Decompression throttling prewhirl nozzle device for prewhirl air supply system

Abstract

The invention relates to the technical field of application of prewhirl air supply systems of aero-engines, in particular to a decompression throttling prewhirl nozzle device for a prewhirl air supply system. The prewhirl nozzle is characterized in that the prewhirl nozzle comprises a nozzle outer ring and a nozzle inner ring, nozzle outer ring comb teeth and nozzle inner ring comb teeth are correspondingly arranged in an annular cavity between the nozzle outer ring and the nozzle inner ring, and the nozzle outer ring comb teeth and the nozzle inner ring comb teeth form a pressure reduction annular cavity. The air inlet pressure and flow of a pre-swirl air supply system are reduced through the nozzle outer ring comb teeth, the nozzle inner ring comb teeth and the pressure reduction ring cavity, and the good performance of the pre-swirl nozzle is kept. The device is simple in structure, low in machining difficulty and convenient to install, the air inlet pressure and flow of the pre-whirl air supply system are effectively reduced, the air supply uniformity can be guaranteed while the air supply amount requirement of the pre-whirl air supply system is met, and therefore the overall performance and reliability of an aero-engine are improved.

Description

Technical Field

[0001] The invention relates to the technical field of application of a pre-swirl air supply system for an aero-engine, in particular to a decompression throttling pre-swirl nozzle device for a pre-swirl air supply system. Background Art

[0002] Aircraft engines have always been hailed as the "pearl" in the crown of the aviation industry, and have become an important symbol for measuring a country's scientific and technological strength, industrial level, military strength and comprehensive national strength. The future development direction of aircraft engines is high thrust-to-weight ratio, low fuel consumption rate and high safety and reliability. It is generally believed that under the condition that the engine size remains unchanged, the thrust can be increased by 10% for every 50K increase in the temperature before the turbine. Therefore, increasing the temperature of the gas before the turbine is extremely important for improving the performance of aircraft engines. However, the excessively high temperature before the turbine also brings extremely severe tests to the entire aircraft engine, which is specifically manifested as: the working environment of the engine deteriorates sharply, which in turn causes the reliability of the engine to decrease and the life of the engine to shorten. Especially for high-temperature components, the maximum stress of the turntable of the turbine rotor blades in the harsh environment of high temperature and high speed is easy to exceed the allowable limit of its material. Therefore, it is necessary to develop efficient cooling technology to reduce the adverse effects of the rapid increase in the temperature before the turbine, and ensure that the high-speed turbine rotor blades can also operate smoothly for a long time at high temperatures. The pre-swirl air supply system is responsible for providing high-quality cold air that meets the flow requirements and pressure conditions for the turbine rotor blades, so as to improve the quality of the cold air and reduce the amount of cooling gas. The carefully designed pre-swirl air supply system can reduce the temperature of the cold air by up to 100K, providing a significant mainstream cooling effect.

[0003] The cooling principle of the pre-swirl air supply system is to accelerate the airflow through the pre-swirl nozzle and form a larger circumferential velocity component, reduce the relative velocity between the static temperature of the airflow and the turntable, and thus achieve the purpose of reducing the relative total temperature of the airflow. The research and development of the pre-swirl air supply system has developed different types and functions of pre-swirl air supply systems. According to the nozzle air inlet direction, it can be divided into radial pre-swirl air supply system and axial pre-swirl air supply system; according to the relative height between the nozzle and the air supply hole, it can be divided into high-position pre-swirl air supply system and low-position pre-swirl air supply system; according to whether there is a cover plate disc element, it can be divided into direct pre-swirl air supply system and cover plate pre-swirl air supply system. When selecting the type of pre-swirl air supply system, the designer needs to make a comprehensive consideration based on factors such as the type and size of the engine. The air supply objects and functions of the pre-swirl air supply system are also different. Some provide cold air for the turbine rotor blades, some lead to the blade mortise and tenon to provide cold air for the rim seal behind the turbine disc, and some lead to the disc cavity to provide cold air for the turbine disc.

[0004] From the perspective of cooling effect, the more cooling air is used, the better the effect. However, the cooling air drawn from the compressor will not do work in the turbine, which will reduce the thrust generated by the engine. Therefore, the amount of air bleed from the pre-swirl air supply system will directly affect the performance of the whole machine. Studies have found that for every 1% increase in the amount of air bleed from the pre-swirl air supply system, the engine thrust will be lost by about 2%. When the flight Mach number is less than 1.2, the fuel consumption rate increases by 0.7%~0.9%, and when it is higher than 1.2, the fuel consumption rate increases by 1.2%~1.4%. Taking the high bypass ratio turbofan engine as the research object, a turbine cooling algorithm that considers the amount of cooling air and the cooling efficiency loss is introduced into the whole machine performance calculation model. It is found that if the amount of cooling air is reduced by 20%, the unit thrust of the engine can be increased by 3% and the fuel consumption rate is reduced by 0.9%. Therefore, reducing the amount of cooling air is an effective way to improve engine performance.

[0005] In the prior art, for the pre-swirl air supply system that provides cold air for the rim seal behind the turbine disk, the system pressure ratio of the system is relatively large, between 1.8 and 1.9, but the air supply flow rate is relatively small, between 20g / s and 62g / s, resulting in the total throat area and number of the pre-swirl nozzles of the pre-swirl air supply system being too small. The total throat area of ​​the nozzles is 30mm 2 ~85mm 2 , the number of nozzles is 4 to 8. If the nozzle throat area is too small, it will make the pre-swirl nozzle difficult to process and the processing cost is high. If the number of nozzles is too small, the air flow rate and pressure distribution at the outlet of the bleed nozzle will be uneven, which will lead to uneven circumferential distribution of the cold air flow and pressure entering the tenon, and the cooling effect of the tenon will be poor. In addition, it will also cause the circumferential distribution of the cold air flow and pressure used for the sealing of the rear rim of the turbine disk to be uneven, and the sealing effect of the rim will also be poor, which will increase the risk of mainstream gas intrusion.

[0006] The present invention provides a decompression throttling pre-swirl nozzle device for a pre-swirl air supply system, which reduces the air intake pressure and flow rate of the pre-swirl air supply system by increasing the number of pre-swirl nozzles and the total throat area. Summary of the invention

[0007] The purpose of the present invention is to avoid the shortcomings of the prior art and to provide a pressure-reducing and throttling pre-swirl nozzle device for a pre-swirl air supply system, which can reduce the air intake pressure of the pre-swirl air supply system and reduce the air intake flow rate, thereby increasing the number and area of ​​the pre-swirl nozzles, reducing the processing difficulty, ensuring uniform circumferential air supply in the system, and improving the overall performance and reliability of the system.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: the described pressure-reducing throttling pre-swirl nozzle device for a pre-swirl air supply system is characterized in that the described pre-swirl nozzle includes a nozzle outer ring and a nozzle inner ring, and the nozzle outer ring comb teeth and the nozzle inner ring comb teeth are correspondingly arranged in the annular cavity between the nozzle outer ring and the nozzle inner ring, and the nozzle outer ring comb teeth and the nozzle inner ring comb teeth form a pressure-reducing annular cavity.

[0009] Furthermore, a flange is provided on the outer ring of the nozzle, a first-level annular gap is formed between the comb teeth of the outer ring of the nozzle and the inner ring of the nozzle, and a second-level annular gap is formed between the comb teeth of the inner ring of the nozzle and the comb teeth of the outer ring of the nozzle. After the airflow passes through the first-level annular gap, the pressure and flow rate are reduced, and then the airflow enters the pressure reducing annular cavity, where a vortex is formed, the flow resistance is increased, and the throttling effect is achieved. Then, the airflow passes through the second-level annular gap, and the pressure and flow rate are reduced again.

[0010] Furthermore, the nozzle inner ring and the nozzle outer ring are assembled by interference fit, and the interference fit amount is 0.05mm~0.15mm.

[0011] Furthermore, the nozzle inner ring and the nozzle inner ring comb teeth adopt an integrated structure, the flange, the nozzle outer ring and the nozzle outer ring comb teeth adopt an integrated structure, and the flange is connected and fixed to the engine casing support ring.

[0012] Furthermore, the inclination angle of the outer ring grate of the nozzle is δ 1 range is 33°~45°, height H 1. The size range is 6.5mm~7.0mm, and the inclination angle of the inner ring grate of the nozzle is δ 2Range: 35°~57°, height H 2 The size range is 4.5mm~5mm; the outer ring grate teeth of the nozzle and the inner ring grate teeth of the nozzle are inclined toward the direction of the incoming air flow.

[0013] Furthermore, the pre-swirl deflection angle of the pre-swirl nozzle is 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 hole flow channel with equal intervals and circumferential deflection along the nozzle ring. The nozzle flow channel deflection surface is tapered, and the minimum throat area is achieved at the pre-swirl nozzle outlet.

[0014] Furthermore, the first-stage annular gap width b 1 Size range is 0.1~0.25mm, second level annular seam width b 2 The size range is 0.1~0.2mm, and the first-stage annular gap is located upstream of the airflow.

[0015] Furthermore, the total throat area of ​​the pre-swirl nozzle is ADetermined by the following formula, , In the formula, m is the gas supply mass flow rate; C d is the pre-swirl nozzle flow coefficient, C d The value range is 0.80~0.95; in , p out They 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 airflow at the pre-swirl nozzle inlet; k is the adiabatic index of the pre-swirl nozzle inlet airflow; R g is the gas constant, which is 287 J / (kg•K); The nozzle grid distance of the pre-swirl nozzle t Determined by the following formula, , Where A is the total throat area of ​​the pre-swirl nozzle; N is the number of pre-swirl nozzles; θ is the pre-spin angle; Nozzle pitch t The value range is 10mm~20mm, which determines the number of pre-swirl nozzles N The value of .

[0016] Furthermore, 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.

[0017] Compared with the prior art, the present invention has the following technical effects: a decompression throttling pre-swirl nozzle device for a pre-swirl air supply system, which reduces the intake pressure and flow rate of the pre-swirl air supply system through the setting of the pre-swirl nozzle, the nozzle outer ring grate teeth, the nozzle inner ring grate teeth and the decompression ring cavity, and does not change the shape and position of the pressure surface and suction surface of the pre-swirl nozzle, which will not have an adverse effect on the acceleration and flow performance of the pre-swirl nozzle, and maintains the good performance of the pre-swirl nozzle. The device has a simple structure, low processing difficulty, and convenient installation. It effectively reduces the intake pressure and flow rate of the pre-swirl air supply system, and can ensure the uniformity of the air supply while meeting the air supply volume requirements of the pre-swirl air supply system, thereby improving the overall performance and reliability of the aircraft engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a meridian cross-sectional view of the present invention; Figure 2 It is a schematic diagram of assembling the inner ring and the outer ring of the nozzle of the present invention; Figure 3 It is a schematic diagram of the structure of the inner ring of the nozzle of the present invention; Figure 4 It is a schematic diagram of the nozzle outer ring structure of the present invention; Figure 5 It is the velocity streamline diagram before the nozzle of the present invention; Figure 6 It is the velocity streamline diagram in the nozzle of the present invention. In the figure: 1. nozzle outer ring; 2. nozzle inner ring; 3. pre-swirl nozzle; 4. nozzle outer ring grate teeth; 5. nozzle inner ring grate teeth; 6. pressure relief ring cavity; 7. first-stage annular gap; 8. second-stage annular gap; 9. flange. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below in conjunction with the accompanying drawings; the examples given are only used to explain the present invention; they are not used to limit the scope of the present invention.

[0020] In order to achieve the above object, the present invention provides the following specific implementation methods: Example 1: Figure 1 As shown, a decompression throttling pre-swirl nozzle device for a pre-swirl air supply system is characterized in that the pre-swirl nozzle 3 includes a nozzle outer ring 1 and a nozzle inner ring 2, and the nozzle outer ring grate teeth 4 and the nozzle inner ring grate teeth 5 are correspondingly arranged in the annular cavity between the nozzle outer ring 1 and the nozzle inner ring 2, and the nozzle outer ring grate teeth 4 and the nozzle inner ring grate teeth 5 form a decompression annular cavity 6. The airflow enters the decompression annular cavity to form a vortex, which reduces the intake pressure and also increases the flow resistance, thereby achieving a throttling effect.

[0021] A flange 9 is also provided on the nozzle outer ring 1, and a first-level annular gap 7 is formed between the nozzle outer ring grate teeth 4 and the nozzle inner ring 2, and a second-level annular gap 8 is formed between the nozzle inner ring grate teeth 5 and the nozzle outer ring grate teeth 4. After the airflow passes through the first-level annular gap 7, the pressure and flow rate are reduced, and then the airflow enters the pressure reducing annular cavity, where a vortex is formed to increase the flow resistance and achieve the throttling effect. Then, the pressure and flow rate are reduced again through the second-level annular gap 8, so that the airflow flow rate and pressure finally meet the air supply requirements and ensure the uniformity of the air supply.

[0022] The nozzle inner ring 2 and the nozzle outer ring 1 are assembled with interference fit, and the interference amount is 0.05mm~0.15mm.

[0023] The nozzle inner ring 2 and the nozzle inner ring grate teeth 5 adopt an integrated structure, the flange 9, the nozzle outer ring 1 and the nozzle outer ring grate teeth 4 adopt an integrated structure, and the flange 9 is connected and fixed to the engine casing support ring.

[0024] Nozzle outer ring grate teeth 4 tilt angles δ1 range is 33°~45°, height H 1 Size range is 6.5mm~7.0mm, nozzle inner ring grate teeth 5 tilt angle δ 2Range: 35°~57°, height H 2 The size range is 4.5mm~5mm; the nozzle outer ring grate teeth 4 and the nozzle inner ring grate teeth 5 are both inclined toward the direction of the incoming air flow.

[0025] Pre-swirl deflection angle of pre-swirl nozzle 3 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 3 is consistent with the rotation direction of the turbine disk. The pre-swirl nozzle 3 uses the blade pressure surface and the blade suction surface to form an inclined hole flow channel with equal intervals and circumferential deflection on the nozzle ring. The nozzle flow channel deflection surface is tapered, and the minimum throat area is achieved at the pre-swirl nozzle outlet.

[0026] Width of first level annular gap 7 b 1 Size range is 0.1~0.25mm, second level annular seam 8 width b 2 The size range is 0.1~0.2mm, and the first-stage annular gap 7 is located upstream of the airflow.

[0027] Total throat area of ​​pre-swirl nozzle 3 A Determined by the following formula, , In the formula, m is the gas supply mass flow rate; C d is the pre-swirl nozzle flow coefficient, C d The value range is 0.80~0.95; in , p out They 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 airflow at the pre-swirl nozzle inlet; k is the adiabatic index of the pre-swirl nozzle inlet airflow; R g is the gas constant, which is 287 J / (kg•K); like Figure 3 As shown, the nozzle pitch of the pre-swirl nozzle 3 t Determined by the following formula, , Where A is the total throat area of ​​the pre-swirl nozzle; N is the number of pre-swirl nozzles; θ is the pre-spin angle; Nozzle pitch tThe value range is 10mm~20mm, which determines the number of pre-swirl nozzles N The value of .

[0028] The nozzle blade height h of the pre-swirl nozzle 3 is determined by the following formula: , The nozzle blade height h ranges from 5mm to 10mm.

[0029] In the specific implementation, taking the leaf hole pre-swirl nozzle as an example, the pre-swirl angle is 15°. The pre-swirl nozzle is designed according to 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 small air supply flow rate, among which the inlet air flow adiabatic index is k It is 1.3443.

[0030] Table 1 Boundary conditions of pre-swirl air supply system

[0031] The traditional leaf hole pre-swirl nozzle is selected for design. The total throat area A, nozzle grid distance t, and nozzle leaf height h of the pre-swirl nozzle can be calculated by the formula, where the pre-swirl nozzle flow coefficient C d Take 0.935.

[0032] Table 2 shows two design schemes with different numbers of pre-swirl nozzles. It can be seen from Table 2 that in the design scheme with 24 nozzles, the nozzle height is only 2.58mm and the nozzle grid pitch t is 5.16mm. The size is too small, making processing difficult and the processing cost high. In the design scheme with 4 nozzles, although the nozzle height and grid pitch are within a reasonable range, the number of nozzles is too small, which will cause the problem of uneven air supply, thereby reducing the sealing effect of the wheel rim and increasing the risk of gas intrusion.

[0033] Table 2 Design scheme of traditional pre-swirl nozzle

[0034] If the decompression throttling pre-swirl nozzle device of the present invention is selected for design, the device can reduce the total pressure of the nozzle inlet p *in is reduced to 333.5kpa, nozzle flow coefficient C d Reduced to 0.80.

[0035] Table 3 shows the design results. It can be seen that compared with the traditional blade hole pre-swirl nozzle design, the present invention can increase the total throat area, nozzle height and nozzle pitch of the pre-swirl nozzle to a reasonable range, which is conducive to processing and installation. At the same time, it can also increase the number of nozzles to ensure the uniformity of air supply.

[0036] Table 3 Selected design solutions of the present invention

[0037] The boundary conditions of the pre-swirl air supply system are given according to the data in Table 1, and the pre-swirl air supply system is designed according to the geometric structure parameters in Table 3. The CFD numerical simulation of the pressure reducing throttling pre-swirl nozzle device of the present invention is carried out. The air supply flow rate meets the design requirements. At the same time, the following is obtained: Figure 1 The velocity streamlines before the pre-swirl nozzle and Figure 2 The velocity streamline diagram in the nozzle shown in the figure shows that obvious vortices are formed in the air pressure relief ring cavity and behind the grate teeth, which can achieve the effect of pressure relief and throttling. The air intake at the nozzle inlet is uniform, the air flow in the nozzle has no vortex, the flow loss is small, and the air flow at the nozzle outlet is also relatively uniform, with good air supply uniformity.

[0038] See also Figure 4~Figure 6 When processing the pre-spin nozzle disk, the nozzle inner ring 2 and the nozzle outer ring 1 are processed separately. There are 24 leaf hole pre-spin nozzles evenly distributed on the inner ring of the nozzle. The comb teeth of the inner ring of the nozzle are also processed integrally with the inner ring of the nozzle, and the comb teeth of the outer ring of the nozzle are processed integrally with the outer ring of the nozzle. During assembly, ensure that the inner ring of the nozzle and the outer ring of the nozzle have an interference fit of 0.1mm in diameter, and use the outer ring heating method for assembly to nest the outer ring of the nozzle on the inner ring of the nozzle.

[0039] The decompression throttling pre-swirl nozzle device for the pre-swirl air supply system of the present invention is simple and convenient in processing and installation. The nozzle inner ring grate teeth 5 and the nozzle inner ring 2 are processed as a whole, and then the nozzle outer ring is processed, and the nozzle outer ring grate teeth and the nozzle outer ring are processed as a whole. During assembly, the nozzle outer ring is nested on the nozzle inner ring.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system, characterized in that: The pre-swirl nozzle comprises an outer nozzle ring and an inner nozzle ring, and the outer nozzle ring grate teeth and the inner nozzle ring grate teeth are correspondingly arranged in the annular cavity between the outer nozzle ring and the inner nozzle ring, and the outer nozzle ring grate teeth and the inner nozzle ring grate teeth form a decompression annular cavity.

2. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 1, characterized in that: A flange is also provided on the outer ring of the nozzle, and a first-level annular gap is formed between the comb teeth of the outer ring of the nozzle and the inner ring of the nozzle, and a second-level annular gap is formed between the comb teeth of the inner ring of the nozzle and the comb teeth of the outer ring of the nozzle. After the airflow passes through the first-level annular gap, the pressure and flow rate are reduced, and then it enters the pressure reduction ring cavity, where a vortex is formed, which increases the flow resistance and achieves the throttling effect. After passing through the second-level annular gap, the pressure and flow rate are reduced again.

3. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 1 or 2, characterized in that: The nozzle inner ring and the nozzle inner ring comb teeth adopt an integrated structure, the flange, the nozzle outer ring and the nozzle outer ring comb teeth adopt an integrated structure, and the flange is connected and fixed to the engine casing support ring.

4. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 3, characterized in that: The inner ring and the outer ring of the nozzle are assembled by interference fit, and the interference fit amount is 0.05mm-0.15mm.

5. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 3, characterized in that: The inclination angle of the outer ring grate teeth of the nozzle δ 1 range is 33°~45°, height H 1. The size range is 6.5mm~7.0mm, and the inclination angle of the inner ring grate of the nozzle is δ 2Range: 35°~57°, height H 2 The size range is 4.5mm~5mm; the outer ring grate teeth of the nozzle and the inner ring grate teeth of the nozzle are inclined toward the direction of the incoming air flow.

6. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 1, characterized in that: The pre-swirl deflection angle of the pre-swirl 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 hole flow channel with equal intervals and circumferential deflection along the nozzle ring. The nozzle flow channel deflection surface is tapered, and the minimum throat area is achieved at the pre-swirl nozzle outlet.

7. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 2, characterized in that: The first-stage annular gap width b 1 Size range is 0.1~0.25mm, second level annular seam width b 2 The size range is 0.1~0.2mm, and the first-stage annular gap is located upstream of the airflow.

8. A decompression throttling pre-swirl nozzle device for a pre-swirl air supply system as claimed in claim 6, characterized in that: The total throat area of ​​the pre-swirl nozzle A Determined by the following formula, ， In the formula, m is the gas supply mass flow rate; C d is the pre-swirl nozzle flow coefficient, C d The value range is 0.80~0.95; in , p out They 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 airflow at the pre-swirl nozzle inlet; k is the adiabatic index of the pre-swirl nozzle inlet airflow; R g is the gas constant, which is 287 J / (kg•K); The nozzle grid distance of the pre-swirl nozzle t Determined by the following formula, ， Where A is the total throat area of ​​the pre-swirl nozzle; N is the number of pre-swirl nozzles; θ is the pre-spin angle; Nozzle pitch t The value range is 10mm~20mm, which determines the number of pre-swirl nozzles N The value of the pre-swirl nozzle nozzle blade height h is determined by the following formula, ， The nozzle blade height h ranges from 5mm to 10mm.

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