Turbine adjustable guide vane based on pneumatic adjustment and control method

Abstract

The invention relates to the technical field of aero-engines, and discloses a turbine adjustable guide vane based on pneumatic adjustment and a control method.The blade body of the turbine adjustable guide vane is provided with a hollow rotating shaft with exhaust gaps, meanwhile, the hollow rotating shaft is connected with an air inlet pipe through a shaft sleeve, and the hollow rotating shaft is provided with a circular air inlet window communicated with the air inlet pipe; when the engine turbine guide vane is pneumatically adjusted according to different working conditions, the position of the exhaust gap is changed by rotating the hollow rotating shaft, then the direction of jet flow sprayed out of the exhaust gap and used for pneumatic adjustment is adjusted, and meanwhile the opening degree of the circular air inlet window is adjusted by rotating the hollow rotating shaft. Therefore, the flow regulation of the jet flow for pneumatic regulation is realized.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aero-engines and discloses a turbine adjustable guide vane based on aerodynamic adjustment and a control method. BACKGROUND

[0002] Adaptive variable cycle characteristics are one of important development trends of a new generation of engines, and a throat area of a blade guide in the engine is an important parameter affecting the work of the engine of an aircraft, a ship or a tank. From the development trend of future power technology, the adjustable turbine guide area allows the engine to work in a wider bypass ratio range, and the compressor can be kept at a fixed matching point to achieve high efficiency, is an important means for simultaneously realizing high thrust under supersonic flight and low fuel consumption under subsonic flight, and is an important direction of future development of the aero-engine.

[0003] Traditional variable geometry blade technology usually adopts a mechanical adjustment mode, an additional adjustment mechanism is attached to the outside of a bypass, and the guide vane is rotated by a hollow shaft, the scheme is suitable for fine adjustment of a large range of flow, and has been successfully applied to adjustment of variable geometry components such as a fan, a compressor, a low-pressure turbine and a power turbine. However, the mechanical adjustment scheme needs to add an additional adjustment mechanism in the engine, increases the weight of the engine, and gaps and sealing problems exist between the mechanical structures. The existence of the guide vane tip gap can greatly increase the turbine efficiency loss. At the same time, whether the mechanical adjustable guide vane adopts a whole blade rotation scheme or a split type or a local blade adjustable scheme, the blade cooling flow path integrity is greatly affected, so that the blade cooling design faces challenges.

[0004] In view of the inherent problems of the mechanical adjustment, a foreign country proposes a technical scheme of aerodynamic adjustment, actively sprays a controllable jet flow to a flow channel through a blade surface, changes a throat area of the flow channel, and performs aerodynamic throat control. The main advantage of the scheme is that the influence of the tip gap generated by the rotation of the guide vane on the aerodynamic loss of the turbine can be avoided, and the structure is relatively simple. At present, the related research is still in the conceptual demonstration stage. One of the main difficulties of the technology is how to solve the problems of the jet flow direction control and the flow control of the blade surface of the engine under different working conditions. SUMMARY

[0005] The application aims to provide a turbine adjustable guide vane based on aerodynamic adjustment and a control method, so that the jet flow direction adjustment and the jet flow adjustment of the aerodynamic adjustment of the engine turbine guide vane are realized when the engine turbine guide vane is subjected to aerodynamic adjustment under different working conditions.

[0006] In order to realize the above technical effects, the technical scheme adopted by the application is as follows: A turbine adjustable guide vane based on aerodynamic adjustment, comprising: The blade body is provided with a shaft hole intersecting with a suction surface of the blade body and forming a jet window on the suction surface, and the jet window is located in a throat area corresponding to the suction surface; A hollow rotating shaft is installed in the shaft hole, one end of the hollow rotating shaft is connected with an air inlet pipe through a shaft sleeve, the hollow rotating shaft is provided with a circular air inlet window in communication with the air inlet pipe, the hollow rotating shaft is provided with an air outlet slot in the axial direction, and the air outlet slot faces the jet window; A driving mechanism is used to drive the hollow rotating shaft to rotate at a preset deflection angle to change the angle of the jet ejected by the air outlet slot and the opening degree of the circular air inlet window relative to the air inlet pipe.

[0007] Further, the outer wall surface of the hollow rotating shaft located in the jet window is smoothly connected with the suction surface.

[0008] Further, the blade body is provided with an upper edge plate and a lower edge plate on both sides, respectively, and the shaft hole penetrates through the upper edge plate and the lower edge plate.

[0009] Further, one end of the hollow rotating shaft is located on one side of the upper edge plate, and the other end of the hollow rotating shaft is rotationally connected with the lower edge plate.

[0010] Further, the blade body is provided with a first chamber, a second chamber and a third chamber inside, the lower edge plate is provided with a first air inlet in communication with the first chamber, and the upper edge plate is provided with a second air inlet and a third air inlet in communication with the second chamber and the third chamber.

[0011] Further, the length of the air outlet slot is the same as the length of the jet window.

[0012] A turbine adjustable guide vane control method based on pneumatic regulation is used to control the turbine adjustable guide vane, comprising: The opening degree of the circular air inlet window is determined to be 100% when the engine is in a preset reference working condition, and the air inlet flow of the circular air inlet window in the preset reference working condition is obtained; An air inlet flow analysis model based on the deflection angle of the hollow rotating shaft is constructed, the radius of the circular air inlet window, the air inlet flow of the circular air inlet window when the engine is in the preset reference working condition, and the required air inlet flow of the circular air inlet window when the engine is in a target working condition are analyzed by using the air inlet flow analysis model, and the deflection angle of the hollow rotating shaft when the engine changes from the preset reference working condition to the target working condition is obtained; According to the deflection angle of the hollow rotating shaft when the engine changes from the preset reference working condition to the target working condition, the driving mechanism drives the hollow rotating shaft to rotate to adjust the angle of the jet ejected by the air outlet slot and the air inlet flow of the circular air inlet window.

[0013] Further, the air flow adjustment model based on the deflection angle of the hollow rotating shaft is constructed as: ; Wherein, is the air flow required for the circular air inlet window in the target working condition, is the air flow of the circular air inlet window in the preset reference working condition, is the radius of the circular air inlet window, is the inverse cosine function, is the deflection angle of the hollow rotating shaft when the engine changes from the preset reference working condition to the target working condition.

[0014] Compared with the prior art, the present application has the beneficial effects that: The present application sets a hollow rotating shaft with exhaust slots on the turbine adjustable guide vane, and the hollow rotating shaft is connected with an air inlet pipe through a shaft sleeve, and the hollow rotating shaft is provided with a circular air inlet window in communication with the air inlet pipe. When the engine turbine guide vane is subjected to aerodynamic adjustment in response to different working conditions, the position of the exhaust slot is changed by rotating the hollow rotating shaft, thereby realizing the direction adjustment of the jet flow for aerodynamic adjustment ejected by the exhaust slot. At the same time, the opening of the circular air inlet window is adjusted by rotating the hollow rotating shaft, thereby realizing the flow adjustment of the jet flow for aerodynamic adjustment. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structure schematic diagram of the turbine adjustable guide vane based on aerodynamic adjustment in the embodiment; Figure 2 is the A-A sectional view in Figure 1 ; Figure 3 is the first axonometric view of the turbine adjustable guide vane based on aerodynamic adjustment in the embodiment; Figure 4 is the second axonometric view of the turbine adjustable guide vane based on aerodynamic adjustment in the embodiment; Figure 5 is a structure schematic diagram of the hollow rotating shaft, the shaft sleeve and the air inlet pipe in the embodiment; Figure 6 is the B-B sectional view in Figure 5 ; Figure 7 is a schematic diagram of the turbine adjustable guide vane aerodynamic adjustment in the high load working condition of the engine; Figure 8 is a schematic diagram of the turbine adjustable guide vane aerodynamic adjustment in the low load working condition of the engine; Figure 9 is a schematic diagram of the air inlet of the hollow rotating shaft in the low load working condition of the engine; Figure 10 is a schematic diagram of the air inlet of the hollow rotating shaft in the high load working condition of the engine; Figure 11 Figure 3 is a sectional view of the hollow rotating shaft, the shaft sleeve and the air inlet pipe for the high load condition of the engine; Figure 12 Figure 4 is a flow chart of the control method of the turbine variable guide vane based on the aerodynamic adjustment in the embodiment.

[0016] Wherein, 11-vane, 12-upper edge plate, 13-lower edge plate, 14-jet window, 15-first chamber, 16-second chamber, 17-third chamber, 2-hollow rotating shaft, 21-circular air inlet window, 22-exhaust slot, 3-shaft sleeve, 4-air inlet pipe. DETAILED DESCRIPTION

[0017] The application will be further described in conjunction with the embodiments and the drawings. However, it should not be understood that the above-mentioned subject matter of the application is limited to the following embodiments only, and any technology realized based on the content of the application falls within the scope of the application.

[0018] EMBODIMENT Referring to Figures 1 to 11 A turbine variable guide vane based on aerodynamic adjustment comprises: A vane 11, the vane 11 is provided with an upper edge plate 12 and a lower edge plate 13 on both sides, the vane 11 is provided with a shaft hole penetrating through the upper edge plate 12 and the lower edge plate 13, the shaft hole intersects with a suction surface of the vane 11 and forms a jet window 14 in the suction surface, and the jet window 14 is located in a throat area corresponding to the suction surface.

[0019] A hollow rotating shaft 2 is installed in the shaft hole; an M end of the hollow rotating shaft 2 extends to the outside of the upper edge plate 12 and is inserted into a turbine main flow channel, then an air inlet pipe 4 is connected through a shaft sleeve 3, an N end of the hollow rotating shaft 2 is rotationally connected with the lower edge plate 13; the hollow rotating shaft 2 is provided with a circular air inlet window 21 communicating with the air inlet pipe 4, an exhaust slot 22 is provided in the hollow rotating shaft 2 along the axial direction, and the exhaust slot 22 faces the jet window 14, the length of the exhaust slot 22 is the same as the length of the jet window 14. The airflow in the turbine main flow channel flows into the circular air inlet window 21 after passing through the air inlet pipe 4, and then flows into the hollow rotating shaft 2, and then is sprayed out from the exhaust slot 22 to form a jet, the jet enters the throat area through the jet window 14, thereby realizing the aerodynamic adjustment of the throat area between adjacent two turbine variable guide vanes, and then realizing the turbine flow regulation. It should be noted that the lower end of the shaft hole can be fixed with a base, the base is flush with the lower edge plate 13, and the N end of the hollow rotating shaft 2 is inserted into the base to ensure that the hollow rotating shaft 2 can rotate normally, and the gap between the hollow rotating shaft 2 and the base needs to meet the demand of aerodynamic adjustment. The turbine main flow channel refers to the flow channel where the turbine variable guide vane is located.

[0020] A driving mechanism is used to drive the hollow rotating shaft 2 to rotate at a preset deflection angle, so as to change the angle of the jet flow of the exhaust slot 22 and the opening degree of the circular air inlet window 21 relative to the nozzle of the air inlet pipe 4. It should be noted that the driving mechanism can be an electric motor, or a combination of an electric motor and a speed reduction assembly, or other driving mechanisms.

[0021] It should be noted that, as shown in Figure 6 and Figure 9 , in the low load working condition of the engine, the temperature at the inlet of the turbine is low, the circular air inlet window 21 of the hollow rotating shaft 2 is opposite to the nozzle of the air inlet pipe 4, the opening degree of the circular air inlet window 21 relative to the nozzle of the air inlet pipe 4 is 100%, and the cooling gas in the air inlet pipe 4 flows into the hollow rotating shaft 2 through the circular air inlet window 21, so that the air inlet flow of the circular air inlet window 21 is maximum. Figure 10 and Figure 11 , in the high load working condition of the engine, the temperature at the inlet of the turbine is high, when the hollow rotating shaft 2 is deflected by a certain angle, the circular air inlet window 21 is not opposite to the nozzle of the air inlet pipe 4, and part of the circular air inlet window 21 is blocked by the shaft sleeve 3, so that the opening degree of the circular air inlet window 21 relative to the nozzle of the air inlet pipe 4 is less than 100%, and the air inlet flow of the circular air inlet window 21 is reduced. The present application utilizes the rotation of the hollow rotating shaft 2 to control the opening degree of the circular air inlet window 21 in combination with the shaft sleeve 3, so as to realize the active control of the jet flow in different working conditions of the engine.

[0022] It should be noted that the hollow rotating shaft 2 is a hollow column with both ends closed, the circular air inlet window 21 is an air inlet structure of the hollow rotating shaft 2, and the exhaust slot 22 is an air outlet structure of the hollow rotating shaft 2. In the present application, dynamic sealing or static sealing elements or methods are used to realize sealing between the hollow rotating shaft 2 and the shaft sleeve 3, and other places that need to be sealed.

[0023] In some embodiments, the outer wall surface of the hollow rotating shaft 2 located in the jet window 14 is smoothly connected with the suction surface. The part of the outer side of the hollow rotating shaft 2 and the blade body 11 together form a smooth aerodynamic shape on the suction surface of the blade, so as to reduce the blade loss.

[0024] In some embodiments, as shown in Figure 2 and Figure 4As shown, the blade 11 has a first chamber 15, a second chamber 16, and a third chamber 17. The lower edge plate 13 has a first air inlet connecting to the first chamber 15, and the upper edge plate 12 has a second air inlet and a third air inlet connecting the second chamber 16 and the third chamber 17. The blade 11 of the present invention adopts a three-chamber structure. The first chamber 15 is inlet through the lower edge plate 13, and the second chamber 16 and the third chamber 17 are inlet through the upper edge plate 12. Without affecting the continuity of the blade pressure surface, the blade 11 and the hollow rotating shaft 2 together form the aerodynamic shape of the suction surface, ensuring the continuity and smoothness of the blade suction surface and reducing blade shape loss.

[0025] The blade 11 may have the cooling forms of conventional blades, including but not limited to air film holes, turbulence ribs, turbulence columns, tail slits, serpentine channels, impact bushings, plate cooling, double-wall cooling structures, etc., and the cooling flow path of the blade 11 and the air intake flow path of the hollow rotating shaft 2 are independent of each other.

[0026] The turbine adjustable guide vane based on aerodynamic adjustment of the present invention can adjust the jet angle and jet flow rate by rotating the hollow shaft 2 when aerodynamic adjustment is performed to cope with different working conditions. That is, a large flow vertical jet is achieved when the engine is under low load, and a small flow wall-mounted jet is achieved when the engine is under high load.

[0027] Specifically, the working process of the turbine adjustable guide vane based on aerodynamic regulation is divided into two states: under high engine load conditions, the drive mechanism drives the hollow shaft 2 to rotate to the position shown in the figure. Figure 7 As shown, the effective area of ​​the circular air intake window 21 is partially blocked, resulting in a smaller intake flow. Simultaneously, the position of the exhaust slit 22 directs the jet angle downstream of the blades, causing the jet to adhere to the wall surface and form a film of air, aiding in blade cooling. At this time, the turbine mains throat area is A1. Under low engine load conditions, the drive mechanism drives the hollow shaft 2 to rotate as shown... Figure 8 As shown, the circular air intake window 21 is fully open, achieving a larger air intake flow. At the same time, the position of the exhaust slit 22 makes the jet angle perpendicular to the incoming flow. At this time, the throat area of ​​the turbine main flow channel is A2, and A2 < A1, which produces the effect of blocking the blade throat area, realizing turbine flow regulation under low load conditions.

[0028] The present application realizes small-flow wall-attached jet flow in high-load working condition of the engine and large-flow vertical jet flow in low-load working condition of the engine through the two working modes, and further realizes turbine flow regulation in different working conditions of the engine. Compared with the conventional adjustable guide vane, the adjustable guide vane based on aerodynamic regulation retains the structural integrity of the blade 11 to the greatest extent, so that the blade 11 and the upper and lower edge plates can be designed integrally, avoiding the flow loss caused by the edge plate gap due to the rotation of the conventional adjustable guide vane. The hollow rotating shaft 2 and the blade 11 are smooth and continuous on the suction surface of the blade, ensuring the aerodynamic performance of the blade. The area occupied by the hollow rotating shaft 2 is relatively small, which is beneficial to increase the degree of freedom of the cooling structure design of the blade 11.

[0029] The high-load working condition of the engine and the low-load working condition of the engine correspond to the high-speed flight condition and the low-speed flight condition of the aircraft, respectively. The turbine inlet temperature is low in the low-load working condition of the variable cycle engine, and the cooling gas flow for turbine adjustable guide vane cooling is small. A part of the cooling gas for turbine adjustable guide vane cooling is introduced into the hollow rotating shaft 2, and a jet flow is formed through the exhaust slot 22 to inject into the throat of the main flow passage between the turbine adjustable guide vanes, so as to reduce the area of the main flow passage throat, reduce the main flow passage flow, and realize aerodynamic regulation of the main flow passage flow. When the variable cycle engine changes from the low-load working condition to the high-load working condition, the turbine inlet temperature rises, more cooling gas needs to be distributed for turbine adjustable guide vane cooling, and the area of the main flow passage throat needs to be increased, and the main flow passage flow needs to be increased. Therefore, the hollow rotating shaft 2 is deflected at a preset deflection angle, the opening degree of the circular air inlet window 21 on the hollow rotating shaft 2 is reduced, the air inlet flow into the hollow rotating shaft 2 is reduced, the position of the exhaust slot 22 is changed, the jet flow angle is adjusted, the area of the main flow passage throat is increased, the main flow passage flow is increased, and the aerodynamic regulation of the main flow passage flow is realized.

[0030] Based on the same inventive concept, as Figure 12 indicated, the present embodiment also provides a turbine adjustable guide vane control method based on aerodynamic regulation, used for controlling the turbine adjustable guide vane, comprising the following steps: Step one: determining that the opening degree of the circular air inlet window 21 is 100% when the engine is in a preset reference working condition, and obtaining the air inlet flow of the circular air inlet window 21 in the preset reference working condition . The preset reference working condition refers to the low-load working condition of the engine. The air inlet flow of the circular air inlet window 21 in the preset reference working condition can be obtained through simulation. The opening degree of the circular air inlet window 21 relative to the pipe opening of the air inlet pipe 4 is as Figures 9 to 11 indicated.

[0031] Step two: constructing an aerodynamic regulation air inlet flow analysis model based on the deflection angle of the hollow rotating shaft 2; analyzing the radius of the circular air inlet window 21 by using the aerodynamic regulation air inlet flow analysis model , the intake flow of the circular intake window 21 when the engine is in the preset reference working condition , the required intake flow of the circular intake window 21 when the engine is in the target working condition , the deflection angle of the hollow rotating shaft 2 when the engine changes from the preset reference working condition to the target working condition Specifically, first, the aerodynamic adjustment intake flow analysis model based on the deflection angle of the hollow rotating shaft 2 is constructed as follows: Wherein: is the required intake flow of the circular intake window 21 when the engine is in the target working condition, which can be obtained by simulating the engine in the target working condition is the intake flow of the circular intake window 21 when the engine is in the preset reference working condition; is the radius of the circular intake window 21; is the inverse cosine function; is the deflection angle of the hollow rotating shaft 2 when the engine changes from the preset reference working condition to the target working condition.

[0032] Then, according to the radius of the circular intake window 21 , the intake flow of the circular intake window 21 when the engine is in the preset reference working condition , the required intake flow of the circular intake window 21 when the engine is in the target working condition , the aerodynamic adjustment intake flow analysis model is used for analysis to obtain the deflection angle of the hollow rotating shaft 2 when the engine changes from the preset reference working condition to the target working condition .

[0033] It should be noted that the target working condition refers to the high load working condition of the engine, and in one high load working condition, the opening of the circular intake window 21 relative to the pipe opening of the intake pipe 4 is as shown in Figure 10 .

[0034] It should be noted that the position of the circular intake window 21 or the exhaust slot 22 on the hollow rotating shaft 2 when the engine is in the preset reference working condition is the reference position, and the position of the circular intake window 21 or the exhaust slot 22 on the hollow rotating shaft 2 when the engine is in the target working condition is the target position. The rotation angle corresponding to the circular intake window 21 or the exhaust slot 22 on the hollow rotating shaft 2 from the reference position to the target position is the deflection angle of the hollow rotating shaft .

[0035] Step three: according to the deflection angle of the hollow rotating shaft 2 when the engine changes from the preset reference working condition to the target working condition ​​​The driving mechanism drives the hollow rotating shaft 2 to rotate to adjust the angle of the jet flow sprayed by the exhaust slot 22 and the air intake flow of the circular air intake window 21.

[0036] The hollow rotating shaft 2 provided with the exhaust slot 22 is connected with the air intake pipe 4 through the shaft sleeve 3, and the hollow rotating shaft 2 is provided with the circular air intake window 21 communicated with the air intake pipe 4. When the engine turbine guide vane adjusts the aerodynamic condition, the position of the exhaust slot 22 is changed by rotating the hollow rotating shaft 2, and then the direction of the jet flow sprayed by the exhaust slot 22 for aerodynamic adjustment is adjusted. At the same time, the opening of the circular air intake window 21 relative to the air intake pipe 4 is adjusted by rotating the hollow rotating shaft 2, and then the flow of the jet flow for aerodynamic adjustment is adjusted.

[0037] The above only is the preferred embodiment of the present application, and does not limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A turbine adjustable guide vane based on aerodynamic regulation, characterized in that, include: The blade (11) is provided with a shaft hole, the shaft hole intersects with the suction surface of the blade (11), and a jet window (14) communicating with the shaft hole is formed on the suction surface, and the jet window (14) is located in the throat area corresponding to the suction surface; A hollow rotating shaft (2) is installed in the shaft hole; the inner cavity of the hollow rotating shaft (2) is connected to an air inlet pipe (4) through a bushing (3); the hollow rotating shaft (2) is provided with a circular air inlet window (21) communicating with the air inlet pipe (4); the hollow rotating shaft (2) is provided with an exhaust slit (22) along the axial direction, and the exhaust slit (22) faces the jet window (14); The drive mechanism is used to drive the hollow shaft (2) to rotate at a preset deflection angle, so as to change the angle of the jet ejected from the exhaust slit (22) and at the same time change the opening of the circular air intake window (21).

2. The turbine adjustable guide vane based on aerodynamic regulation according to claim 1, characterized in that, The hollow rotating shaft (2) is located on the outer wall surface inside the jet window (14) and is smoothly connected to the suction surface.

3. The turbine adjustable guide vane based on aerodynamic regulation according to claim 1, characterized in that, The blade (11) is provided with an upper edge plate (12) and a lower edge plate (13) on both sides, and the shaft hole passes through the upper edge plate (12) and the lower edge plate (13).

4. The turbine adjustable guide vane based on aerodynamic regulation according to claim 3, characterized in that, One end of the hollow rotating shaft (2) is located on one side of the upper edge plate (12), and the other end of the hollow rotating shaft (2) is rotatably connected to the lower edge plate (13).

5. The turbine adjustable guide vane based on aerodynamic regulation according to claim 3, characterized in that, The blade (11) is provided with a first chamber (15), a second chamber (16) and a third chamber (17). The lower edge plate (13) is provided with a first air inlet that connects to the first chamber (15). The upper edge plate (12) is provided with a second air inlet and a third air inlet that connect the second chamber (16) and the third chamber (17).

6. The turbine adjustable guide vane based on aerodynamic regulation according to claim 1, characterized in that, The length of the exhaust slit (22) is the same as the length of the jet window (14).

7. A method for controlling turbine adjustable guide vanes based on aerodynamic regulation, used to control the turbine adjustable guide vanes according to any one of claims 1-6, characterized in that, include: The opening degree of the circular air intake window (21) of the engine is determined to be 100% under the preset reference operating conditions, and the air intake flow rate of the circular air intake window (21) under the preset reference operating conditions is obtained. A pneumatic adjustment intake flow analysis model based on the deflection angle of the hollow shaft (2) is constructed; the radius of the circular intake window (21), the intake flow of the circular intake window (21) when the engine is in the preset reference working condition, and the intake flow required by the circular intake window (21) when the engine is in the target working condition are analyzed using the pneumatic adjustment intake flow analysis model to obtain the deflection angle of the hollow shaft (2) when the engine changes from the preset reference working condition to the target working condition; According to the deflection angle of the hollow shaft (2) when the engine changes from the preset reference condition to the target condition, the drive mechanism drives the hollow shaft (2) to rotate, so as to adjust the angle of the jet ejected from the exhaust slit (22) and the intake flow of the circular air intake window (21).

8. The turbine adjustable guide vane control method based on aerodynamic regulation according to claim 7, characterized in that, The aerodynamic regulating intake flow analysis model based on the deflection angle of the hollow rotating shaft (2) is constructed as follows: ； in, The required intake flow rate for the circular intake window (21) under the target operating conditions. To preset the intake flow rate of the circular intake window (21) under reference operating conditions, The radius of the circular air intake window (21) is... It is an inverse cosine function. The deflection angle of the hollow shaft (2) when the engine changes from the preset reference condition to the target condition.

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