Porous annular rib structure applied to dedusting characteristic of aero-engine air system

Abstract

The invention provides a porous annular rib structure applied to the dust removal characteristic of an aero-engine air system, and belongs to the technical field of aero-engine air system dust removal. In order to improve the clean degree of cold air flow of an aero-engine, keep pressure loss within an acceptable range, maximally reduce the particle volume fraction of the air flow reaching the turbine blade, reduce the deposition rate of particles in a cold channel in the turbine blade, and further improve the service life and the stability of the turbine blade. The porous annular rib plate is arranged in the pre-whirling air inlet cavity, in addition, the turbulent flow ribs are arranged on the downstream portion of the porous annular rib plate, particles can collide with the wall faces of the turbulent flow ribs, the kinetic energy of the particles is reduced, finally part of the particles can be deposited on the surfaces of the turbulent flow ribs, separation of the particles and cooling airflow is achieved, and the cleaned cooling airflow finally flows to the pre-whirling nozzle. Due to the hindering effect of the porous annular rib plate and the turbulent flow ribs, part of particles are deposited in the pre-swirling air inlet cavity, and cleaning of an aero-engine air system is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of dust removal of aircraft engine air systems, and in particular relates to a porous annular rib structure applied to dust removal characteristics of aircraft engine air systems. Background Art

[0002] Aircraft engines operating in strong dusty environments are accompanied by high concentrations of fine dust particles. Even after passing through the inlet particle separator, small dust particles still enter the engine, traveling with the air flow. These dust particles, in addition to being impacted by the main flow of air onto the blade surfaces, causing abrasion and deposition, also travel through the air system into the turbine rotor cooling system, where they rapidly erode the pre-swirl nozzle assembly, accumulate in the turbine disc cavity, and deposit and clog the turbine blade cooling channels. These effects can have a significant negative impact on the engine's service life, performance, and safe operation.

[0003] Turbine structures are widely used in the design of internal structures of aircraft engines. Different distribution patterns of spoiler ribs can induce a variety of complex flow phenomena, such as vortexes, secondary flows, and flow reattachment, which can change the transport and deposition characteristics of particles inside the engine and achieve the separation of dust particles from the incoming flow. In a typical aircraft engine turbine disc cavity structure, the sand-laden cooling air introduced from the front of the compressor enters the pre-swirl inlet cavity through the air inlet hole, and then passes through the pressure reduction and acceleration of the pre-swirl nozzle, and enters the rotor blades through the air inlet hole to cool the turbine blades. Compared with the disc cavity structure, the inner cavity of the rotor blade is complex and narrow, and the problem of sand and dust particle deposition and blockage in its internal cooling channels and film holes is more prominent, and the problem of reduced life caused by cooling failure of the turbine rotor blades is more serious.

[0004] Therefore, the turbulent structure can be used to change the distribution characteristics of the cooling air flow field, promote the deposition of sand and dust particles in the pre-swirl inlet cavity, reduce the sand and dust content entering the internal flow channel entrance of the turbine blade, and effectively reduce the amount of sand and dust deposition in the rotor blade cavity and the risk of deposition blockage. The sand and dust particles accumulated in the pre-swirl disc cavity can eventually be discharged through the sand discharge holes. The filter plate utilizes the difference between the gas and solid phases. When the particle-laden airflow passes through the filter porous plate, the gas can pass normally, and the solid particles are intercepted and deposited on the surface of the plate due to the array distribution structure on the plate surface.

[0005] The main focus of the existing technical methods is to arrange spoiler structures in the winding channels inside the turbine blades to reduce the deposition rate of particles. Although this method can reduce the particle deposition rate, due to the small size of the winding channels inside the turbine blades, there are certain limitations in the arrangement of spoiler ribs. Compared with aircraft engine components, under the same deposition amount, the performance of turbine blades is more significantly affected by the negative impact of particle deposition, and is more prone to problems such as blockage and ablation. This implementation focuses on the upstream components of the turbine blades, and arranges annular porous filter ribs and annular spoiler ribs in the pre-swirl inlet cavity. While minimizing the pressure loss caused by the structure itself, it maximizes the separation of particles and incoming flow, allowing cleaner airflow to pass through the pre-swirl nozzle and enter the turbine blades, which is of great significance for the stable operation of the turbine blades. Summary of the Invention

[0006] In view of this, in order to improve the cleanliness of aircraft engine cooling airflow, maintain pressure loss within an acceptable range, minimize the volume fraction of particles in the airflow reaching the turbine blades, reduce the particle deposition rate in the cooling channels within the turbine blades, and further improve the life and stability of the turbine blades, the present invention proposes a porous annular rib structure for dust removal in aircraft engine air systems. Specifically, a porous annular rib is arranged within the pre-swirl intake cavity. The cooling airflow forms a recirculation zone on the upstream and downstream sides of the porous annular rib, increasing the particle impact rate and reducing the particle kinetic energy, ultimately causing the particles to deposit on the surface of the porous annular rib. In addition, a spoiler rib is arranged downstream of the porous annular rib. Particles collide with the rib wall, reducing their kinetic energy. Eventually, some particles will deposit on the rib surface, separating the particles from the cooling airflow. The cleaned cooling airflow ultimately flows to the pre-swirl nozzle. Due to the obstruction of the porous annular rib and the spoiler rib, some particles are deposited in the pre-swirl intake cavity, achieving cleanliness of the aircraft engine air system. At the same time, the array hole structure of the porous annular rib ensures that the fluid will not generate excessive pressure loss after flowing through the porous annular rib.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a porous annular rib structure applied to the dust removal characteristics of an aircraft engine air system, comprising an air collecting chamber, an air inlet hole, a pre-swirl air inlet chamber, a porous annular rib plate and annular spoiler ribs. The air collecting chamber is connected to the pre-swirl air inlet chamber through the air inlet hole. The porous annular rib plate and the annular spoiler ribs are arranged in sequence in the pre-swirl air inlet chamber. After the cooling airflow passes through the porous annular rib plate, the orifice plate structure will intercept the particles entering the pre-swirl air inlet chamber for the first time, and some particles will be deposited on the surface of the orifice plate. Then the cooling airflow flows through the annular spoiler ribs in turn, and the annular spoiler ribs will intercept the particles for a second time, and finally the cleaned cooling airflow enters the pre-swirl nozzle.

[0008] Furthermore, the porous annular rib is perpendicular to the impact target surface in the pre-swirl intake cavity.

[0009] Furthermore, the inner circle radius R1 of the porous annular rib is 185.1 mm, the outer circle radius R2 is 204.4 mm, and the rib height H1 is 0.1 mm.

[0010] Furthermore, the porous annular rib is evenly and equidistantly provided with a number of impact holes parallel to the normal direction of the orifice plate wall, and the impact holes are distributed along the radial direction.

[0011] Furthermore, the number of radial linear arrays of the impact holes is 20, the spacing a is 0.4~0.9 mm, the number of circumferential arrays is 534, the spacing b is 2.17~2.37 mm, the impact hole diameter d is 0.6~0.8 mm, and the porosity of the porous annular rib is 12.78%~22.73%.

[0012] Furthermore, the number n of the annular spoiler ribs is 1 to 3.

[0013] Furthermore, there are two annular spoiler ribs, which are respectively arranged on the impact target surface and the outer side surface in the pre-swirl intake cavity, and the cross-section of the annular spoiler ribs is rectangular.

[0014] Furthermore, the first annular spoiler rib is arranged 20 mm downstream of the stagnation point, with a rib height h1 of 5 mm, a rib width e1 of 2.5 mm, and a spoiler rib spacing of 0.5 to 2 mm.

[0015] Furthermore, taking the outer wall surface of the pre-swirl intake cavity as a reference surface, a second annular spoiler rib is arranged in a direction perpendicular to the outer wall surface, with a rib height h2 of 3.3 mm and a rib width e2 of 2 mm.

[0016] Compared with the prior art, the porous annular rib structure for dust removal in an aircraft engine air system according to the present invention has the following beneficial effects: The present invention firstly intercepts the particles in the cold air flow without causing excessive pressure loss by arranging porous annular ribs in the pre-swirl air intake chamber. The cold air flow will form a recirculation zone on the upstream and downstream sides of the porous annular ribs, which greatly increases the number of collisions between the particles and the wall, increases the momentum loss of the particles, reduces the particle movement speed, and is more likely to fall below the critical capture speed of the wall, and finally deposit on the surface of the porous orifice plate. At the same time, annular spoiler ribs are arranged on the impact target surface and the outer side surface to further intercept the particles, so that the particles are deposited on the annular rib surface, and then the cleaned cold air flow flows to the pre-swirl nozzle. Due to the obstruction of the porous annular ribs and the spoiler ribs, some particles are deposited in the pre-swirl air intake chamber, thereby achieving the cleaning of the aircraft engine air system. At the same time, the array hole structure of the porous annular ribs ensures that the fluid will not generate excessive pressure loss after flowing through the porous annular ribs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 A schematic diagram of the partial structure of a typical turbine disc cavity of an aero-engine with a pre-swirl inlet cavity according to the present invention; Figure 2 A schematic diagram of a porous annular rib dust accumulation structure for use in a pre-swirl intake cavity of an aircraft engine turbine according to the present invention; Figure 3 The present invention provides a three-dimensional layout of a porous annular rib structure and annular spoiler columns for dust removal in an aero-engine air system; Figure 4 A schematic diagram of a two-dimensional layout of a porous annular rib plate of a porous annular rib structure for dust removal in an aero-engine air system according to the present invention; Figure 5 is the streamline distribution characteristics of the typical turbine disc cavity; Figure 6 The streamline distribution characteristics in the disc cavity of the structure of the present invention; Figure 7 The particle motion trajectory characteristics of a porous annular rib structure used in the dust removal characteristics of an aircraft engine air system of the present invention; Figure 8 The particle motion trajectory characteristics of a typical turbine disc cavity structure; Figure 9 The particle deposition rate of a typical turbine structure and the porous annular rib structure of the present invention is applied to the dust removal characteristics of an aircraft engine air system.

[0018] In the figure: 1-air collecting chamber, 2-air inlet, 3-rotor-stator chamber, 4-pre-swirl nozzle, 5-No. 1 annular spoiler rib, 6-No. 2 annular spoiler rib, 7-porous annular rib. DETAILED DESCRIPTION

[0019] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0020] See also Figure 1-9 This embodiment describes a porous annular rib structure for dust removal in an aircraft engine air system, which is applied to the pre-swirl inlet cavity area at the front end of the pre-swirl nozzle of the aircraft engine. Figure 1-2Only 1 / 6 of the original model is shown. The actual entire structure is a full circle. The porous annular rib structure consists of an air collecting chamber 1, an air inlet 2, a pre-swirl air inlet chamber 3, a porous annular rib 4 and annular spoiler ribs. A porous annular rib 4 and two annular spoiler ribs are arranged in the pre-swirl air inlet chamber 3. After the cooling airflow passes through the porous annular rib 4, the orifice plate structure will intercept the particles entering the pre-swirl air inlet chamber 3 for the first time. The particles will break away from the airflow and collide on the surface of the porous annular rib 4. The movement speed of the particles will decrease, and some particles will be deposited on the surface of the orifice plate. The porous annular rib 4 will not cause excessive pressure loss while blocking the particles. The cooling airflow then flows through the annular spoiler rib, which will intercept the particles for a second time. Finally, the cleaned cooling airflow enters the pre-swirl nozzle 7.

[0021] The porous annular rib 4 is arranged within the pre-swirl intake chamber 3, perpendicular to the impact target surface within the pre-swirl intake chamber 3. The inner ring radius R1 of the porous annular rib 4 is 185.1 mm, the outer ring radius R2 is 204.4 mm, and the rib height H1 is 0.1 mm. The plate is evenly and equidistantly provided with a number of impact holes parallel to the normal direction of the orifice plate wall. The impact holes are distributed along the radial direction. The number of radial linear arrays is 20, with a spacing a of 0.4 to 0.9 mm. The number of circumferential arrays is 534, with a spacing b of 2.17 to 2.37 mm. The impact hole diameter d is 0.6 to 0.8 mm, and the porosity of the porous annular rib is 12.78% to 22.73%.

[0022] Two annular spoiler ribs are placed on the impact target surface and outer side surface of the pre-swirl inlet cavity 3. The spoiler ribs have a rectangular cross-section. The stagnation point at the intersection of the impact hole axis and the impact target surface is used as the reference point, and the surface on which the stagnation point lies is used as the reference surface. A reference line is established through the stagnation point, the reference surface, and perpendicular to the reference surface. The annular rib is placed downstream of the stagnation point. A stator cavity without annular spoiler ribs is used as the reference model.

[0023] The number n of annular spoiler ribs is 1 to 3, and preferably 2 in the present invention. Increasing the number and height of the ribs is intended to improve the deposition rate within the disc cavity, but excessively high ribs increase flow loss. The present invention designs two annular spoiler ribs, which increase the deposition rate while minimizing pressure loss using two ribs of relatively low height.

[0024] The first annular spoiler rib 5 of the present invention is positioned 20 mm downstream of the stagnation point, with a rib height h1 of 5 mm, a rib width e1 of 2.5 mm, and a rib spacing of 0.5 to 2 mm. Using the outer wall of the pre-swirl inlet cavity 3 as a reference surface, the second annular spoiler rib 6 is positioned perpendicular to the outer wall, with a rib height h2 of 3.3 mm and a rib width e2 of 2 mm.

[0025] In this embodiment, the cooling airflow carrying particles flows from the air collecting chamber 1 through the air inlet 2 to the pre-swirl air inlet chamber 3. The cooling airflow passes through the porous annular rib 4. In the process of flowing out from the porous structure, the particles collide with the wall. The kinetic energy of the particles decreases, and some particles will be deposited on the surface of the porous annular rib 4. Then the fluid is distributed along the impact target. The No. 1 annular spoiler rib 5 and the No. 2 annular spoiler rib 6 strengthen the disturbance and obstruction of the airflow. The particles further collide with the No. 1 annular spoiler rib 5 and the No. 2 annular spoiler rib 6, and the energy loss of the particles increases. The movement speed of the particles is easily lower than the critical capture speed of the wall, causing the particles to be deposited and the clean cooling airflow flows to the pre-swirl nozzle.

[0026] Compared with the original model, the model described in this embodiment can improve the particle deposition rate in the particle size range of 1um~20um. In the particle size range of 1um~10um, as the particle size increases, the particle flowability becomes worse, but its initial kinetic energy entering the disc cavity from the connecting hole increases. Although after multiple collisions, the energy loss ratio is low, it still has not reached the deposition state. In the particle size range of 10um~20um, as the particle size increases, the particle deposition rate described in this embodiment increases, and the deposition rate of the original structure does not change significantly. In particular, when the particle size is 20um, the particle deposition rate described in this embodiment is most significantly improved. As the particle size continues to increase, the mass of the particles under the same density conditions increases, and the collision effect when flowing through the porous annular structure is more obvious. The larger initial particle velocity makes the rebound effect after the particles collide with the wall more intense, and the number of collisions between the particles and the wall increases significantly, causing the particles to lose more kinetic energy and eventually deposit on the wall. The embodiments of the present invention disclosed above are intended only to illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A porous annular rib structure for dust removal in an aircraft engine air system, characterized by: The invention comprises an air collecting chamber (1), an air inlet hole (2), a pre-swirl air inlet chamber (3), a porous annular rib plate (4) and an annular spoiler rib, wherein the air collecting chamber (1) is connected to the pre-swirl air inlet chamber (3) through the air inlet hole (2), and the porous annular rib plate (4) and the annular spoiler rib are arranged in sequence in the pre-swirl air inlet chamber (3). After the cooling airflow passes through the porous annular rib plate (4), the orifice plate structure intercepts the particles entering the pre-swirl air inlet chamber (3) for the first time, and some particles are deposited on the surface of the orifice plate. Then, the cooling airflow flows through the annular spoiler ribs in sequence, and the annular spoiler ribs intercept the particles for the second time, and finally the cleaned cooling airflow enters the pre-swirl nozzle (7).

2. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 1, characterized in that: The porous annular rib (4) impacts the target surface perpendicularly to the pre-swirl air inlet cavity (3).

3. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 1, characterized in that: The inner circle radius R1 of the porous annular rib (4) is 185.1 mm, the outer circle radius R2 is 204.4 mm, and the rib height H1 is 0.1 mm.

4. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 1, characterized in that: The porous annular rib (4) is evenly and equidistantly provided with a number of impact holes parallel to the normal direction of the orifice plate wall, and the impact holes are distributed along the radial direction.

5. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 4, characterized in that: The number of radial linear arrays of the impact holes is 20, the spacing a is 0.4-0.9 mm, the number of circumferential arrays is 534, the spacing b is 2.17-2.37 mm, the impact hole diameter d is 0.6-0.8 mm, and the porosity of the porous annular rib is 12.78%-22.73%.

6. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 1, characterized in that: The number n of annular spoiler ribs is 1 to 3.

7. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 6, characterized in that: There are two annular spoiler ribs, which are respectively arranged on the impact target surface and the outer side surface in the pre-swirl air inlet cavity (3), and the cross-sectional shape of the annular spoiler ribs is rectangular.

8. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 7, characterized in that: The first annular spoiler rib (5) of the two annular spoiler ribs is arranged 20 mm downstream of the stagnation point, with a rib height h1 of 5 mm, a rib width e1 of 2.5 mm, and a spoiler rib spacing of 0.5 to 2 mm.

9. The porous annular rib structure for dust removal in an aircraft engine air system according to claim 8, characterized in that: Taking the outer wall surface of the pre-swirl air inlet cavity (3) as a reference surface, a second annular spoiler rib (6) is arranged in a direction perpendicular to the outer wall surface, with a rib height h2 of 3.3 mm and a rib width e2 of 2 mm.

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