CN105179322A - Gas compressor stationary blade cascade with equal-width linear groove formed in blade root - Google Patents

Abstract

The invention provides a gas compressor stationary blade cascade with an equal-width linear groove formed in a blade root and relates to the passive flow control technology in the technical field of turbomachinery. By means of the gas compressor stationary blade cascade, the equal-width linear groove is formed in the blade root end wall of the gas compressor stationary blade cascade from the pressure face to suction face, and jet flow is formed through detour flow pressure differentials of a blade, so that flow separation is restrained and delayed. The groove is located in the blade root end wall of the gas compressor stationary blade cascade. The spanwise height is a constant value. The inlet of the groove is located in the pressure face of the stationary blade cascade. The outlet of the groove is located in the suction face of the blade cascade. The center line of the groove is a straight line and equidistant from the two side walls of the groove. The gas compressor stationary blade cascade has the beneficial effects that corner separation is restrained; the flow capacity of the blade cascade is increased; the total pressure loss is reduced; the diffusion capacity is improved.

Description

Compressor stator cascade with equal-width linear grooves at the blade root

technical field

The invention relates to the flow control of a stator cascade of a compressor, in particular to a flow control scheme for slotting a blade root of a stator cascade of a compressor to suppress the angular separation of the compressor stator, and belongs to the passive flow control technology in the technical field of impeller machinery.

Background technique

Among the internal flow of turbomachinery, the most complicated flow is the flow in the corner region. The end wall boundary layer, blade boundary layer, various vortex structures and their interactions exist in the corner flow between the suction surface and the end wall, which are the main factors that cause the performance deterioration of the compressor stator. The flow separation in the corner area will lead to channel blockage, blade load and diffuser capacity reduction, resulting in total pressure loss and efficiency reduction, and in severe cases, it will cause engine surge. The flow loss in the corner area of the compressor stator accounts for a large proportion of the total loss of the stage. Therefore, trying to suppress the corner separation of the compressor stator is an important way to reduce the corner loss and delay the engine performance deterioration caused by the corner separation.

At present, the flow control technologies for compressor stator corner separation and stall can be mainly divided into two categories: active control and passive control. Active control technologies mainly include plasma excitation, boundary layer blowing technology, synthetic jet, etc.; passive control technologies mainly include vortex generators, wing knives, end wall molding, etc. These control methods have both advantages and disadvantages, and the corner area control method needs further research.

Our research group previously proposed the technology of slotting the blade root to control the separation of the corner area of the cascade (Gas Turbine Test and Research, 2007, Vol.20, No.3, 28-33). , using the pressure difference between the pressure surface and the suction surface of the blade to form a jet, increase the kinetic energy of the low-energy fluid in the corner area, and blow off the air flow on the suction surface of the blade and the boundary layer of the end wall, thereby inhibiting the separation of the corner area. The specific implementation method is as follows: first, points A, B, C, and D are respectively taken at different positions on the pressure surface and the suction surface of the blade, and then the arcs are used to connect AC and BD to form a channel. The above-mentioned technology has at least the following disadvantages: For engineering applications, the connecting arcs of the slotting scheme are relatively random, which is not easy to process; there are too many control parameters, and the lack of design criteria makes it difficult to optimize the design of the control scheme.

Contents of the invention

The purpose of the present invention is to propose a blade root slotting control method that is easy to process and convenient to optimize the design of geometric parameters to control the separation flow in the corner area of the stator blade cascade of the compressor.

Technical scheme of the present invention is as follows:

Open a channel at the end wall of the blade root of the stator blade cascade of the axial flow compressor;

Wherein, the spanwise height of the slot is a constant value, and takes a value between 2% and 20% of the height of the cascade.

There can be one or more channels;

The inlet of the channel is located on the pressure surface of the stator blade cascade of the compressor;

The outlet of the channel is located on the suction surface of the stator blade cascade of the compressor;

The axial position where the channel inlet is located is located upstream of the axial position where the channel outlet is located;

The joints between the channels and the blades have rounded transitions;

The center line of the channel is a straight line, and the two side walls of the channel are equidistant from the center line.

It should be noted that, for the open equal-width linear slots proposed in this paper, based on the analysis of the control front cascade flow field, a better control scheme is quickly given. The specific design criteria corresponding to this control method are as follows: According to the flow field analysis of the original cascade calculation results, the jet velocity V and the jet flow rate m are first determined, and based on the jet velocity V, the pressure difference Δp between the required pressure surface and suction surface is back-calculated =P1-P2 (low-speed cascade, generally Mach number is less than 0.3) or pressure ratio Pt=P1/P2 (high-speed cascade, generally Mach number is less than 0.3), so as to determine the groove position on the pressure surface (corresponding to pressure P1) and the suction surface The slotting position (corresponding to the pressure P2), and then the slotting width is obtained according to the flow rate m and the jet velocity V. In this way, the preliminary control scheme can be obtained very quickly, and it is very convenient to carry out the optimal design of slotting on this basis.

The beneficial effect of the present invention is that: by opening equal-width linear grooves from the pressure surface to the suction surface at the root end wall of the stator blade cascade of the compressor, the pressure difference between the pressure surface and the suction surface of the blade itself is used to form a high-speed jet. The high-speed jet increases the kinetic energy of the low-energy fluid in the corner area, making it more capable of resisting the reverse pressure gradient, and avoiding the premature separation of the flow in the corner area; The laminar airflow becomes thinner and faster, the boundary layer velocity pattern is fuller, the ability to resist the reverse pressure gradient is stronger, and the flow separation between the suction surface and the end wall is suppressed. Inhibit the separation of the corner area, thereby increasing the flow capacity of the cascade, reducing the total pressure loss, and increasing the diffusion capacity.

Compared with the control technology proposed by our research group in the early stage, the equal-width linear groove has the advantage of being easy to process; and the corresponding design criteria are given, which can quickly carry out the preliminary design of the control scheme, and it is very convenient to carry out optimized design, which has good engineering Application prospect.

Description of drawings

Fig. 1 is a schematic diagram of the structure of a stator blade cascade of a compressor with linear grooves of equal width on the blade root.

Fig. 2 is a cross-sectional schematic diagram of a compressor stator cascade channel with equal-width linear slots in the blade root.

Fig. 3 is a schematic diagram of a stator blade cascade of a compressor with linear grooves of equal width on the blade root along the spanwise direction of the cascade.

Fig. 4 is a streamline diagram of the cascade surface and end wall of the prototype cascade without slots in the blade root.

Fig. 5 is a streamline diagram of the surface and end wall of the compressor stator cascade with straight grooves of equal width on the blade root.

Figure 6 is a comparison of the performance parameters of the compressor stator cascade with equal-width linear grooves in the blade root and the prototype cascade without grooves in the blade root.

Detailed ways

Specific embodiments of the present invention will be described below in conjunction with the accompanying drawings.

As shown in Figure 1, for a compressor stator cascade with equal-width linear grooves at the blade root, an equal-width linear groove 5 is provided at the end wall 2 of the root of the cascade 1 from the pressure surface 3 to the suction surface 4 of the cascade 1 .

As shown in Figure 2, according to the PVD prototype stator cascade flow field, the position of the outlet of the channel 5 on the suction surface 4 is selected before the separation point; along the axial direction of the cascade, the position of the inlet of the channel 5 on the pressure surface 3 Located upstream of the outlet of the suction surface 4; according to the pressure distribution on the surface of the PVD prototype stator cascade, the position of the inlet of the channel 5 on the pressure surface 3 is selected at the place where the static pressure on the upper surface of the pressure surface 3 is relatively large; the distance between the two side walls of the channel 5 and the center The distance between the lines is 4% of the axial chord length, and this value can be adjusted between 0.5% and 6% according to the actual situation.

As shown in Fig. 3, the channel 5 has the same height in the span direction, which is 10% of the span height, and this value can be adjusted between 2% and 20% of the span height according to the actual situation.

In order to verify the effect of the present invention, the inventors performed numerical simulations on the PVD prototype cascade without linear grooves in the blade root and the compressor stator cascade with equal-width linear grooves in the blade root. The specific simulation parameters and results are as follows:

The PVD cascade airfoil parameters used for simulation are shown in the table below:

As shown in Figure 4 and Figure 5, by comparing the streamline diagrams of the suction surface 4 and the end wall 2 before and after slotting, it can be found that the compressor stator cascade with equal-width linear grooves in the blade root and the PVD without grooves in the blade root Compared with the prototype cascade, the separation flow area formed by the suction surface and end wall surface of the cascade after slotting is significantly reduced, so the equal-width linear grooves in the blade root can delay and inhibit the occurrence of separation.

As shown in Fig. 6, through the results of the total pressure loss coefficient, lagging angle and pressure ratio of the numerical simulation, it can be seen that the compressor stator cascade with slotted root slots of equal width and linear shape is comparable to the prototype cascade. Ratio, the total pressure loss coefficient is reduced by 18.07%, the lagging angle is reduced by 38.74%, and the pressure ratio is increased by 0.033%.

It can be seen that the design of the self-pressure differential jet compressor stator cascade with equal-width linear grooves in the blade root of the present invention improves the suction surface of the cascade and the flow conditions of the end wall boundary layer through the slotted jet flow, and reduces the pressure of the end wall. The area of the separation area realizes the purpose of suppressing the separation of the corner area. In turn, the loss caused by the separation of the corner area is reduced, the total pressure loss and lagging angle are reduced, and the pressure ratio is increased, which is beneficial to improving the performance and stability of the compressor.

Claims (1)

1. an axial-flow compressor stator leaf grating, is characterized in that:

Conduit (5) is offered at blade root end wall (2) place of axial-flow compressor stator leaf grating (1),

Wherein, the exhibition of described conduit to being highly steady state value, and get leaf grating height 2% to 20% between value,

Described conduit (5) can have one or more,

Described conduit (5) import is positioned at Profile For Compressor Stator leaf grating (1) pressure side (3),

Described conduit (5) outlet is positioned at Profile For Compressor Stator leaf grating (1) suction surface (4),

Described conduit (5) import place axial position is positioned at conduit (5) outlet axial position upstream, place,

Described conduit (5) and Profile For Compressor Stator leaf grating (1) connection all round-corner transitions, described conduit (5) center line is straight line, and conduit (5) two side and center line equidistant.