A centrifugal impeller back cavity rotational flow control assembly adaptive to engine state changes

Abstract

The present application relates to the technical field of aero-engine, and solves the problems that the direction of the axial force of the high-pressure rotor is backward in the light load and reverse state of the current engine, and the axial force of the high-pressure rotor is too large to exceed the allowable load of the bearing in the large state of the engine, in particular to a centrifugal impeller back cavity rotational flow control assembly which is self-adaptive to the state change of the engine, comprising a centrifugal impeller, a radial expansion casing is arranged outside the centrifugal impeller, an inner casing is fixedly connected to the bottom of the radial expansion casing, and a bleed air adjusting mechanism is arranged on the back cavity side of the centrifugal impeller. The present application realizes the self-adaptive switching of the bleed air of the back cavity of the centrifugal impeller from the low speed state such as the idle state to the high speed state by utilizing the difference between the alloy thermal expansion deformation performance of the flow guide partition plate and the radial expansion casing, the inner space of the inner bleed air channel can be heat exchanged with the external air through the through hole on the flow guide partition plate, and the local temperature of the parts of the engine is prevented from being too high when the high speed is pushed up.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and in particular to a centrifugal impeller back cavity swirl control assembly that adapts to changes in engine conditions. Background Technology

[0002] For small and medium-sized aero engines that use centrifugal compressors, the impeller back cavity often adopts a radial inward flow induced airflow form. For high pressure ratio engines with a pressure ratio greater than 20, the absolute pressure of the centrifugal impeller back cavity is large, and the back cavity swirl coefficient value has a great influence on the cavity pressure, which in turn affects the axial force of the entire rotor.

[0003] The axial force generated in the centrifugal impeller back cavity is caused by the high-pressure air drawn from the root of the centrifugal impeller outlet acting directly on the rotating side of the back cavity, generating a forward axial force in the horizontal direction. The centrifugal impeller itself also has a large backward aerodynamic axial force. The axial force in the centrifugal impeller back cavity plays an important role in balancing the aerodynamic force of the centrifugal impeller. The difference between the axial force in the centrifugal impeller back cavity and the aerodynamic force of the centrifugal impeller accounts for a large proportion in the calculation and modeling of the engine axial force.

[0004] Because centrifugal compressors have low pressure ratios at low speeds, the difference in axial force between the impeller back cavity and the centrifugal impeller after balancing is very small. This results in a light load and reverse-direction problem in the rearward direction at low speeds. At high speeds, although the centrifugal impeller can achieve the expected design pressure ratio, the difference in axial force between the impeller back cavity and the centrifugal impeller after balancing may be too large, leading to excessive axial force on the forward-direction rotor of the engine, which may even exceed the allowable load of the bearing. Existing conventional impeller back cavity bleed air technology cannot achieve adaptive cavity pressure and axial force adjustment functions according to changes in engine conditions. Therefore, it is essential to design a centrifugal impeller back cavity swirl control component that adapts to changes in engine conditions to achieve adaptive adjustment of the centrifugal impeller back cavity pressure according to changes in engine conditions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a centrifugal impeller back cavity swirl control component that adapts to changes in engine state. The purpose is to enable the automatic adjustment of the bleed air state of the centrifugal impeller back cavity according to changes in the magnitude of engine output power. This solves the problems of light load and reverse axial force of the high-pressure rotor when the engine is in a slow, low-load state, and excessive forward axial force of the high-pressure rotor when the engine is in a high-load state, exceeding the allowable load of the bearing.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a centrifugal impeller back cavity swirl control assembly for adaptive engine state changes, comprising a centrifugal impeller, a radial expansion casing provided on the outer side of the centrifugal impeller, an inner casing fixedly connected to the bottom of the radial expansion casing, an air bleed adjustment mechanism provided on the back cavity side of the centrifugal impeller, the air bleed adjustment mechanism including a flow guide baffle, a sealing device provided on the flow guide baffle, and a ring of through holes opened at the bottom of the flow guide baffle, wherein the linear expansion coefficient of the material used for the flow guide baffle is greater than the linear expansion coefficient of the material used for the radial expansion casing.

[0007] The bottom of the radial expansion casing is bolted, and the radial expansion casing is fixedly connected to the inner casing by bolts. An O-ring is installed on the top of the flow guide baffle.

[0008] A 0.45mm cold gap is left between the O-ring seal and the inner wall of the radial expansion chamber cavity.

[0009] The flow guide baffle is fixedly connected to the radial expansion casing and the inner casing at one end facing the inner casing by bolts.

[0010] One side of the flow guide baffle forms an inner air intake channel with the inner wall of the radial expansion casing cavity, and the other side of the flow guide baffle forms an outer air intake channel with the back cavity side of the centrifugal impeller.

[0011] A throttling grate is fixedly installed at the bottom of the inner casing, with the bottom ends of the throttling grate facing the external air intake channel.

[0012] The connecting surface of the radial expansion casing facing the inner casing is inclined, and the inner diameter of the inner air intake channel gradually increases from top to bottom.

[0013] The through hole is located at the position of minimum radius of curvature of the flow guide baffle and is arranged circumferentially.

[0014] The axial distance between the flow guide baffle and the rotating side of the centrifugal impeller back cavity is 3-5 mm.

[0015] The outer diameter of the flow guide baffle is the same as the radius of the centrifugal impeller outlet root, and the inner diameter of the flow guide baffle is approximately 50% to 70% of the outer diameter.

[0016] Compared with the prior art, the present invention provides a centrifugal impeller back cavity swirl control component that adapts to changes in engine state, and has the following beneficial effects:

[0017] 1. By utilizing the difference in thermal expansion and deformation properties between the alloys used in the guide baffle and the radial expansion casing, the adaptive switching of bleed air from the back cavity of the engine centrifugal impeller from low-speed states such as idle to high-speed states is achieved. At low speeds such as idle, a radial gap exists between the O-rings on the radial expansion casing and the guide baffle. The bleed air from the back cavity of the centrifugal impeller passes through this radial gap and then through the through-hole, forming a radial outflow on the rotating side of the centrifugal impeller back cavity. This increases the cavity pressure and the forward axial force of the engine rotor, solving the problem of light load and reverse axial force of the rotor at low speeds. When the engine speed is pushed up to the maximum, the temperature of the parts can reach 400℃. Due to the difference in thermal expansion properties between different alloys, the outer edge of the O-ring seal and the radial expansion casing form a seal. The radial clearance of the inner air bleed channel between the guide baffle and the radial expansion casing is closed. The air bleed in the back cavity of the centrifugal impeller forms a pure radial inward flow air bleed form along the outer air bleed channel. This can improve the swirl coefficient of the impeller back cavity, reduce the cavity pressure, and solve the problem of excessive forward axial force of the high-pressure rotor at high engine speed. In this way, the air bleed form of the centrifugal impeller back cavity can be automatically switched according to the engine speed.

[0018] 2. When the engine is at high speed, the axial distance between the baffle and the rotating side of the centrifugal impeller back cavity is controlled at 3-5mm, resulting in a narrow external air intake channel. Under the condition of consistent air intake flow, the radial internal flow velocity increases, and the Coriolis force accelerates the circumferential velocity of the air intake flow, reducing the wind resistance power consumption and air intake temperature rise of the centrifugal impeller back cavity, and increasing the radial pressure drop of the airflow in the centrifugal impeller back cavity. This effectively ensures the reduction of the forward rotor axial force of the engine at high speed, preventing the difference between the axial force and the centrifugal impeller aerodynamic force from being too large and exceeding the allowable load of the bearing.

[0019] 3. Because the bottom bending area of ​​the guide baffle with a small radius of curvature has a ring of through holes arranged around it, when the engine is at low speed, the through holes play a role in airflow. Some airflow can pass through the through holes into the external air intake channel and form radial outward flow, which reduces the swirling flow in the back cavity of the centrifugal impeller, increases the cavity pressure, and increases the forward axial force of the engine rotor. When the engine speed is increased, due to the seal between the outer edge of the O-ring seal and the radial expansion casing, the internal space of the internal air intake channel can exchange heat with the external air through the through holes, preventing the local temperature of the parts from becoming too high.

[0020] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the structure of a prior art centrifugal impeller assembly is shown;

[0023] Figure 2 A force analysis diagram of a prior art centrifugal impeller assembly is shown.

[0024] Figure 3 The diagram shows the Coriolis force analysis of radial internal airflow in the back cavity of a prior art centrifugal impeller;

[0025] Figure 4 The diagram shows the Coriolis force analysis of radial outflow ducting in the back cavity of a prior art centrifugal impeller;

[0026] Figure 5 A schematic diagram of a centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to an embodiment of the present invention is shown.

[0027] Figure 6 A detailed schematic diagram of an O-ring and a flow guide plate according to an embodiment of the present invention is shown;

[0028] Figure 7 A schematic diagram of the bleed air state of the centrifugal impeller back cavity in a low state according to an embodiment of the present invention is shown.

[0029] Figure 8 A schematic diagram of the bleed air state of the centrifugal impeller back cavity under the large state of the engine according to an embodiment of the present invention is shown;

[0030] Figure 9 A schematic diagram of radial deformation of the engine structure under maximum state according to an embodiment of the present invention is shown.

[0031] Figure 10 A locally enlarged schematic diagram of radial deformation of the engine structure under maximum state according to an embodiment of the present invention is shown.

[0032] Figure 11 The diagram shows the swirl coefficient distribution of the impeller back cavity under conventional radial inward flow bleed air in the idle state of a prior art engine.

[0033] Figure 12The diagram shows the impeller back cavity swirl coefficient distribution under conventional radial outflow bleed air in engine idle state according to an embodiment of the present invention;

[0034] Figure 13 The diagram shows the static pressure coefficient distribution of the impeller back cavity under conventional radial inward bleed air in the idle state of a prior art engine.

[0035] Figure 14 The diagram shows the distribution of the impeller back cavity static pressure coefficient under conventional radial outflow bleed air in the engine idle state according to an embodiment of the present invention.

[0036] In the diagram: 1. Centrifugal impeller; 2. Radial expander casing; 3. Inner casing; 4. Bolt; 5. Air intake adjustment mechanism; 51. O-ring seal; 52. Flow guide baffle; 5a. Through hole; 6a. Inner air intake channel; 6b. Outer air intake channel. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please refer to Figure 1 The existing conventional engine centrifugal impeller bleed air assembly consists of a centrifugal impeller, a radial expansion casing, and an inner casing as stator components. The radial expansion casing and the inner casing are connected circumferentially by evenly distributed bolts to transfer loads. The mounting surface of the inner diameter of the radial expansion casing is kept at a certain distance from the axial direction of the rotating side of the impeller back cavity to ensure that there is sufficient installation space for the bolts between the radial expansion casing and the inner casing.

[0039] Please refer to Figure 2 The high-pressure air drawn from the root of the centrifugal impeller outlet acts directly on the rotating side of the back cavity, generating a forward axial force in the horizontal direction. At the same time, the centrifugal impeller itself also has a large backward aerodynamic axial force. The axial force of the centrifugal impeller back cavity plays an important role in balancing the aerodynamic force of the centrifugal impeller. The difference between the axial force of the centrifugal impeller back cavity and the aerodynamic force of the centrifugal impeller accounts for a large proportion in the calculation and modeling of the engine axial force.

[0040] Please refer to Figure 3 According to the theory of Coriolis force in the rotating disk cavity: Where F represents the Coriolis force, and m is the mass of the particle. The velocity relative to the rotating reference point. Let ω represent the angular velocity of the rotating system. "×" indicates the vector product of two vectors. The direction of the Coriolis force F follows the right-hand rule. When the air intake in the impeller back cavity is radially inward, the Coriolis force accelerates the swirling flow in the impeller back cavity. The radial pressure drop in the impeller back cavity is large, and the average cavity pressure is small, which can reduce the forward axial force in the impeller back cavity. The smaller the axial distance between the impeller back cavity and the stationary axis, the more obvious the acceleration effect of the Coriolis force on the swirling flow in the impeller back cavity. At high speeds, the compressor pressure ratio increases, the absolute pressure of the centrifugal impeller is high, and the difference in axial force between the impeller back cavity and the centrifugal impeller after balance is too large, even exceeding the allowable load of the bearing.

[0041] Please refer to Figure 4 When the bleed air in the impeller back cavity flows radially outward, the Coriolis force weakens the swirling effect in the impeller back cavity, which can reduce the radial pressure drop in the impeller back cavity, increase the cavity pressure, and increase the forward axial force in the impeller back cavity. Therefore, in low-speed engine conditions, the forward axial force of the impeller is small, and there is a problem of light load and reverse direction of the rotor axial force. By adjusting the bleed air to flow radially outward, the difference between the axial force in the impeller back cavity and the aerodynamic force of the centrifugal impeller can be appropriately increased.

[0042] Please refer to Figure 6 The air intake regulating mechanism 5 includes a flow guide baffle 52, which is made of high expansion alloy material, and an O-ring seal 51 is installed on the top of the flow guide baffle 52.

[0043] Please refer to Figure 5An adaptive centrifugal impeller back cavity swirl control assembly for engine state changes includes a centrifugal impeller 1, a radial expansion casing 2 on the outer side of the centrifugal impeller 1, bolts 4 installed at the bottom of the radial expansion casing 2, and an inner casing 3 fixedly connected to the radial expansion casing 2 by bolts 4. The centrifugal impeller is a rotating component, while the radial expansion casing and the inner casing are stator components. The radial expansion casing 2 is made of a low-expansion alloy. An air bleed adjustment mechanism 5 is provided on the back cavity side of the centrifugal impeller 1, and a through hole 5a is formed at the bottom of a flow guide baffle 52. An O-ring seal 51 and the inner wall of the radial expansion casing 2 cavity have a cold-state gap of about 0.45 mm. The end of the flow guide baffle 52 facing the inner casing 3 is connected to the radial expansion casing 3 by bolts 4. The expansion casing 2 and the inner casing 3 are fixedly connected. One side of the guide baffle 52 forms an inner air intake channel 6a with the inner wall of the expansion casing 2, and the other side of the guide baffle 52 forms an outer air intake channel 6b with the back cavity side of the centrifugal impeller 1. When the engine is at low speed, the through hole 5a serves as a flow passage, and some airflow can pass through the through hole 5a into the outer air intake channel 6b and flow radially upwards to reduce the swirling flow in the back cavity of the centrifugal impeller 1, increase the cavity pressure, and increase the forward axial force of the engine rotor. When the engine speed increases, due to the seal between the outer edge of the O-ring 51 and the expansion casing 2, heat exchange can be carried out between the internal space of the inner air intake channel 6a and the external air through the through hole 5a. To prevent localized overheating of components, a throttling grate is fixedly installed at the bottom of the inner casing 3. The bottom ends of the throttling grate are positioned facing the outer air intake channel 6b. The airflow flows radially inward through the rotating side of the back cavity of the centrifugal impeller 1. At the bottom of the outer air intake channel 6b, the throttling grate is used for cooling of the downstream components. The connecting surface of the radial expansion casing 2 facing the inner casing 3 is inclined. The inner diameter of the inner air intake channel 6a gradually expands from top to bottom, ensuring sufficient installation space for the bolts 4 between the guide baffle 52, the radial expansion casing 2, and the inner casing 3. The through hole 5a is located at a position with a smaller radius of curvature of the guide baffle 52 and is circumferentially arranged. The guide baffle 52 and the radial expansion casing 2... The expansion coefficients of the materials differ significantly, with the expansion coefficient of the baffle 52 being greater than that of the radial expansion casing 2. As the engine speed increases, the component temperature rises accordingly. The radial gap between the baffle 52 and the radial expansion casing 2 is sealed, forming a radial inward flow induced airflow pattern in the impeller back cavity. The Coriolis force accelerates the circumferential velocity of the induced airflow, reducing the wind resistance power consumption and induced air temperature rise in the back cavity of the centrifugal impeller 1, and increasing the radial pressure drop of the airflow in the back cavity of the centrifugal impeller 1, preventing the difference between the axial force and the aerodynamic force of the centrifugal impeller 1 from being too large. The outer diameter of the baffle 52 is the same as the radius of the outlet root of the centrifugal impeller 1, and the inner diameter of the baffle 52 is approximately 50% to 70% of the outer diameter. Figure 3 With the marked rotation axis direction, the guide baffle 52 is projected from right to left, and the projection surface is in the shape of a ring. The inner diameter of the ring is about 50% to 70% of the outer diameter.

[0044] Please refer to Figure 7The diagram shows the airflow in the back cavity of the centrifugal impeller 1 when the engine is at low speed. There is a radial gap between the radial expansion casing 2 and the O-ring seal 51. The airflow in the back cavity of the centrifugal impeller 1 passes through this radial gap and then through the through hole 5a, forming a radial outflow on the rotating side of the back cavity of the centrifugal impeller 1. This increases the cavity pressure and the forward axial force of the engine rotor, thus solving the problem of light load and reverse axial force of the rotor at low speed.

[0045] Please refer to Figure 8 The diagram shows the airflow in the back cavity of the centrifugal impeller 1 when the engine is at high speed. When the engine is at high speed, the temperature of the parts reaches 400℃. Due to the thermal expansion mechanism of the alloy, the guide baffle 52 expands further, which closes the cold gap between the outer edge of the O-ring 51 at the top of the guide baffle 52 and the radial expansion casing 2. The radial gap of the inner air duct 6a between the guide baffle 52 and the radial expansion casing 2 is closed. The airflow in the back cavity of the centrifugal impeller 1 forms a single radial inward flow along the outer air duct 6b, which can improve the swirl coefficient of the impeller back cavity, reduce the cavity pressure, and solve the problem of excessive forward axial force of the high-pressure rotor at high speed.

[0046] Table 1: Linear Expansion Coefficient of GH696

[0047]

[0048] Please refer to Table 1, which shows a schematic diagram of the linear expansion coefficient of GH696 disclosed in Volume 2 of the "China Aviation Materials Handbook". In the finite element calculation and analysis of this invention, the flow guide baffle 52 is made of GH696 material with a high expansion coefficient, and a comparative analysis is conducted.

[0049] Table 2: Linear Expansion Coefficient of GH903

[0050]

[0051] Please refer to Table 2, which shows a schematic diagram of the linear expansion coefficient of GH903 published in Volume 2 of the "China Aviation Materials Handbook". In the finite element calculation and analysis of this invention, the radial expansion casing 2 is made of GH696 material with a low expansion coefficient.

[0052] Please refer to Figure 9 The diagram shows an analysis with radial deformation data as the vertical axis. Through finite element calculation, it is found that when the engine is at high speed, the radial deformation of the radial expansion casing 2 is 0.51 mm and the radial deformation of the flow guide baffle 52 is 1.1 mm. The radial deformation of the flow guide baffle 52 is greater than that of the radial expansion casing 2.

[0053] Please refer to Figure 10 This shows a locally enlarged schematic diagram of the radial deformation of the structure under high engine speed conditions, based on finite element analysis.

[0054] Table 3: Finite Element Deformation Calculation Results

[0055] Location Material radius mm Radial deformation at 400℃ (mm) radial expansion casing GH903 210 0.51 baffle GH696 209.55 1.1 gap difference 0.45 －0.59

[0056] Please refer to Table 3, which shows the finite element deformation analysis diagrams of the radial expansion casing 2 and the flow guide baffle 52 at 400℃. The initial cold radial clearance between the radial expansion casing 2 and the flow guide baffle 52 is 0.45mm. Figure 9 After obtaining the radial deformation data of the radial expansion casing 2 and the flow guide baffle 52 in the finite element analysis, it was found that the radial clearance difference between the two was reduced by 0.59 mm compared with the cold state condition. Under the maximum state of the engine, the radial gap between the radial expansion casing 2 and the O-ring 51 on the flow guide baffle 52 can reach the state of interference seal, thereby realizing the switching of the bleed air in the back cavity of the centrifugal impeller 1 from radial outward flow to radial inward flow.

[0057] Table 4: Axial force results in the impeller back cavity (kgf, positive direction is backward)

[0058]

[0059] Please refer to Table 4, which shows a comparative analysis of the axial force in the back cavity of the centrifugal impeller 1 of the present invention and the existing conventional technical solutions. Conventional impeller back cavity bleed air technology solutions can only be either radial inward bleed air or radial outward bleed air. Using the technical solution of the present invention, the engine uses the radial outward bleed air solution under low speed conditions such as ground slowness. Under this condition, the axial force of the high-pressure rotor can be increased by 116 kgf compared with the conventional radial inward bleed air. This has a significant effect on solving the problem of light load and reverse axial force of rotor in engines with centrifugal impeller structure under low speed conditions such as ground slowness. When the engine speed is pushed to the maximum, due to the radial expansion deformation difference between the radial expansion casing 2 and the guide baffle 52, the system switches to the radial inward bleed air form, which can reduce the axial force of the engine rotor by 937 kgf, thus solving the problem of excessive axial force of the high-pressure rotor at high speed.

[0060] Figure 11 The figure shows the distribution of swirl coefficients at various locations in the impeller back cavity under conventional radial inward bleed air conditions in the idle state of an existing engine. In the figure, K represents the swirl coefficient.

[0061] Figure 12 The figure shows the distribution of swirl coefficients at various positions in the impeller back cavity in the idle state of the engine according to an embodiment of the present invention, where there is a radial clearance between the radial expansion casing and the guide baffle, and the impeller back cavity forms a radial outward air induced flow. In the figure, K represents the swirl coefficient.

[0062] By comparison Figure 11 and Figure 12Compared with conventional technical solutions, the centrifugal impeller back cavity swirl control technology component using this technical solution has a lower swirl coefficient in the back cavity of centrifugal impeller 1 when the engine is at idle, resulting in a larger forward axial force.

[0063] In addition, through Figure 11 and Figure 12 The comparison demonstrates the difference in swirl coefficient and radial pressure drop between the radially outward and radially inward induced airflow in the impeller back cavity, which corresponds to the axial force data in the impeller back cavity shown in Table 4. (Data results corresponding to Table 4)

[0064] Figure 13 The figure shows the static pressure coefficient distribution at various locations in the impeller back cavity under conventional radial inward bleed air configuration when the engine is in idle state. In the figure, Cp represents the static pressure coefficient.

[0065] Figure 14 The diagram shows the static pressure coefficient distribution at various locations in the impeller back cavity under conventional radial outflow bleed configuration when the engine is in idle state according to an embodiment of the present invention. In the diagram, Cp represents the static pressure coefficient.

[0066] By comparison Figure 13 and Figure 14 Compared to conventional technical solutions, the static pressure coefficient of the centrifugal impeller back cavity swirling control technology component using this technical solution is larger when the engine is at idle. This further illustrates that by adopting this technical solution, the problem of light load and reverse axial force of the rotor in an engine with a centrifugal impeller structure under low conditions such as ground slowness can be effectively solved.

[0067] This invention, through finite element analysis, confirms that by adopting this technical solution and optimizing the structural design, it utilizes the difference in linear expansion coefficients between the radial expansion casing 2 and the guide baffle 52 to overcome the problems of light load and reverse axial force on the rotor in low-speed conditions, such as engine ground slowness, caused by conventional radial inward flow, as well as the problem of excessive axial force on the engine rotor at high speeds, even exceeding the allowable load of the bearings, caused by conventional radial outward flow. It achieves adaptive adjustment of the axial force of the engine rotor with changes in speed, possessing the advantages of increasing the forward axial force of the engine rotor with radial outward flow at low speeds and switching to radial inward flow to reduce the forward axial force of the high-pressure rotor at high speeds. It effectively overcomes the common rotor axial force problem in engines with centrifugal impeller structures. In practical applications, the selection of high-expansion and low-expansion materials needs to be considered in conjunction with the actual situation.

[0068] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A centrifugal impeller back cavity swirl control assembly for adaptive engine state changes, characterized in that: Includes a centrifugal impeller (1), a radial expansion casing (2) is provided on the outer side of the centrifugal impeller (1), an inner casing (3) is fixedly connected to the bottom of the radial expansion casing (2), and an air expiratory adjustment mechanism (5) is provided on the back cavity side of the centrifugal impeller (1); The air intake regulating mechanism (5) includes a flow guide baffle (52), the flow guide baffle (52) is provided with a sealing device, and a ring of through holes (5a) is opened at the bottom of the flow guide baffle (52). The linear expansion coefficient of the material selected for the flow guide baffle (52) is greater than that of the material selected for the radial expansion casing (2); When the engine is at high speed, the guide baffle (52) expands more due to the thermal expansion mechanism of the alloy, which closes the cold gap between the outer edge of the O-ring (51) at the top of the guide baffle (52) and the radial expansion casing (2). The radial gap of the inner air intake channel (6a) between the guide baffle (52) and the radial expansion casing (2) is closed, and the back cavity air intake of the centrifugal impeller (1) forms a single radial inward flow along the outer air intake channel (6b).

2. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The bottom of the radial expansion casing (2) is fitted with bolts (4), and the radial expansion casing (2) is fixedly connected to the inner casing (3) by bolts (4). The top of the flow guide baffle (52) is fitted with an O-ring seal (51).

3. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 2, characterized in that: A 0.45mm cold gap is left between the O-ring (51) and the inner wall of the radial expansion casing (2).

4. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The flow guide baffle (52) is fixedly connected to the radial expansion casing (2) and the inner casing (3) at one end facing the inner casing (3) by bolts (4).

5. A centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1 or 4, characterized in that: One side of the flow guide baffle (52) forms an inner air intake channel (6a) with the inner wall of the radial expansion casing (2), and the other side of the flow guide baffle (52) forms an outer air intake channel (6b) with the back cavity side of the centrifugal impeller (1).

6. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The bottom of the inner casing (3) is fixedly equipped with a throttling grate, the bottom end of which is arranged facing the external air intake channel (6b).

7. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 5, characterized in that: The radial expansion casing (2) is inclined on the side of the inner casing (3) facing each other, and the inner diameter of the inner air intake channel (6a) gradually increases from top to bottom.

8. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The through hole (5a) is located at the position of minimum radius of curvature of the flow guide baffle (52) and is arranged circumferentially.

9. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The axial distance between the flow guide baffle (52) and the rotating side of the back cavity of the centrifugal impeller (1) is 3-5 mm.

10. The centrifugal impeller back cavity swirl control assembly for adaptive engine state changes according to claim 1, characterized in that: The outer diameter of the flow guide baffle (52) is the same as the root radius of the centrifugal impeller (1) outlet, and the inner diameter of the flow guide baffle (52) is 50% to 70% of the outer diameter.

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