A pressure reducing throttle pre-swirl nozzle device for a pre-swirl air supply system

Abstract

The present application relates to the technical field of aero-engine pre-rotation air supply system application, in particular to a pressure-reducing throttling pre-rotation nozzle device for a pre-rotation air supply system. The pre-rotation nozzle comprises a nozzle outer ring and a nozzle inner ring, and the nozzle outer ring and the nozzle inner ring are provided with a nozzle outer ring grate and a nozzle inner ring grate in the ring cavity therebetween, and the nozzle outer ring grate and the nozzle inner ring grate form a pressure-reducing ring cavity. The device reduces the air inlet pressure and flow of the pre-rotation air supply system through the nozzle outer ring grate, the nozzle inner ring grate and the pressure-reducing ring cavity, and maintains the good performance of the pre-rotation nozzle. The device has a simple structure, low processing difficulty and convenient installation, effectively reduces the air inlet pressure and flow of the pre-rotation air supply system, meets the air supply requirements of the pre-rotation air supply system, ensures the air supply uniformity, and improves the overall performance and reliability of the aero-engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of the application of aero-engine pre-rotation air supply system, and particularly relates to a pressure-reducing throttling pre-rotation nozzle device for a pre-rotation air supply system. BACKGROUND

[0002] The aero-engine has always been praised as the "pearl" on the crown of the aviation industry, and has become an important symbol of a country's scientific and technological strength, industrial level, military power and comprehensive national power. The future development direction of the aero-engine is large thrust-to-weight ratio, low oil consumption rate and high safety and reliability. Generally speaking, under the condition that the size of the engine remains unchanged, the thrust can be increased by 10% for every 50K increase in the temperature before the turbine. Therefore, increasing the temperature before the turbine is of great significance for improving the performance of the aero-engine. However, the excessively high temperature before the turbine also brings extremely severe challenges to the entire aero-engine, which specifically manifests in that the working environment of the engine deteriorates sharply, thereby causing the reliability of the engine to decrease and the service life to be shortened. Especially, the maximum stress of the turbine rotor blade is likely to exceed the allowable limit of the material in the harsh environment of high temperature and high speed. Therefore, high-efficiency cooling technology must be developed to reduce the adverse effects caused by the rapid increase in the temperature before the turbine and to ensure that the high-speed turbine rotor blade can operate stably for a long time at high temperature. The pre-rotation air supply system is responsible for providing high-quality cold gas for the turbine rotor blade to meet the flow requirements and pressure conditions, so as to reduce the amount of cooling gas by improving the quality of the cooling gas. The pre-rotation air supply system designed with care can make the temperature of the cold gas drop by as much as 100K, which has a significant effect on the main stream cooling.

[0003] The cooling principle of the pre-rotation air supply system is to accelerate the airflow by the pre-rotation nozzle and form a large circumferential velocity component, so as to reduce the relative velocity between the airflow static temperature and the rotor disc, thereby achieving the purpose of reducing the relative total temperature of the airflow. Up to now, different types and different functions of pre-rotation air supply systems have been developed for the research and development of the pre-rotation air supply system. According to the inlet direction of the nozzle, the pre-rotation air supply system can be divided into a radial pre-rotation air supply system and an axial pre-rotation air supply system; according to the relative height of the nozzle and the air supply hole, the pre-rotation air supply system can be divided into a high-position pre-rotation air supply system and a low-position pre-rotation air supply system; and according to whether there is a cover plate disc element, the pre-rotation air supply system can be divided into a direct pre-rotation air supply system and a cover plate pre-rotation air supply system. When selecting the type of the pre-rotation air supply system, the designer needs to comprehensively consider factors such as the type and size of the engine. The air supply objects and functions of the pre-rotation air supply system are also different, some of which provide cold gas for the turbine rotor blade, some of which provide cold gas for the rim seal of the turbine disc after the blade mortise, and some of which provide cold gas for the turbine disc.

[0004] From the effect of cooling, the more cooling air is used, the better the effect is, but the cooling air extracted from the compressor will not work in the turbine, which will reduce the thrust generated by the engine, so the amount of bleed air of the pre-rotation air supply system will directly affect the performance of the whole machine. Research shows that, when the amount of bleed air of the pre-rotation air supply system increases by 1%, the engine thrust is about 2% less, the fuel consumption rate increases by 0.7%~0.9% when the flight Mach number is less than 1.2, and the fuel consumption rate increases by 1.2%~1.4% when the flight Mach number is higher than 1.2. Taking a high-bypass-ratio turbofan engine as the research object, the turbine cooling algorithm considering the amount of cold air and the efficiency loss of cooling is introduced into the whole machine performance calculation model, and it is found that if the amount of cold air is reduced by 20%, the unit thrust of the engine can be increased by 3%, and the specific fuel consumption can be reduced by 0.9%, so reducing the amount of cold air is an effective method to improve the performance of the engine.

[0005] In the prior art, for the pre-rotation air supply system for providing cooling air for the rim seal behind the turbine disc, the system pressure ratio of the system is relatively large, between 1.8~1.9, but the air supply flow is relatively small, between 20g / s~62g / s, which leads to that the total area and the number of the pre-rotation nozzle throat of the pre-rotation air supply system are too small, the total area of the nozzle throat is 30mm 2 ~85mm 2 , and the number of the nozzle is 4~8. Too small nozzle throat area will lead to difficult machining and high machining cost of the pre-rotation nozzle, and too few nozzle numbers will cause uneven flow and pressure distribution at the outlet of the bleed air nozzle, so that the flow and pressure of the cold air entering the mortise are unevenly distributed in the circumferential direction, the cooling effect of the mortise is poor, in addition, the flow and pressure of the cold air for the rim seal behind the turbine disc are also unevenly distributed in the circumferential direction, and the rim seal effect is also poor, thereby increasing the risk of main flow gas intrusion.

[0006] The present application provides a pressure-reducing throttling pre-rotation nozzle device for a pre-rotation air supply system, which increases the number and total area of the pre-rotation nozzle, and reduces the inlet pressure and flow of the pre-rotation air supply system. SUMMARY

[0007] The present application aims to avoid the shortcomings of the prior art, and provides a pressure-reducing throttling pre-rotation nozzle device for a pre-rotation air supply system, which can reduce the inlet pressure of the pre-rotation air supply system, reduce the inlet flow, thereby increasing the number and area of the pre-rotation nozzle, reducing the machining difficulty, ensuring the circumferential uniform air supply of the system, and improving the overall performance and reliability of the system.

[0008] In order to achieve the above object, the technical scheme adopted by the present application is: the pre-rotation throttle nozzle device for the pre-rotation air supply system, characterized in that the pre-rotation nozzle comprises a nozzle outer ring and a nozzle inner ring, and the nozzle outer ring and the nozzle inner ring are correspondingly provided with a nozzle outer ring grate and a nozzle inner ring grate in the ring cavity between the nozzle outer ring and the nozzle inner ring, and the nozzle outer ring grate and the nozzle inner ring grate form a pressure reduction ring cavity.

[0009] Further, the nozzle outer ring is further provided with a flange, the nozzle outer ring grate and the nozzle inner ring form a first-stage ring gap, the nozzle inner ring grate and the nozzle outer ring grate form a second-stage ring gap, the air flow passes through the first-stage ring gap and is reduced in pressure and flow rate, then enters the pressure reduction ring cavity, forms a vortex at the position, increases the flow resistance, realizes the throttling effect, and then passes through the second-stage ring gap and is reduced in pressure and flow rate again.

[0010] Further, the nozzle inner ring and the nozzle outer ring are assembled through interference fit, and the interference fit amount is 0.05mm-0.15mm.

[0011] Further, the nozzle inner ring and the nozzle inner ring grate adopt an integrated structure, the flange, the nozzle outer ring and the nozzle outer ring grate adopt an integrated structure, and the flange is connected and fixed with the engine case support ring.

[0012] Further, the nozzle outer ring grate has an inclination angle delta 1 in the range of 33°-45°, and a height H 1 in the range of 6.5mm-7.0mm, the nozzle inner ring grate has an inclination angle delta 2 in the range of 35°-57°, and a height H 2 in the range of 4.5mm-5mm; the nozzle outer ring grate and the nozzle inner ring grate are both inclined to the direction of the inlet air flow.

[0013] Further, the pre-rotation nozzle has a pre-rotation deflection angle theta in the range of 10°-20°, the pre-rotation deflection angle refers to the included angle between the pre-rotation nozzle outlet deflection direction and the circumferential direction, the deflection direction of the pre-rotation nozzle is consistent with the rotation direction of the turbine disc, the pre-rotation nozzle adopts a slanted hole flow channel formed by the blade pressure surface and the blade suction surface and inclined to the nozzle ring in equal intervals in the circumferential direction, the nozzle flow channel deflection profile is tapered, and the minimum throat area is reached at the pre-rotation nozzle outlet.

[0014] Further, the first-stage ring gap has a width b 1 in the range of 0.1-0.25mm, and the second-stage ring gap has a width b 2 in the range of 0.1-0.2mm, and the first-stage ring gap is located upstream of the air flow.

[0015] Further, the pre-rotation nozzle has a total throat area Ais determined by the following formula,

[0016] ,

[0017] wherein, m is the mass flow rate of the gas supply; C d is the flow coefficient of the pre-swirl nozzle, C d and has a value range of 0.80-0.95; in , p out respectively, are the total pressure at the inlet of the pre-swirl nozzle and the static pressure at the outlet of the pre-swirl nozzle; in is the total temperature of the gas flow at the inlet of the pre-swirl nozzle; k is the adiabatic index of the gas flow at the inlet of the pre-swirl nozzle; R g is the gas constant, and is 287 J / (kg•K);

[0018] The nozzle grid spacing of the pre-swirl nozzle t is determined by the following formula,

[0019] ,

[0020] wherein A is the total area of the throat of the pre-swirl nozzle; N is the number of pre-swirl nozzles; theta is the pre-swirl angle;

[0021] The nozzle grid spacing t has a value range of 10mm-20mm, which determines the value of the number of pre-swirl nozzles N .

[0022] Further, the nozzle blade height h of the pre-swirl nozzle is determined by the following formula,

[0023] ,

[0024] The nozzle blade height h has a range of 5mm-10mm.

[0025] Compared with the prior art, the application has the following technical effects: the pressure relief throttle pre-rotation nozzle device for the pre-rotation air supply system reduces the air inlet pressure and flow of the pre-rotation air supply system through the pre-rotation nozzle, the nozzle outer ring grate, the nozzle inner ring grate and the pressure relief ring cavity, and the device does not change the shape and position of the pressure surface and the suction surface of the pre-rotation nozzle, so that the acceleration and flow performance of the pre-rotation nozzle are not adversely affected, and the good performance of the pre-rotation nozzle is maintained. The device has simple structure, low processing difficulty and convenient installation, effectively reduces the air inlet pressure and flow of the pre-rotation air supply system, meets the air supply amount requirement of the pre-rotation air supply system, ensures the air supply uniformity, and improves the overall performance and reliability of the aero-engine. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a meridian section view of the application;

[0027] Figure 2 is an assembly schematic view of the nozzle inner ring and the nozzle outer ring of the application;

[0028] Figure 3 is a schematic view of the nozzle inner ring structure of the application;

[0029] Figure 4 is a schematic view of the nozzle outer ring structure of the application;

[0030] Figure 5 is a velocity streamline diagram in front of the nozzle of the application;

[0031] Figure 6 is a velocity streamline diagram in the nozzle of the application.

[0032] In the figure: 1, nozzle outer ring; 2, nozzle inner ring; 3, pre-rotation nozzle; 4, nozzle outer ring grate; 5, nozzle inner ring grate; 6, pressure relief ring cavity; 7, first-stage ring gap; 8, second-stage ring gap; 9, flange. DETAILED DESCRIPTION

[0033] The principles and characteristics of the application are described below in combination with the drawings; the examples are only used to explain the application; and are not used to limit the scope of the application.

[0034] In order to achieve the above-mentioned purpose; the application provides the following specific embodiments:

[0035] Example 1: as Figure 1As shown, a kind of pressure-reducing throttle pre-whirl nozzle device for pre-whirl air supply system, its characteristics are that pre-whirl nozzle 3 includes nozzle outer ring 1 and nozzle inner ring 2, nozzle outer ring 1 and nozzle inner ring 2 are correspondingly provided with nozzle outer ring grate 4 and nozzle inner ring grate 5 in the ring cavity between nozzle outer ring 1 and nozzle inner ring 2, nozzle outer ring grate 4 and nozzle inner ring grate 5 form pressure-reducing ring cavity 6, and vortex is formed in the pressure-reducing ring cavity by air flow, so that the inlet pressure is reduced, and flow resistance is also increased, to achieve the effect of throttling.

[0036] Flange 9 is further provided on nozzle outer ring 1, first-stage ring gap 7 is formed between nozzle outer ring grate 4 and nozzle inner ring 2, second-stage ring gap 8 is formed between nozzle inner ring grate 5 and nozzle outer ring grate 4, the pressure and flow of air flow are reduced after flowing through first-stage ring gap 7, then enter the pressure-reducing ring cavity, vortex is formed at this point, flow resistance is increased, to achieve the effect of throttling, then pass through second-stage ring gap 8, the pressure and flow are reduced again, finally, the flow and pressure of air flow meet the air supply requirements, and the uniformity of air supply is ensured.

[0037] Nozzle inner ring 2 and nozzle outer ring 1 are assembled with interference fit, and the interference fit amount is 0.05mm~0.15mm.

[0038] Nozzle inner ring 2 and nozzle inner ring grate 5 adopt an integrated structure, flange 9, nozzle outer ring 1 and nozzle outer ring grate 4 adopt an integrated structure, and flange 9 is connected and fixed with engine case support ring.

[0039] The inclination angle of nozzle outer ring grate 4 delta 1 is in the range of 33°~45°, and the height H 1 is in the range of 6.5mm~7.0mm, the inclination angle of nozzle inner ring grate 5 delta 2 is in the range of 35°~57°, and the height H 2 is in the range of 4.5mm~5mm; nozzle outer ring grate 4 and nozzle inner ring grate 5 are both inclined to the direction of incoming air flow.

[0040] The pre-whirl deflection angle of pre-whirl nozzle 3 theta is in the range of 10°~20°, and the pre-whirl deflection angle refers to the included angle between the deflection direction of pre-whirl nozzle outlet and the circumferential direction, the deflection direction of pre-whirl nozzle 3 is consistent with the rotation direction of turbine disc, pre-whirl nozzle 3 adopts blade pressure surface and blade suction surface to form inclined hole flow channel which is deflected along the equidistant circumferential direction of nozzle ring, the deflection profile of nozzle flow channel is tapered, and the minimum throat area is reached at the outlet of pre-whirl nozzle.

[0041] The width of first-stage ring gap 7 b 1 is in the range of 0.1~0.25mm, and the width of second-stage ring gap 8 b 2 is in the range of 0.1~0.2mm, and first-stage ring gap 7 is located upstream of air flow.

[0042] Total throat area of ​​pre-swirling nozzle 3 A Determined by the following formula,

[0043] ,

[0044] In the formula, m For gas supply quality flow rate; C d The pre-swirling nozzle flow coefficient is... C d The value range is 0.80~0.95; in , p out These are the total pressure at the inlet of the pre-swirling nozzle and the static pressure at the outlet of the pre-swirling nozzle, respectively. in The total temperature of the airflow at the inlet of the pre-swirling nozzle; k The adiabatic index of the inlet airflow of the pre-swirling nozzle; R g The gas constant is 287 J / (kg•K);

[0045] like Figure 3 As shown, the nozzle grid spacing of the pre-swirl nozzle 3 t Determined by the following formula,

[0046] ,

[0047] In the formula, A is the total area of ​​the pre-swirling nozzle throat; N This refers to the number of pre-swirling nozzles; theta Pre-rotation angle;

[0048] Nozzle grid pitch t The value range is 10mm~20mm, which determines the number of pre-swirl nozzles. N The value of .

[0049] The nozzle blade height h of the pre-swirling nozzle 3 is determined by the following formula:

[0050] ,

[0051] The nozzle blade height h ranges from 5mm to 10mm.

[0052] In practical implementation, taking the perforated pre-swirl nozzle as an example, the pre-swirl angle is 15°. The pre-swirl nozzle is designed based on the boundary conditions of the pre-swirl air supply system. Table 1 shows the boundary conditions of the pre-swirl air supply system with a relatively large system pressure ratio and a relatively small air supply flow rate, where the inlet airflow adiabatic index is... k It is 1.3443.

[0053] Table 1 Boundary conditions for the pre-swirl gas supply system

[0054]

[0055] The total area A of the throat of the pre-swirl nozzle, the nozzle grid distance t and the nozzle blade height h can be calculated by the formula, wherein the flow coefficient of the pre-swirl nozzle is C d 0.935 is taken.

[0056] Table 2 is two design schemes of different pre-swirl nozzle numbers. As can be seen from Table 2, in the design scheme with 24 nozzle numbers, the nozzle height is only 2.58 mm, and the nozzle grid distance t is 5.16 mm, which is too small in size, difficult to process and high in processing cost. In the design scheme with 4 nozzle numbers, although the nozzle height and the grid distance are within a reasonable range, the number of nozzles is too small, which will cause uneven air supply, thereby reducing the rim seal effect and increasing the risk of gas intrusion.

[0057] Table 2 is two design schemes of different pre-swirl nozzle numbers. As can be seen from Table 2, in the design scheme with 24 nozzle numbers, the nozzle height is only 2.58 mm, and the nozzle grid distance t is 5.16 mm, which is too small in size, difficult to process and high in processing cost. In the design scheme with 4 nozzle numbers, although the nozzle height and the grid distance are within a reasonable range, the number of nozzles is too small, which will cause uneven air supply, thereby reducing the rim seal effect and increasing the risk of gas intrusion.

[0058]

[0059] If the pressure-reducing throttling pre-swirl nozzle device of the application is selected for design, the total pressure of the nozzle inlet of the device can be reduced to 333.5 kPa, and the flow coefficient of the nozzle p C d is reduced to 0.80.

[0060] Table 3 is the design result. As can be seen, compared with the design scheme of the traditional blade-hole pre-swirl nozzle, the pre-swirl nozzle throat total area, nozzle height and nozzle grid distance of the application can be all improved to a reasonable range, which is beneficial to processing and installation, and can also increase the number of nozzles to ensure the uniformity of air supply.

[0061] Table 3 is two design schemes of different pre-swirl nozzle numbers. As can be seen from Table 2, in the design scheme with 24 nozzle numbers, the nozzle height is only 2.58 mm, and the nozzle grid distance t is 5.16 mm, which is too small in size, difficult to process and high in processing cost. In the design scheme with 4 nozzle numbers, although the nozzle height and the grid distance are within a reasonable range, the number of nozzles is too small, which will cause uneven air supply, thereby reducing the rim seal effect and increasing the risk of gas intrusion.

[0062]

[0063] The boundary conditions of the pre-swirl air supply system are given according to the data in Table 1, the pre-swirl air supply system is designed according to the geometric structure parameters in Table 3, the pressure-reducing throttling pre-swirl nozzle device of the application is simulated by CFD, the air supply flow meets the design requirements, and the velocity streamline diagram before the pre-swirl nozzle as shown in Figure 1 , and the velocity streamline diagram in the nozzle as shown in Figure 2 can be obtained. As can be seen, obvious vortex is formed in the air flow in the pressure-reducing ring cavity and behind the grid, which can achieve the effect of pressure-reducing throttling. The inlet air of the nozzle is uniform, there is no vortex in the air flow in the nozzle, the flow loss is small, and the air flow at the nozzle outlet is also relatively uniform, which has good air supply uniformity.

[0064] Reference is made to Figures 4-6 ​In the processing of the pre-rotation nozzle disc, the nozzle inner ring 2 and the nozzle outer ring 1 are processed separately, 24 leaf hole type pre-rotation nozzles are uniformly distributed on the nozzle inner ring in the circumferential direction, the nozzle inner ring grate is also integrally processed with the nozzle inner ring, and the nozzle outer ring grate is integrally processed with the nozzle outer ring. When assembling, an interference fit of 0.1mm in diameter between the nozzle inner ring and the nozzle outer ring is ensured, the nozzle outer ring is nested on the nozzle inner ring by using the method of heating the outer ring.

[0065] The application is a pressure reducing throttle pre-rotation nozzle device for a pre-rotation gas supply system, which is simple and convenient in processing and installation. The nozzle inner ring grate 5 and the nozzle inner ring 2 are integrally processed, then the nozzle outer ring is processed, and the nozzle outer ring grate is integrally processed with the nozzle outer ring. When assembling, the nozzle outer ring is nested on the nozzle inner ring.

[0066] The above description is only the preferred embodiment of the application; it is not intended to limit the application; any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A pressure-reducing and throttling pre-swirl nozzle device for a pre-swirl gas supply system, characterized in that: The pre-swirl nozzle includes an outer nozzle ring and an inner nozzle ring. The outer nozzle ring and the inner nozzle ring are respectively provided in the annular cavity between them. The outer nozzle ring and the inner nozzle ring form a pressure-reducing annular cavity. The outer ring of the nozzle and the inner ring of the nozzle form a first-stage annular gap, and the inner ring of the nozzle and the outer ring of the nozzle form a second-stage annular gap. After the airflow passes through the first-stage annular gap, the pressure and flow rate decrease, and then it enters the pressure-reducing annular cavity, where a vortex is formed, increasing the flow resistance and achieving the effect of throttling. After passing through the second-stage annular gap, the pressure and flow rate decrease again. Inclination angle of nozzle outer ring grates δ 1. The range is 33°~45°, height H 1. Size range is 6.5mm~7.0mm, nozzle inner ring grate tooth inclination angle δ 2. The range is 35°~57°, height H 2. The size range is 4.5mm~5mm; both the outer ring grate teeth and the inner ring grate teeth of the nozzle are inclined towards the direction of the incoming air flow; The pre-rotation deflection angle of the pre-rotation nozzle θ The range is 10°~20°. The pre-swirl deflection angle refers to the angle between the deflection direction of the pre-swirl nozzle outlet and the circumferential direction. The deflection direction of the pre-swirl nozzle is consistent with the rotation direction of the turbine disk. The pre-swirl nozzle uses the blade pressure surface and the blade suction surface to form an inclined flow channel with equal spacing and circumferential deflection along the nozzle ring. The deflection surface of the nozzle flow channel is gradually narrowed, and the minimum throat area is reached at the outlet of the pre-swirl nozzle. The first-level circumferential seam width b 1. Size range is 0.1~0.25mm, second-level circumferential seam width b 2. The size range is 0.1~0.2mm, and the first-stage annular gap is located upstream of the airflow.

2. The pressure-reducing and throttling pre-swirl nozzle device for a pre-swirl gas supply system as described in claim 1, characterized in that: The nozzle inner ring and nozzle inner ring grates are of an integral structure, as are the flange, nozzle outer ring and nozzle outer ring grates. A flange is also provided on the nozzle outer ring, and the flange is connected and fixed to the engine casing support ring.

3. The pressure-reducing and throttling pre-swirl nozzle device for a pre-swirl gas supply system as described in claim 1, characterized in that: The inner and outer rings of the nozzle are assembled by an interference fit, with an interference amount of 0.05mm to 0.15mm.

4. A pressure-reducing and throttling pre-swirl nozzle device for a pre-swirl gas supply system as described in any one of claims 1-3, characterized in that: The total throat area of ​​the pre-swirling nozzle A Determined by the following formula, ， In the formula, m For gas supply quality flow rate; C d The pre-swirling nozzle flow coefficient is... C d The value range is 0.80~0.95; in , p out These are the total pressure at the inlet of the pre-swirling nozzle and the static pressure at the outlet of the pre-swirling nozzle, respectively. in The total temperature of the airflow at the inlet of the pre-swirling nozzle; k The adiabatic index of the inlet airflow of the pre-swirling nozzle; R g The gas constant is 287 J / (kg•K); The nozzle grid pitch of the pre-swirl nozzle t Determined by the following formula, ， In the formula, A is the total area of ​​the pre-swirling nozzle throat; N This refers to the number of pre-swirling nozzles; θ Pre-rotation angle; Nozzle grid pitch t The value range is 10mm~20mm, which determines the number of pre-swirl nozzles. N The value of ; the nozzle blade height h of the pre-swirl nozzle is determined by the following formula, ， The nozzle blade height h ranges from 5mm to 10mm.

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