CN115788600A - Stator blade with self-air-entraining front edge and self-adaptive air-jet blade top - Google Patents

Abstract

The invention relates to a stator blade with a self-air-entraining front edge and self-adaptive air injection at a blade top, belonging to the field of impellers; the stator blade is internally provided with a flow passage, the flow passage comprises a blade front edge air inlet hole, a blade top air injection hole and an internal cavity, incoming flow air sucked from the blade front edge air inlet hole flows to the blade top air injection hole through the blade internal cavity, and is sprayed to a stator blade tip gap from the blade top air injection hole. The invention forms a flow channel by the air inlet hole at the front edge of the blade, the internal cavity and the air jet hole at the top of the blade to form a static blade structure for self-bleed air and self-adaptive air jet at the top of the blade, and can realize the passive control of inhibiting the leakage flow of the blade tip. Compared with the traditional air injection technology, the invention does not need additional external air injection equipment, has the characteristic of self air induction, and has the technical advantages of simple structure and light weight; compared with blades with tip shapes such as shrouded blades and the like, the mass of an end area is not required to be increased; the blade tip air injection can effectively inhibit the blade tip leakage flow and reduce the blade tip leakage flow.

Description

Stator blade with self-air-entraining front edge and self-adaptive air-jet blade top

Technical Field

The invention belongs to the field of impellers, and particularly relates to a stator blade with a front edge capable of self-entraining air and a blade top capable of self-adaptive air injection, which is suitable for an aircraft engine.

Background

The blade tip clearance in the impeller machinery is introduced for avoiding the friction collision of the blade and the casing or the hub wall surface, and under the action of the pressure difference between the two sides of the pressure surface and the suction surface of the blade tip element, part of fluid turns over the blade tip clearance to form blade tip leakage flow, and under the synthetic action of the main flow speed, the leakage flow usually exists in a blade tip area in the form of leakage vortex, and is complex three-dimensional viscous flow. For an aircraft engine, the influence caused by tip leakage flow is mainly reflected in the generation of leakage loss and blockage, and for a compressor, the tip leakage flow can reduce the efficiency, the pressure-rise capacity and the stable working range of the compressor; for the turbine, tip leakage flow mainly affects the reduction of turbine efficiency, and high temperature leakage flow subjects the tip to extremely high thermal loads. And as the size of the blade tip clearance is increased, the strength of the blade tip leakage flow is enhanced, and the caused negative effect is also enhanced. The tip clearance cannot be completely eliminated, and the minimum size of the tip clearance is limited by factors such as the size of a blade, the rotating speed and materials, so that the performance and the benefit of the aeroengine are influenced for a long time due to negative effects caused by tip leakage flow. With the development of high thrust-weight ratio and high performance of the aircraft engine, the control of blade tip clearance loss and blade tip leakage flow becomes more and more important.

In order to solve the problems, a great deal of research and research is carried out at home and abroad, and the current methods for controlling the blade tip leakage flow and the loss thereof mainly comprise: traditional case processing, blade tip case jet, active blade top suction, shrouded blade and labyrinth seal, rib blade and blade tip winglet. The traditional casing treatment mainly means that special structures (such as grooves and seams) are arranged on the casing to reduce channel blockage caused by tip leakage flow, an annular wall boundary layer and the like and improve tip flow distribution, so that the stall margin of the compressor is improved, but the efficiency of the compressor is reduced while the stall margin of the compressor is improved by the traditional casing treatment; the blade tip case jet has two forms of active control and passive control, the control principle is that the blade tip load is reduced, the blade tip leakage vortex or the unsteady effect is inhibited through jet, the stability expanding effect is achieved, and the action rule and mechanism of the blade tip case jet are still explored; the air injection at the top of the driving blade forms a blocking area through the clearance of the blade tip, so that the strength of leakage flow flowing from the pressure side to the suction side is weakened; the suction of the active blade top directly reduces the actual flow of leakage flow to achieve the effect of controlling leakage. And the jet of the driving blade top and the suction of the driving blade top both need to be provided with additional devices, and have the defects of complicated structure and reduced reliability of the engine. The shrouded blades, the rib blades and the blade tip winglets are mostly applied to turbine blades, the flow field of a blade tip region is controlled by changing the blade tip structure, leakage flow and leakage loss can be effectively reduced, the loss of the end region is still large, the cooling of the end region is difficult, the quality of the end part of each blade is improved, the stress of each blade is increased, and adverse effects are generated on the creep performance, the aerodynamic response and the service life of each blade.

In view of the above, the invention provides a stator blade structure for inhibiting tip leakage flow, which is suitable for a compressor and a turbine and realizes passive control of the tip leakage flow of the stator blade.

Disclosure of Invention

The technical problem to be solved is as follows:

in order to avoid the defects of the prior art, the invention provides the stator blade with the front edge capable of self-entraining air and the blade tip capable of self-adaptive air injection, so that the defects that an additional structure is needed for active control and the detection and execution difficulty of a flow field of an active control mechanism are avoided, the problem that the end area is heavy due to the molding of the shrouded blade and the blade tip is avoided, the passive control on the blade tip leakage flow is realized on the stator blade, and the effect of inhibiting the blade tip leakage flow is achieved. The invention arranges the communicating flow channel between the front edge of the stator blade and the blade top, and leads the air from the front edge of the blade to generate jet flow at the blade top, and the jet flow plays a sealing role at the blade tip clearance, thereby inhibiting the blade tip leakage flow and achieving the effect of reducing the blade tip leakage flow.

The technical scheme of the invention is as follows: the stator blade comprises a blade front edge air inlet hole, a blade top air jet hole and an internal cavity, wherein incoming airflow sucked from the blade front edge air inlet hole flows to the blade top air jet hole through the internal cavity of the blade, and is jetted to a stator blade tip gap from the blade top air jet hole.

The further technical scheme of the invention is as follows: the blade top air injection holes are arranged near the initial region of the blade tip leakage vortex or near the region with the maximum blade tip leakage strength.

The further technical scheme of the invention is as follows: the blade top gas injection holes are distributed along the blade profile mean camber line, and the number of the blade top gas injection holes is 1-3.

The further technical scheme of the invention is as follows: the aperture of the blade top air injection hole accounts for 20% -40% of the thickness of the blade top.

The invention further adopts the technical scheme that: the jet angle of the blade top jet hole is opposite to the direction of leakage flow in the circumferential direction.

The further technical scheme of the invention is as follows: the structure of the blade top air injection hole adopts a contraction nozzle.

The invention further adopts the technical scheme that: the air inlet holes of the front edge of the blade are distributed on the front stagnation point under the design working condition of the front edge of the blade.

The further technical scheme of the invention is as follows: the air inlet holes at the front edge of the blade are distributed at the positions with 60-90% of the blade height, the number of the air inlet holes is 1-3, and the air inlet holes are distributed at equal intervals.

The further technical scheme of the invention is as follows: the aperture of the air inlet hole at the front edge of the blade accounts for 20-50% of the small diameter of the front edge of the blade.

The further technical scheme of the invention is as follows: the air inlet hole at the front edge of the blade is of an expansion structure facing the incoming flow direction, and the expansion angle is 0-5 degrees.

The working principle is as follows: the invention uses the air inlet hole at the front edge of the blade, the inner cavity and the air jet hole at the top of the blade to form a self-bleed air and self-adaptive air jet structure of the stationary blade. For an axial flow compressor, the axial flow compressor is mainly pressurized along the axial direction, the airflow at the front section of the blade tip of the axial flow compressor is not fully pressurized, and the stagnation pressure of the incoming flow gas at the front edge of the blade is greater than the static pressure at the gap of the blade tip; for the turbine, airflow flows along the same pressure, the stagnation pressure of the incoming airflow at the blade front edge is also larger than the static pressure at the blade tip clearance, and the pressure difference formed by the stagnation pressure of the airflow at the blade front edge and the static pressure at the blade tip clearance can provide driving force for the self-bleed air and the self-adaptive flow path. When the stator blade is formed by a flow structure for communicating the front edge of the blade with the blade top, incoming flow airflow flows in from the air inlet hole of the front edge of the blade, speed reduction and pressurization are realized in the flow of the internal cavity of the blade, and pressure higher than static pressure at the blade tip gap is obtained, namely, the driving force for ejecting the internal cavity airflow from the jet hole at the blade top is obtained, so that the airflow can flow through the internal cavity of the blade, and finally the airflow is ejected from the jet hole at the blade top, and the sealing effect is realized at the blade tip gap, thereby inhibiting the tip leakage flow and reducing the tip leakage flow.

The control effect of the invention on the tip leakage flow changes along with the change of the incoming flow speed, the incoming flow speed is increased, the larger the momentum of the introduced air flow is, the energy of the gas ejected from the blade top is increased, namely the sealing effect of the blade top air jet at the blade tip clearance is enhanced. Therefore, the invention has self-adaptability to the control effect of the tip leakage flow.

Advantageous effects

The invention has the beneficial effects that: the invention forms a flow channel by the air inlet hole at the front edge of the blade, the internal cavity and the air jet hole at the top of the blade to form a static blade structure for self-bleed air and self-adaptive air jet at the top of the blade, and can realize the passive control of inhibiting the leakage flow of the blade tip. Compared with the traditional air injection technology, the invention does not need additional external air injection equipment, has the characteristic of self air induction, and has the technical advantages of simple structure and light weight; compared with blades with tip shapes such as shrouded blades and the like, the mass of an end area is not required to be increased; the blade tip air injection can effectively inhibit the blade tip leakage flow and reduce the blade tip leakage flow rate. The effect of the invention on inhibiting the tip leakage flow changes with the change of the incoming flow speed, the incoming flow speed increases, the larger the momentum of the introduced air flow is, the energy of the gas ejected from the blade top can be increased, namely the sealing effect of the blade top air jet at the blade tip clearance is enhanced, so the invention has self-adaptability on the control effect of the tip leakage flow.

The position distribution of the blade top air injection holes can influence the inhibition effect of blade tip leakage flow. The jet holes are arranged near the initial area of the tip leakage vortex, so that the strength of the tip leakage vortex is expected to be weakened, or the initial position of the tip leakage vortex is moved backwards, and the effect of improving the flow field is achieved by shortening the effective mixing distance between the tip leakage vortex and the main flow; the air holes are arranged in the area with high tip leakage flow strength, so that the tip leakage flow strength is expected to be better weakened, and the tip leakage flow rate is reduced. The research shows that the initial position of the tip leakage vortex can gradually move forward along with the increase of the attack angle of the incoming flow or the thickening of the inlet boundary layer, so that the distribution position of the blade top jet hole needs to consider the conditions of the tip leakage flow under different working conditions and the corresponding control effect, and the effect that the blade top jet can well inhibit the blade tip leakage under different working conditions is achieved. The CFD technology is used for researching the tip leakage flow of the stator blade, so that the distribution conditions of the tip leakage flow and the tip leakage vortex can be judged in advance, the position distribution of the top jet holes can be reasonably arranged, the CFD technology is further used for researching the control effect of the control method, and the optimal position distribution of the top jet holes is expected to be determined after repeated iteration.

The change of the blade top air injection direction can influence the control effect on the blade tip leakage flow, when the air injection direction is opposite to the blade tip leakage flow direction, the air injection control effect is good, the sealing effect can be effectively achieved, and the blade tip leakage flow is restrained.

The blade tip jet speed influences the control effect of the blade tip leakage flow, and the blade tip leakage flow can be better inhibited by the jet speed as large as possible. The jet speed of the blade top is influenced by a plurality of factors, and the jet speed of the blade top can be influenced by the pressure difference between the air inlet hole pressure of the front edge of the blade and the jet hole pressure of the blade top and the aerodynamic loss of a flow passage of a cavity in the blade. The nozzle structure for blade top air injection adopts a contraction nozzle, so that the air injection speed can be increased, the air flow momentum can be increased, and the effect of better inhibiting blade tip leakage flow can be achieved by using smaller air injection quantity.

The size of the air injection quantity is determined by the diameter of the top jet hole, the number of the jet holes and the top jet speed, a better tip leakage flow control effect cannot be obtained by an undersize air injection quantity, the efficiency of a compressor (or a turbine) can be reduced by an oversize air injection quantity, and the reduction of the air injection quantity is the main direction of the design of the top jet hole under the condition of ensuring the control effect of tip leakage flow.

The air inlet holes on the front edge of the blade change the structure of the front edge of the blade, so that the flow field in the blade machine (a compressor or a turbine) can be disturbed to a certain extent, and the stability and the working efficiency of the blade machine are influenced. The design of the structure, the aperture, the quantity, the distribution and the like of the air inlet holes at the front edge needs to consider the negative effect brought by the air inlet holes and the air injection quantity required by inhibiting the tip leakage flow at the blade top.

The air inlet hole on the front edge of the blade is of an expansion structure facing the incoming flow direction, so that the effective flow area under the condition of different incoming flow attack angles can be increased without increasing the aperture, the loss of a large amount of momentum is avoided, and the suction of fluid is facilitated.

The air inlet holes at the front edge of the blade are distributed on the front stagnation point of the front edge of the blade under the design working condition, so that the large inflow suction volume and the small air inlet loss can be expected to be obtained under various working conditions.

The distribution position of the air inlet holes on the front edge of the blade in the spanwise direction influences the energy of the incoming airflow and the structural design of the internal cavity. The distribution area of the air inlet hole is close to the blade tip, so that the incoming airflow with larger energy and momentum can be obtained, the stroke of the internal cavity is shortened, the loss along the stroke is reduced, but the airflow turning curvature in the cavity is large, so that larger flow loss is possibly caused; the proximity of the distribution of the inlet holes to the vanes may reduce flow losses by reducing the turning curvature of the air flow within the chamber, but may increase the travel of the internal chamber and increase losses along the way. Therefore, the distribution position design of the air inlet holes at the front edge of the blade needs to be considered comprehensively, and the distribution position can be determined after numerical simulation is carried out by utilizing a CFD (computational fluid dynamics) technology.

The design of the inner cavity of the blade can be flexibly adjusted according to the design of the air inlet hole and the air injection hole. The blade cavity is closely matched with the air inlet hole and the air injection hole, so that the volume of the cavity inside the blade can be minimized, and the strength and the service life of the blade can be improved; the design of the cavity flow channel avoids large local loss, reduces the total pressure loss of airflow in the cavity flow channel, is beneficial to improving the pressure difference between the air jet hole at the blade top and the blade tip gap, improves the air jet airflow momentum at the blade top and obtains better blade tip leakage flow inhibiting effect.

After the self-adaptive air injection structure is adopted, the leakage ratio of the blade cascade (the leakage ratio is defined as the ratio of the mass flow of the tip leakage flow to the mass flow of the inlet of the blade cascade and is used for measuring the inhibition effect of the self-adaptive air injection structure on the leakage flow) is reduced to 1.50 percent from 1.58 percent of a prototype, and meanwhile, the mass flow flowing through the through hole only accounts for 0.038 percent of the main flow. The structure in the embodiment of the invention effectively weakens the tip leakage flow and reduces the tip leakage flow rate.

Drawings

FIG. 1 is a meridional view of a leading edge self bleed air and tip self adaptive air jet stator blade.

FIG. 2 is a bottom view of the leading edge self bleed air and tip adaptive air injection stator blade, taken from section 2-2 of FIG. 1.

Fig. 3 is a cross-sectional view of 3-3 of fig. 1.

Fig. 4 is a cross-sectional view 4-4 of fig. 3.

FIG. 5 is a partial enlarged view of the tip of the blade at the air injection hole.

Fig. 6 is a graph comparing the flow rates of leakage flows at the tip clearances of the prototype cascade and the cascade to which the leading edge self bleed air and tip adaptive jet structures were applied in the example, (a) the prototype cascade, and (b) the cascade to which the leading edge self bleed air and tip adaptive jet structures were applied.

Description of the reference numerals: 1. a leaf body; 2. a blade leading edge; 3. a blade trailing edge; 4. leaf tops; 5. a hub; 6. blade tip clearance; 7, a blade pressure surface; 8. a blade suction surface; 9a. An incoming gas; 9b. Gas flowing into the vanes; 9c, tip leakage flow; 10. a blade leading edge air inlet hole; 11. a blade internal cavity; 12. and (4) blade top air injection holes.

Detailed Description

The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

In the embodiment, a certain blade cascade primitive is taken as a research object, and the geometric parameters of the blade cascade are shown in table 1. The blade is provided with a front edge air inlet hole, an internal cavity and a blade top air jet hole, so that the effects of self-air-entraining from the front edge of the blade and self-adaptive air jet at the blade top are achieved, and the passive control is formed on the tip leakage flow.

TABLE 1 certain cascade design geometry parameters

As shown in fig. 1, the present embodiment mainly comprises a blade body 1, a blade leading edge air inlet hole 10, a blade inner cavity 11 and a blade top air injection hole 12.

In the process of the airflow flowing through the stationary blade 1, the pressure intensity of the airflow close to the pressure surface 7 of the blade is greater than the pressure intensity of the airflow close to the suction surface 8 of the blade, and the pressure difference between the suction surface and the pressure surface and the flow path provided by the tip clearance 7 cause the airflow 9a at the blade tip to flow from the pressure surface 7 of the blade to the suction surface 8 of the blade through the tip clearance 6 to form a tip leakage flow 9c, and the tip leakage flow 9c can bring influences such as efficiency loss and blockage to the engine. In this embodiment, the tip gas injection holes 12 at the tip 4 can inject the gas 9b, and the tip leakage flow 9c is suppressed at the tip clearance 6. The control effect of the embodiment on the tip leakage flow is changed along with the change of the incoming flow speed 9a, the incoming flow speed 9a is increased, the larger the momentum of the introduced airflow 9b is, the energy of the gas 9b ejected from the blade tip is increased, and the sealing effect of the blade tip jet at the blade tip gap 6 is enhanced. Therefore, the present embodiment has self-adaptability to the control effect of the tip leakage flow.

Whether the airflow 9b flowing into the blade can be ejected from the blade top air injection holes 12 or not is mainly overcome by the static pressure of the airflow at the blade tip clearance 6. For an axial flow compressor, the axial flow compressor is mainly pressurized along the axial direction, the airflow at the front section of the blade tip of the axial flow compressor is not fully pressurized, and the stagnation pressure of the incoming flow gas at the front edge of the blade is greater than the static pressure at the gap of the blade tip; for the turbine, airflow flows along the same pressure, and the stagnation pressure of the incoming airflow at the blade front edge is also larger than the static pressure at the blade tip clearance, so the pressure difference formed by the stagnation pressure of the airflow at the blade front edge and the static pressure at the blade tip clearance can provide driving force for the self-bleed air and the self-adaptive flow path. When the blade 1 is formed by a through hole structure for communicating the blade front edge 2 with the blade top 4, the incoming airflow 9b flows in from the blade front edge air inlet 10, the flowing in the blade internal cavity 11 realizes speed reduction and pressure increase, and the pressure higher than the static pressure of the blade tip clearance 6 is obtained, namely the driving force of the internal cavity airflow 9b ejected from the blade top air jet hole 12 is obtained, so that the airflow 9b can flow through the blade internal cavity 11, finally the airflow 9b is ejected from the blade top air jet hole 12, the sealing effect is achieved at the blade tip clearance 6, and the blade tip leakage flow 9c is inhibited.

As shown in fig. 1-4, the blade front edge 2 is provided with a blade front edge air inlet hole 10, and the blade front edge air inlet hole 10 changes the structure of the blade front edge 2, and disturbs the flow field inside the blade machine (compressor or turbine) to a certain extent, and affects the stability and the working efficiency of the blade machine, so the design of the blade front edge air inlet hole needs to consider the negative effect brought by the blade front edge air inlet hole and the air injection amount required by inhibiting the tip leakage flow at the blade tip.

As shown in fig. 1-4, the vane leading edge 2 of the present embodiment is provided with two leading edge air inlets 10, the number of the actual leading edge air inlets may be more or less according to the actual situation, and the number of the leading edge air inlets is determined by the air injection amount required by the air injection holes, the negative influence of the control leading edge air inlets on the flow field, and the influence on the vane strength. The distribution position of the air inlet guide vane is at the front stagnation point of the vane, and the air inlet guide vane is expected to obtain larger inflow suction volume and smaller air inlet loss under various working conditions.

The distribution position of the air inlet holes on the front edge of the blade in the spanwise direction influences the energy of the incoming airflow and the structural design of the internal cavity, and influences the structural strength of the blade. The air inlet distribution area is close to the blade tip, so that the stroke of the internal cavity can be shortened, the loss along the stroke can be reduced, but the airflow turning curvature in the cavity is large, and the large flow loss can be caused; the proximity of the inlet distribution area to the vanes may reduce flow losses by reducing the turning curvature of the airflow within the chamber, but may increase the travel of the internal chamber and increase losses along the path. Therefore, the distribution position design of the air inlet holes at the front edge of the blade needs to be considered comprehensively, the air inlet holes are arranged at the positions with 60-90% of the blade height and can be distributed at equal intervals, and the distribution positions can be determined after numerical simulation is carried out by utilizing a CFD (computational fluid dynamics) technology.

As shown in the enlarged partial view I in fig. 1, the air inlet 10 has an expanding structure facing the incoming flow direction, so that the effective flow area under different incoming flow attack angles can be increased without increasing the size of the internal cavity 11 of the vane, thereby avoiding a large amount of momentum loss and facilitating the suction of fluid.

The incoming flow gas 9b sucked in from the air inlet hole 10 at the front edge of the blade passes through the cavity 11 in the blade and is sprayed out from the gas jet hole 12 at the top of the blade. The size of the air injection quantity is determined by the diameter of the top jet hole, the number of the jet holes and the top jet speed, a better tip leakage flow control effect cannot be obtained by an undersize air injection quantity, the efficiency of a compressor (or a turbine) can be reduced by an oversize air injection quantity, and the reduction of the air injection quantity is the main direction of the design of the top jet hole under the condition of ensuring the control effect of tip leakage flow. As shown in fig. 2, the blade tip 4 of the present embodiment is provided with two tip gas injection holes 12.

The distribution positions of the blade top holes can be arranged along the mean camber line, and the strength of the blade is ensured.

The jet holes 12 are distributed at the position of 10-40% of axial chord length, the position distribution of the blade top jet holes 12 can influence the inhibition effect of the blade tip leakage flow 9c, the jet holes are arranged near the initial region of the blade tip leakage vortex to hopefully weaken the strength of the blade tip leakage vortex, or the initial position of the blade tip leakage vortex is moved backwards, and the effect of improving the flow field is achieved by shortening the effective blending distance of the blade tip leakage vortex and the main flow; the jet holes are arranged in the area with high tip leakage flow strength, so that the tip leakage flow strength is expected to be better weakened, and the tip leakage flow rate is reduced. The distribution position of the blade tip leakage flow under different working conditions and the corresponding control effect are considered, and the effect that blade tip leakage can be well inhibited by blade tip air injection under different working conditions is achieved. The CFD technology is used for researching the blade tip leakage flow of the blade, so that the distribution conditions of the blade tip leakage flow and the blade tip leakage vortex can be judged in advance, the position distribution of the blade top air injection holes can be reasonably arranged, the CFD technology is further used for researching the control effect of the control method, and the optimal position distribution of the blade top air injection holes is expected to be determined after repeated iteration.

As shown in fig. 5, the air injection direction of the blade top air injection hole 12 is opposite to the circumferential direction of the blade tip leakage flow 9c in the circumferential direction, that is, the direction is directed to the suction surface 8 along the pressure surface 7 and forms a certain angle with the chord direction of the blade, because the change of the air injection direction of the blade top affects the control effect on the blade tip leakage flow, when the air injection direction is opposite to the flow direction of the blade tip leakage flow 9c, the control effect of the air injection is good, and the sealing effect can be effectively achieved to suppress the blade tip leakage flow. The nozzle structure of the blade top air injection hole 12 in the embodiment adopts a contraction nozzle, so that the air injection speed can be increased, the air flow momentum can be increased, and the effect of better inhibiting the blade tip leakage flow can be achieved by using smaller air injection quantity.

The structure of the blade inner cavity 11 is flexibly adjusted according to the design of the air inlet hole 10 and the air injection hole 12, and the blade cavity is closely matched with the air inlet hole and the air injection hole, so that the hollowed-out volume of the blade 1 can be minimized, and the strength and the service life of the blade 1 can be improved; the cavity design avoids large local loss, can reduce the total pressure loss of air flow in the cavity, is beneficial to improving the pressure difference between the air jet hole 12 at the top of the blade and the clearance 4 at the blade tip, improves the momentum of air jet at the top of the blade and better inhibits the leakage flow 9c at the blade tip. In this embodiment, the blade inner cavity 11 is vertically arranged along the blade height direction, two shunts are arranged at the upper end of the blade towards the front edge side of the blade, the shunts are respectively led to the two front edge air inlets 10 of the blade, and the bottom end of the blade inner cavity is located right above the top air injection hole of the blade.

Fig. 6 is a graph showing a comparison of the flow rate of the leakage flow at the tip clearance of the prototype cascade and the cascade using the leading edge self bleed air and tip adaptive jet configurations in this example. Under the working condition, the Mach number maximum point of the blade tip region of the prototype blade grid is located on one side of the pressure surface, and the Mach number maximum point is driven by the pressure difference between the pressure surface and the suction surface of the blade, so that the airflow flows from the pressure surface to the suction surface at the gap, and the airflow close to the pressure surface side is expanded by the flow channel when flowing into the blade tip gap, and the accelerated pressure reduction process occurs, so that the flow velocity of the tip leakage flow on the pressure surface side at the gap is the maximum, and the leakage flow intensity of the region is also the maximum. The leakage flow speed of the blade cascade applying the leading edge self-bleed air and the blade top self-adaptive air injection structure in the area near the blade top air injection hole is obviously reduced, because the airflow sprayed from the blade top air injection hole forms a blocking area in the blade tip gap, and the blocking area can weaken the strength of the blade tip leakage flow from the pressure side to the suction side, so that the sealing effect is achieved. After the self-adaptive jet structure is adopted, the leakage ratio of the blade cascade (the leakage ratio is defined as the ratio of the mass flow of the tip leakage flow to the mass flow of the inlet of the blade cascade and is used for measuring the inhibition effect of the self-adaptive jet structure on the leakage flow) is reduced to 1.50% from 1.58% of a prototype, and meanwhile, the mass flow flowing through the through hole only accounts for 0.038% of the main flow. The structure in the embodiment effectively weakens the tip leakage flow and reduces the tip leakage flow rate.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims (10)

1. The utility model provides a stator blade of leading edge self bleed air and jet-propelled of blade top self-adaptation which characterized in that: the stator blade is internally provided with a flow channel, the flow channel comprises a blade front edge air inlet hole, a blade top air injection hole and an internal cavity, incoming air flow sucked from the blade front edge air inlet hole flows to the blade top air injection hole through the internal cavity of the blade, and is injected to a stator blade tip gap from the blade top air injection hole.

2. The stator blade for leading edge self-bleed air and tip self-adaptive air injection of claim 1, wherein: the blade top air injection holes are arranged near the initial region of the blade tip leakage vortex or near the region with the maximum blade tip leakage strength.

3. The stator blade for leading edge self-bleed air and tip self-adaptive air injection of claim 2, wherein: the blade top gas injection holes are distributed along the blade profile mean camber line, and the number of the gas injection holes is 1-3.

4. The stator blade for leading edge self-bleed air and blade tip self-adaptive air injection of claim 3, wherein: the aperture of the blade top gas injection hole accounts for 20-40% of the thickness of the blade top.

5. The stator blade for leading edge self-bleed air and tip self-adaptive air injection of claim 4, wherein: the jet angle of the blade top jet hole is opposite to the direction of leakage flow in the circumferential direction.

6. The stator blade with leading edge self-bleed air and blade tip self-adaptive air injection according to any one of claims 1 to 5, wherein: the blade top air injection hole structure adopts a contraction nozzle.

7. The stator blade for leading edge self-bleed air and blade tip self-adaptive air injection of claim 1, wherein: the air inlet holes of the front edge of the blade are distributed on the front stagnation point under the design working condition of the front edge of the blade.

8. The stator blade for leading edge self-bleed air and tip self-adaptive air injection of claim 7, wherein: the air inlet holes at the front edge of the blade are distributed at the positions with 60-90% of the blade height, the number of the air inlet holes is 1-3, and the air inlet holes are distributed at equal intervals.

9. The stator blade for leading edge self-bleed air and tip self-adaptive air injection of claim 8, wherein: the aperture of the air inlet hole at the front edge of the blade accounts for 20-50% of the small diameter of the front edge of the blade.

10. Stator blade with leading edge self-bleed air and tip adaptive air injection according to any of claims 7-9, characterized in that: the air inlet hole at the front edge of the blade is of an expansion structure facing the incoming flow direction, and the expansion angle is 0-5 degrees.

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