时对应的受喷面上的流量场分布图，(c)为仅改变中心轴流强抗衰减系数，即k＝0.5时对应的受喷面上的流量场分布图，(d)为仅改变中心轴初始流强度，即h(z₀)＝85L/(s*m²)时对应的受喷面上的流量场分布图。Moreover, when the above parameters are adjusted, the flow field distribution on the corresponding sprayed surface changes, as shown in Figure 7, where (a) only changes the ratio of the long and short semi-axes, that is, 3σ(0,z ₀ )=0.15m,

The flow field distribution on the spray receiving surface corresponding to , (b) only changes the initial slope of the outer contour, that is, the flow field distribution on the spray receiving surface corresponding to c(0)=0.5, (c) only changes The anti-attenuation coefficient of the central axial flow intensity, that is, the flow field distribution on the sprayed surface corresponding to k=0.5, (d) only changes the initial flow intensity of the central axial flow, that is, h(z ₀ )=85L/(s*m ² ), the flow field distribution map on the corresponding spray surface.

(2) Compare the difference between the spatial flow intensity distribution and the expected flow intensity:

In the basic section of the jet, on the z=z _x section, the effective jetting area of the flow is divided into n small cubes; when the spraying object is a car or fabric, the spraying requirement is very high, and the value of n is greater than 100; the spraying object is a building When the spraying object is a mechanical device frame, the spraying requirements are general, and the value of n is 10-50; calculate the flow intensity Q _c (r, θ, z at the center of all small cubes) ), the set composed of it is denoted as Q _c , namely: Q _c ={Q _c (r ₁ ,θ ₁ ,z ₁ ),Q _c (r ₂ ,θ ₂ ,z ₂ ),...,Q _c ( r _n , θ _n , z _n )}; set the expected flow intensity at the center of all cubes to be Q _t (r, θ, z), and the set composed of them is denoted as Q _t , namely: Q _t = { Q _t (r ₁ ,θ ₁ ,z ₁ ),Q _t ( _{r 2} ,θ ₂ ,z ₂ ),...,Q _t (rn ,θ _n ,z _n )};

If the flow intensity Q _c and Q _t satisfy:

n为小方体数量；

n is the number of small cubes;

Then, the difference between the spatial flow intensity distribution and the expected flow intensity distribution does not meet the requirements;

(3) The spatial flow intensity distribution needs to be adjusted:

(3.1) Replace the nozzle, specifically:

(3.1.1) When the expected flow field is circular, select a circular nozzle; when the expected flow field is elliptical, select a fan nozzle;

与期望流量场长、短半轴的比例为

满足：(3.1.2) To adjust the circular nozzle or fan-shaped nozzle, you can use a table to record the ratio of the long and short semi-axis of the nozzle flow field of a series of different outlet shapes in advance. Corresponding nozzle model, up to the basic section of the jet, on the z = z _x section, in the effective injection area of the flow, the ratio of the long and short semi-axes of the flow field of the spatial flow intensity distribution is:

The ratio of the long and short semi-axes to the expected flow field is

Satisfy:

Among them, a _c represents the semi-major axis of the flow field of the spatial flow intensity distribution, b _c represents the semi-short axis of the flow field of the spatial flow intensity distribution, a _t represents the semi-major axis of the expected flow field, and b _t represents the semi-axis of the expected flow field. axis;

After adjusting the nozzle to meet the above requirements, a comparison of the difference between the spatial flow intensity distribution function and the expected flow intensity can be carried out. If the difference between the two requirements is met, no further adjustment is necessary, that is, the control of the fan-shaped spray flow field is completed; If satisfied, continue to adjust:

(3.2) The rotation angle of the rotating flow field around the x, y, and z axes, that is, the order of adjustment around the rotating axis is z→y→x until the basic section of the jet, on the z=z _x section, the effective flow area of the jet The long and short semi-axes of the flow field of the spatial flow intensity distribution are respectively parallel to the long and short semi-axes of the expected flow field;

The rotation angle of the rotating nozzle around the x, y, and z axes is calculated as:

(3.2.1) It is assumed that the spatial position of the desired flow field can be represented by a 3×3 matrix B, which is parallel to the nozzle local coordinate axes x _i , _yi , and _zi , and has the same size and the same direction, that is,

则A^-1＝A^T；Let the spatial position of the flow field of the spatial flow intensity distribution be

Then A ^-1 =A ^T ;

(3.2.2) Set the rotation matrix R, so that B=AR, then R=A ^-1 B;

(3.2.3) According to A ^-1 =A ^T , R = A ^-1 B = A ^T B, then:

Among them, the spatial position A can be obtained by the attitude sensor installed on the nozzle, and the spatial position B is given by the desired position;

(3.2.4) Set the order of adjustment around the rotation axis as z→y→x, and the corresponding adjustment angles are γ, β, α; then the rotation matrix R is:

Among them, R _zyx is the space rotation matrix formed by rotating around the z, y, and x axes in turn using a right-handed coordinate system; Rotz, Rot y, and Rot x are formed by rotating γ, β, and α around the z, y, and x axes, respectively. The base rotation matrix of ;

(3.2.5) Simultaneously combine A ^T B and matrix R to solve γ, β, α, that is, rotate the nozzle around the z-axis by γ, around the y-axis by β, and rotate around the x-axis in turn, then the nozzle can be removed from the space Position A is adjusted to spatial position B;

After adjusting the rotation angles of the nozzles around the x, y, and z axes to meet the above requirements, a comparison of the difference between the spatial flow intensity distribution and the expected flow intensity can be performed. Complete the control of the fan-shaped spray flow field; if it is not satisfied, continue to adjust:

(3.3) Increase or decrease the gas-liquid pressure and flow at the nozzle inlet:

When Q _c -Q _t <1×10 ^-3 , the gas-liquid pressure and flow rate at the nozzle inlet are increased at the same time, then in the basic section of the jet flow, the flow intensity set at the center of each small cube in the effective flow jet area Q _c increases until the difference between the spatial flow intensity distribution and the expected flow intensity distribution meets the requirements;

When Q _c -Q _t ≥ 1×10 ^-3 , the gas-liquid pressure and flow rate at the nozzle inlet are reduced at the same time, and the flow intensity set at the center of each small cube in the effective flow jet area in the basic section of the jet flow Q _c decreases until the difference between the spatial flow intensity distribution and the expected flow intensity distribution meets the requirements;

Satisfying the requirements refers to the flow intensity Q _c and Q _t :

n为小方体数量；

n is the number of small cubes;

That is, the control of the fan-shaped spray flow field is completed.

Claims (6)

1. A control method of a fan-shaped spray flow field is characterized by comprising the following steps:

(1) initially setting the nozzle under gas-liquid pressure and flow, and setting the parameters of a flow field when the nozzle sprays liquid as follows:

z₀the distance from the beginning of the jet basic section to the nozzle;

z_nthe distance from the termination of the jet basic section to the jet orifice;

z＝z₀on the cross section, in the effective jet area of the flow, the ellipse major semiaxis is 3 sigma (0, z)₀)；

z＝z₀On the cross section, in the effective flow injection area, the elliptical short semi-axis

c (0), the azimuth angle theta is 0 degree, and the slope of the outline of the flow field along the positive direction of the z axis;

z＝z₀on the cross section, passing through the center O of the cross section_z0Flow intensity value h (z) of₀)；

k, the anti-attenuation coefficient of the flux intensity of the central axis of the jet along the z-axis;

(2) calculating the spray flow field distribution: in the jet fundamental section, the spatial flow intensity distribution function is as follows:

wherein Q (r, theta, z) is a spatial flow intensity distribution function of any point in the basic segment of the flow field; r is the distance from any point on the section to the geometric center of the section;

(3) comparing the difference of the spatial flow intensity distribution with the expected flow intensity:

in the jet basic section, dividing the effective flow injection area into n small cubes; calculating the flow intensity Q of the center positions of all the cubes_c(r, θ, z), the set of which is denoted Q_cNamely: q_c＝{Q_c(r₁,θ₁,z₁),Q_c(r₂,θ₂,z₂),...,Q_c(r_n,θ_n,z_n) }; let the expected flow intensity at the center of all the cubes be Q_t(r, θ, z), the set of which is denoted Q_tNamely: q_t＝{Q_t(r₁,θ₁,z₁),Q_t(r₂,θ₂,z₂),...,Q_t(r_n,θ_n,z_n)}；

If the flow intensity Q_cAnd Q_tSatisfies the following conditions:

n is the number of small cubes;

then the control of the fan-shaped spray flow field is finished; otherwise, adjusting the spatial flow intensity distribution until the control of the fan-shaped spray flow field is finished;

the adjusting the spatial flow intensity distribution refers to:

(1) the nozzle replacement specifically comprises:

(1.1) when the expected flow field is circular, selecting a circular nozzle; when the desired flow field is elliptical, selecting a fan nozzle;

(1.2) adjusting the circular nozzle or the fan-shaped nozzle until the jet flow is in the basic section, wherein z is equal to z_xOn the cross section, in the effective flow jet area, the ratio of the length of the flow field and the short half shaft of the space flow intensity distribution is

The ratio of the desired flow field length to the half-axis of the desired flow field length is

Satisfies the following conditions:

wherein, a_cFlow field length semiaxis, b, representing spatial flow intensity distribution_cFlow field minor semiaxis, a, representing spatial flow intensity distribution_tThe longer half-axis representing the desired flow field, b_tA minor semi-axis representing the desired flow field;

(2) rotating angles of the rotating nozzle around x, y and z axes, namely the sequence of regulation around the rotating shaft is z → y → x in sequence, until the flow field of space flow intensity distribution is the same as the direction of the expected flow field in the effective flow injection area in the jet flow basic section;

(3) and increasing or decreasing the gas-liquid pressure and the flow rate of the nozzle inlet until the difference between the space flow rate intensity distribution and the expected flow rate intensity distribution meets the requirement.

2. The method as claimed in claim 1, wherein the rotation angle of the rotating nozzle around the x, y and z axes is calculated as follows:

(1) the spatial position of the desired flow field may be represented by a 3 x 3 matrix B, and associated with the local axis x of the nozzle_i、y_i、z_iParallel, and of equal size and in the same direction, i.e.

The spatial position of the flow field with the spatial flow intensity distribution is

Then A is^-1＝A^T；

(2) Let the rotation matrix R, let B equal AR, then R equal A^-1B；

(3) According to A^-1＝A^TR is A^-1B＝A^TB, then:

the spatial position A can be obtained by installing an attitude sensor on the spray head, and the spatial position B is given by an expected position;

(4) setting the corresponding adjusting angles as gamma, beta and alpha according to the sequence of adjusting around the rotating shaft as z → y → x; the rotation matrix R is then:

wherein R is_z-y-xA space rotation matrix is formed by sequentially rotating around the axes z, y and x by adopting a right-hand coordinate system; rot z, Rot y and Rotx are basic rotation matrixes formed after rotating gamma, beta and alpha around z, y and x axes respectively;

(5) a is to be^TB is associated with the matrix R to solve for γ, β, α, i.e. the nozzle can be adjusted from the spatial position a to the spatial position B by rotating the nozzle in sequence γ around the z-axis, β around the y-axis, and α around the x-axis.

3. The method of claim 1, wherein z is the number of steps of the method₀、z_n、σ(0,z₀)、

And c (0) calibrating the relation between the image pixels and the actual size by using a 50mm fixed-focus lens camera, and calculating and obtaining the image from the shot flow field image.

4. The method of claim 1, wherein h (z) is the control of the fan spray flow field₀) And k was measured using a pitot tube.

5. The method for controlling the fan-shaped spray flow field according to claim 1, wherein the specific process of calculating the distribution of the spray flow field comprises:

(2.1) establishing a plane polar coordinate system to obtain a plane flow intensity function;

randomly intercepting a jet flow section vertical to the axis of the jet flow beam at the jet flow basic section to obtain a plane flow intensity function in any direction in the jet flow section and a function formula of the plane flow intensity function in a plane polar coordinate system; wherein the geometric center of the cross section is O_zxThe distance from the geometric center of the cross section to the nozzle is z_xAnd z is₀≤z_x≤z_n；

Geometric center of cross section O_zxThe angle between any straight line and the positive direction of the x axis, namely the azimuth angle of the straight line is theta (theta belongs to 0 and pi)]) (ii) a On this straight line, the jet flow intensity distribution conforms to the normal distribution law, and the flow intensity function is:

wherein e is Euler number, and the value is about 2.71828; Γ is the magnification of the flow intensity function; mu is the mathematical expectation in probability statistics, with the mathematical meaning of f (mu) ═ f (m)]_max(ii) a Sigma is the variance of the flow intensity, and the value is taken from the distance z from the center of the section to the nozzle_xAnd the azimuth angle theta are related and recorded as

m, theta are parameters, and the following relation exists between coordinate variables x and y in the jet section:

by using the relationship between the parameter variable and the coordinate variable, the flow intensity function is rewritten into a form under a plane polar coordinate system, and then the plane flow intensity function is:

(2.2) correcting the plane flow intensity function after uniqueness test and nonnegativity test;

in a plane polar coordinate system, in order to ensure that the flow intensity value of each point in the jet basic segment has uniqueness and nonnegativity, the plane flow intensity function needs to be corrected as follows:

wherein,

the method is characterized in that a plane flow intensity function is corrected by uniqueness and nonnegativity test of any point on a section under a plane polar coordinate system;

is the geometric center of the cross section

A flow intensity value of (d);

is that

Minimum value in the variable value range of the variable satisfies

(2.3) determining the section boundary of the jet flow by adopting a 3 sigma rule, and perfecting a plane flow intensity function;

in the jet basic section, the flow intensity distribution shape on any jet section can be regarded as an ellipsoid with the jet axis as the center, and any point on the boundary of the ellipse to the geometric center of the section

A distance of

Then

Can be expressed as:

wherein,

each is z ═ z_xWith major and minor semiaxes of the ellipse in the cross-section of the flow injection zone

And is

The planar flow intensity function after the flow boundary definition is:

wherein,

the method is characterized in that a plane flow intensity distribution function in an effective injection area is obtained by examining uniqueness and nonnegativity of any point on a section in a plane polar coordinate system; r is the distance from any point on the section to the geometric center of the section, and the maximum value r_max＝3σ(θ)；

(2.4) in the jet basic section, the elliptical shapes of the effective injection areas of the cross sections at different positions from the nozzle are similar, and the width of the effective injection areas of the cross sections linearly increases along the positive direction of the z axis, namely:

wherein c (theta) is the change rate of the width of the cross-section effective injection area along the z-axis and is related to the azimuth angle theta;

is z ═ z₀Variance of flow intensity distribution on straight lines at different angles from the positive direction of the x-axis in cross section, and σ (θ, z)₀) Have the same meaning, i.e. have

σ_z(θ)＝σ(θ,z)；

Extracting z ═ z₀In the cross section, the variance σ (0, z) of the flow intensity distribution in the major and minor semiaxes of the ellipse of the effective flow ejection region₀)、

And when the azimuth angle theta is 0 degrees, the slope c (0) of the flow field outer contour along the positive direction of the z axis is obtained, and the change rate c (theta) of the effective flow injection area on any azimuth angle theta is obtained:

wherein c (0), σ (0, z)₀)、

All related to the structure of the nozzle, the gas-liquid pressure and the ratio of the gas-liquid pressure at the inlet of the nozzle, the viscosity of the liquid, the density of the liquid and the surface tension of the liquid;

(2.5) obtaining a flow intensity function on the central axis of the jet flow according to the attenuation rule of the central flow intensity of the jet flow along the z axis, and further obtaining a spatial flow intensity distribution function; the jet center flow intensity decreases in a hyperbolic curve along the z-axis, namely:

wherein, the larger the k value is, the slower the decay speed of the flux intensity of the central axis of the jet along the z axis is; the smaller the k value is, the faster the decay speed of the flux intensity of the central axis of the jet along the z axis is;

Q_z(0, theta) represents the intensity function of the flow at the azimuth angle theta on a section perpendicular to the z-axis and passing through the central axis of the jet, written in the form of Q (0, theta, z), abbreviated as h_zOr h (z), i.e. Q_z(0,θ)＝Q(0,θ,z)＝h_zH (z); then passing through the central axis of the jet, where z is z₀On a cross section, the flow intensity function at the azimuth angle theta is

Namely, the method comprises the following steps:

in combination with (2.3)

The spatial flux intensity distribution function is:

6. the method as claimed in claim 1, wherein the reduction of the gas-liquid pressure and flow rate at the nozzle inlet is defined as Q_c-Q_t≥1×10^-3When the jet flow basic section is adopted, the gas-liquid pressure and the flow of the nozzle inlet are reduced at the same time, and then the flow intensity set Q at the central position of each small square body of the effective flow injection area in the jet flow basic section is obtained_cDecrease; the increase of the gas-liquid pressure and the flow rate at the inlet of the nozzle refers to Q_c-Q_t<1×10^-3When the gas-liquid pressure and the flow of the nozzle inlet are simultaneously increased, the flow intensity set Q at the central position of each small cube of the effective flow injection area in the basic jet flow section is obtained_cAnd is increased.

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