RU2192564C2 - Turbomachine overrotor device - Google Patents

Abstract

FIELD: axial flow turbomachines. SUBSTANCE: invention relates to overrotor devices with recirculating flow of medium in stages of axial flow turbomachines. Proposed device has ring duct wall with space outside duct and rotor blades rim. Radial clearance is formed between peripheral end faces of blades and duct wall. Duct wall is provided with rows of holes communicating duct with space outside duct, holes being located above and below leading edges of rotor blades in direction of flow. Holes in duct wall located above leading edges of rotor blades in direction of flow are made in form of rows of slots orientated circumferentially in direction of rotation of rotor blades. Holes in duct wall located below leading edges or rotor blades are made in form of slots orientated in direction of flow in inter-blade channels of rotor blades. Edges of each row of slots of duct wall orientated circumferentially are arranged in space of duct below in direction of flow than edges of each corresponding row of slots orientated circumferentially in space outside duct and at a smaller radial distance from axis of rotation of rotor blade rim than distance from axis of rotation to peripheral end faces of rotor blades. In duct wall of each slot orientated in direction of flow in inter-blade channels of rotor blades, edges in space of duct in circumferential direction as to rotation of rotor blades are located higher in flow than edges of each corresponding slot in space outside duct. EFFECT: enlarged range of stable operation, increased efficiency, reduced compressor noise level. 4 dwg

Description

 The invention relates to nadrotorny devices with a recirculating fluid flow in the stages of axial turbomachines, mainly for power plants and gas pumping stations.

 Known stage axial compressor containing guides and rotor blades, sequentially placed with an axial clearance in the housing having an annular closed cavity bounded on the side of the duct part of the stage by a stator ring with slots located obliquely to the radius of the housing in the direction of rotation of the rotor blades and communicating the annular cavity with flow part. Each slot has the shape of an arc with rounded edges, and in the plane perpendicular to the radius of the stator ring, the angles formed by the longitudinal axis of the axial compressor stage and tangent to the midline of the gap at the points of intersection of the line with the diametrical sections of the ring at opposite ends of the gap are respectively equal to the angles of the blades previous guide vane and rotor blades [1].

 A disadvantage of the known design is the incomplete use of the possibilities of increasing efficiency and expanding the range of stable operation while reducing the loss of full pressure and maintaining air flow. The use of a known design for the first rotary stages of an axial turbomachine, i.e., without previous guide vanes, increases pressure losses in the interscapular channels of the rotor stage and in the cavity outside the tract. This is explained by the mismatch of the configuration of the slots to the trajectories of the air flow and to the lines of equal static pressure, increased turbulization of the air flow, an increase in the resistance of the recirculating flows in the off-track cavity and the flow flows in the interscapular channels.

 The bypass part of the casing of an axial gas turbine engine is known, which provides improved operation of compressor rotor blades, comprising an annular path wall with a cavity outside the path and a rotor blade rim, with a radial clearance between the upper end parts of the rotor blades and the path wall and rows of holes are made in the path wall, communicating the flow path with a cavity outside the path and located upstream and downstream of the inlet edges of the rotor blades [2].

 A disadvantage of the known design is that the inner surface of the path wall, the cavity outside the path, and the plates in the cavity outside the path form a cross-sectional section, which reduces the drop in the recirculating flow, increases pressure losses due to increased turbulization of the flow and increased resistance in the off-line cavity. The design drawback is also the incomplete use of the possibilities of reducing the noise level and adjusting the tonality (spectrum) of noise from the first compressor rotor stage downstream.

 A device is known for actively transferring fluid through a casing channel near fan blades. In a known construction, a channel provided with stator blades is made in a fixed casing. Under certain operating conditions of the engine or aircraft, the flow recirculating in the channel is controlled or blocked. In another embodiment, to reduce or prevent shear waves created by the rotor blades, a device (aneroid valve) is used that controls the flow in the extra-cavity cavity [3].

 A disadvantage of the known design is the high cost and complexity of manufacturing a casing with stator blades in its walls, as well as a decrease in the pressure drop of the recirculating flow due to the shorter distance between the inlet and outlet of the channels above the periphery of the end part of the blade. This increases the pressure loss, requires a higher level of noise isolation of the inlet tract, especially for ground turbomachines.

 Closest to the claimed is the design of the rotor device of the turbomachine, containing an annular path wall with a cavity outside the path and a rotor blade wreath, between the peripheral ends of the blades of which and the path wall there is a radial clearance, and in the path wall there are rows of holes communicating the flow path with the cavity outside the path and located upstream and downstream of the inlet edges of the rotor blades. The path wall is made of perforated holes of small diameter and a thickness proportional to the diameter of the hole, and the axis of the holes is directed inside the gas-air duct towards the front edges of the blade crown at a calculated angle to the generatrix of the path wall in the diametrical plane and in the circumferential direction [4].

 A disadvantage of the known design is a narrow range of stable operation, lower efficiency of the compressor stage and an increased noise level when it is used as the first diagonal stage of the low pressure compressor without input guide vanes mainly for ground turbomachines. The presence of perforated rows of holes in the path wall located upstream and downstream from the inlet edges of the rotor blades provides increased resistance to the recirculating fluid flow into the off-line cavity, which leads to increased turbulence of the rotating vortices over the ends of the rotor blades, reducing air flow through the compressor and contributing to I'll make it up A disadvantage of the known design is also the high pressure loss in the interscapular channels of the rotor blades due to the short communication time of the tract with an extra-path cavity with perforated holes, as well as the difficulty of expanding the range of stable operation and reducing noise.

 The technical problem to be solved by the claimed invention is aimed at expanding the range of stable operation, increasing efficiency and decreasing the compressor noise level of the axial turbomachine by reducing the pressure loss of the recirculating fluid flow and the formation of a resonator cavity outside the path that absorbs sound vibrations arising when rotating the rotor stage.

 The essence of the technical solution lies in the fact that in the rotor device of the turbomachine containing an annular tract wall with a cavity outside the tract and a rotor blade wreath, there is a radial clearance between the peripheral ends of the blades of the blades and the path wall, and rows of holes are made in the tract wall that communicate with the flow path cavity outside the path and located upstream and downstream from the input edges of the rotor blades, according to the invention, openings in the path wall located upstream of the input edges p otor blades are made in the form of rows of slots oriented in the circumferential direction along the rotation of the rotor blades, and the holes in the path wall located downstream of the inlet edges of the rotor blades are made in the form of slots oriented downstream in the interscapular channels of the rotor blades, the edges of each row of slits of the path wall, oriented in the circumferential direction, are located in the cavity of the path downstream than the edges of each of the corresponding rows of slits, oriented in the circumferential direction in the cavity in not the path, and at a smaller radial distance from the axis of rotation of the rotor blade of the rim than the distance from the axis of rotation to the peripheral ends of the rotor blades, and in the path wall, in each slot, oriented along the flow in the interscapular channels of the rotor blades, the edges in the cavity of the tract, the circumferential direction of rotation of the rotor blades are located upstream than the edges of each corresponding gap in the cavity outside the path.

 The holes in the path wall located upstream of the input edges of the rotor blades, in the form of rows of slots oriented in the circumferential direction along the rotation of the rotor blades, reduce the instantaneous values of pressure pulsations and pulse amplitudes of the recirculated fluid flow injected into the tract in front of the input edges of the rotor blades shoulder blades. This reduces pressure losses, eliminates pressure unevenness at the inlet to the rotor stage, expands the range of stable operation of dynamic compressors (low and high pressures), and also reduces the noise level from the rotor stage.

 The holes in the path wall located downstream of the input edges of the rotor blades in the form of slots oriented downstream in the interscapular channels of the rotor blades, i.e. at angles equal to the instantaneous absolute speed in each interscapular channel, it allows selection of rotating vortices along lines of equal levels of static pressure in the interscapular channels above the peripheral part of the rotor stage. This reduces the resistance to the recirculating fluid flow at the entrance to the extra-cavity, reduces the turbulization of the rotating vortices above the peripheral ends of the rotor blades, and reduces the pressure loss in the interscapular channels of the rotor blades. In addition, this embodiment of the slots increases the communication time through the slots of the path and extra-path cavities, which are periodically closed and opened by the rotor blades, and allows you to synchronize the wave movement of compressed air in the cross section of the tract from the zones of the interscapular channels located downstream of the input edges of the rotor blades, through the cavity outside the tract and further to the entrance of the rotor stage.

 The execution of the edges of each row of slits of the path wall, oriented in the circumferential direction along the rotation of the rotor blades, in the cavity of the tract is lower in flow than the edges of each of the corresponding rows of slits oriented in the circumferential direction in the cavity outside the path, as well as at a smaller radial distance from the axis of rotation rotor blade rim than the distance from the axis of rotation to the peripheral ends of the rotor blades, provides a continuous flow of air flow along the path wall in front of the peripheral part of the input edges rotor blades. This reduces pressure losses due to the synchronization of the wave movement of compressed air by the rotor blades in the cross section of the tract with respect to the wave velocity, which depends on the frequency of the rotating stall above the first stage of the rotor blades. In addition, pressure losses are reduced by increasing the pressure drop of the air stream recirculating in the off-line cavity. The pressure differential increases due to the diffuser circuit formed by the path wall, which further reduces the noise level from the first stage of the rotor blades stream.

 The execution in the path wall of the edges of each gap, oriented downstream in the interscapular channels of the rotor blades, located upstream than the edges of each corresponding gap in the cavity outside the path, reduces the resistance when air flows with rotating vortices above the rotor blades through the cracks.

 Figure 1 shows the rotor device of the turbomachine.

 Figure 2 - element I in figure 1.

 Figure 3 is a view A in figure 2.

 Figure 4 is a section bB in figure 3.

 The turbomachine’s rotor device contains an annular path wall 1 with a cavity outside the path 2 and a rotor blade rim 3, between the peripheral ends 4 of the blades 5 of which and the path wall 1 there is a radial clearance d. In the path wall 1, rows of holes 6 and 7 are made (see FIG. 3), communicating the flow path 8 with a cavity outside the path 2 and located upstream and downstream 9 from the inlet edges 10 of the rotor blades 5 (see FIG. 2). The cavity outside the path 2 is formed by the housing 11 of the low-pressure compressor and the annular path wall 1. The holes 6 in the path wall 1, located upstream 9 from the input edges 10 of the rotor blades 5, are made in the form of rows of slots 12, 13, 14, 15, oriented in the circumferential direction 16 along the rotation of the rotor blades 5. The holes 7 in the path wall 1, located downstream of 9 from the input edges 10 of the rotor blades 5, are made in the form of slots 17 oriented along the stream 18 in the interscapular channels of the rotor blades 5. Edges 19 of each rows 12, 13, 14 silt and 15 slots of the path wall 1, oriented in the circumferential direction 16, are placed in the cavity of the path 8 downstream 9 than the edges 20 of each of the respective rows 12, 13, 14 or 15 of the slots oriented in the circumferential direction 16 in the cavity outside of the path 2, and at a smaller radial distance r from the axis of rotation 21 of the rotor blade 3, than the distance R from the axis of rotation 21 to the peripheral ends 4 of the rotor blades 5 (see figure 2, 3). In the path wall 1, in each slit 17, oriented in the flow 18 in the interscapular channels of the rotor blades 5, the edges 22 in the cavity of the tract 8 in the circumferential direction 16 are located upstream of the rotor blades 5 (the circumferential component of the stream 16) than the edges 24 of each corresponding slit 17 in the cavity outside the tract 2 (see Fig. 4). In addition, pos. 25 - the direction of air flow at the entrance to the cavity outside the path 2, and pos. 26 - direction of air flow from the cavity outside the path 2 to the input of the rotor blades 5.

 The device operates as follows. Pressure pulsations in the flow path 8 downstream of 9 from the rotor blades 5 take the form of complex vibrations, the frequency spectrum of which consists of a solid part and individual components in the form of a blade frequency modulated by the frequency of a rotating stall. A rotating vortex above the peripheral edges 4 of the rotor blades 5 is taken in the direction of pos. 25 due to the pressure drop through a series of slots 17 oriented along the flow 18 in the interscapular channels between the blades 5 of the rotor stage 3, i.e. in absolute motion. The inclined slots 17 due to the sharp edges 22 on one of the sides reduce the resistance of the rotating vortices above the ends 4 of the rotor blades, reduce the turbulization of the air flow and increase the throughput of the slots. In the off-field cavity 2, damping of the rotating vortices takes place and the recirculated air stream is darted along the arrow 26 into the air stream 9 in front of the inlet edges 10 of the rotor blades 5. The cavity outside the path 2 is a Helmholtz chamber resonantly tuned to the frequency of the rotating stall above the peripheral ends 4 of the rotor blades 5 using a certain ratio of the passage areas and the number of rows of 12, 13, 14 and 15 slots oriented in the circumferential direction 16 along the rotation of the rotor blades 5, and slots 17 oriented along the flow 18 in m to the root canal of the rotor blades 5, and also due to the diffuser nature of the annular path wall 1. In this case, “locking”, i.e. there is no reduction in air flow preceding the surge, pressure losses of the recirculated flow do not exceed the losses without stalling over the ends 4 of the rotor blades 5, the efficiency increases and the noise level of the rotor stage of the axial turbomachine decreases.

Sources of information
1. Patent RU 2066402, MKI F 04 D 19/00, 1993

 2. Patent US 5474417, MKI F 01 D 1/12, 1994

 3. Patent WO 9510692, MKI F 01 D 11/08, 1995

 4. Application RU 98108515/06, MKI F 04 D 29/66, 1998 - prototype.

Claims (1)

 A turbomachine nadrotor device containing an annular tract wall with a cavity outside the tract and a rotor blade rim, between the peripheral ends of the blades of which and the tract wall there is a radial clearance, and rows of holes are made in the tract wall that communicate with the cavity duct outside the tract and located above and below flow from the inlet edges of the rotor blades, characterized in that the holes in the path wall located upstream of the inlet edges of the rotor blades are made in the form of rows of slots, a guide The holes in the circumferential direction of rotation of the rotor blades, and the holes in the path wall located downstream of the inlet edges of the rotor blades, are made in the form of slots oriented in the flow in the interscapular channels of the rotor blades, while the edges of each row of slots of the path wall are oriented in circumferential direction, placed in the cavity of the tract downstream than the edges of each of the corresponding rows of slots, oriented in the circumferential direction in the cavity outside the path, and at a smaller radial distance from the axis rotation of the rotor blade rim than the distance from the axis of rotation to the peripheral ends of the rotor blades, and in the path wall in each slot, flow oriented in the interscapular channels of the rotor blades, the edges in the cavity in the circumferential direction along the rotation of the rotor blades are located upstream than the edges each corresponding gap in the cavity outside the tract.

Images