Dual angle adjustment inlet guide vane for broadening adaptive fan stability margin

Abstract

The double-angle adjusting inlet guide vane comprises a main blade D1, a main blade D2, an auxiliary blade A, a molded surface compensation block B, a molded surface compensation block C and a connecting mechanism, the main blade D2 is arranged on the main blade D1, the front edge part of the auxiliary blade A makes contact with an arc-shaped groove in one side of the main blade D1, and the rear edge part of the auxiliary blade A makes contact with the arc-shaped groove in the other side of the main blade D1. The auxiliary blade A, the molded surface compensation block B, the molded surface compensation block C and the main blade D2 are sequentially connected through a connecting mechanism, a hollow main shaft is further arranged on the blade top of the main blade D1, an auxiliary shaft is arranged in the hollow main shaft and connected with the blade top of the auxiliary blade A. The hollow main shaft and the auxiliary shaft drive the blade D1, the main blade D2 and the auxiliary blade A to rotate. The pre-rotation degrees of different blade height positions are adjusted, the stability margin and the working performance of the self-adaptive fan in the full bypass ratio working condition are remarkably widened, and when the auxiliary blade A rotates, the profile compensation blocks B and C are driven to move, so that area loss, caused by local deflection, of the appearance face of the whole guide blade is compensated.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation power devices, and in particular relates to a double-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan. Background Art

[0002] With the rapid development of aviation technology, higher requirements are placed on the combat capabilities of military aircraft. In order to meet the dual performance requirements of the next generation of fighter jets for high unit thrust and low cruise fuel consumption of the engine, and in response to new characteristics of modern local warfare such as rapid search and integrated reconnaissance and strike, it has become an inevitable trend to develop aviation engine technology with higher economic benefits, all-weather, multi-purpose, high-range, high-maneuverability thrust vectoring, and vertical take-off and landing capabilities.

[0003] In the design of aircraft engines, different flight missions have different design requirements. When the aircraft is in a cruising state, a lower fuel consumption rate is required to ensure a longer cruising time. When the aircraft is in a climbing or supersonic state, a larger unit thrust is required to meet the mission requirements. However, conventional engines seem to be unable to meet both requirements.

[0004] The emergence of variable cycle engines (VCE) can solve this problem and play a huge role in modern weapons and equipment. Variable cycle engines integrate the performance advantages of medium bypass ratio turbofan engines in subsonic flight state and turbojet engines in supersonic flight state. The two are combined into one, and the bypass ratio, pressure ratio, flow rate and cycle working mode of the engine can be flexibly adjusted, so that such engines can ensure that the aircraft maintains high performance flight in a wider flight envelope, thereby achieving a balance between different flight missions and different requirements for the engine.

[0005] The adaptive cycle engine is inseparable from the variable cycle engine and is the development and extension of the variable cycle engine. At present, the United States is in a leading position in the research of adaptive variable cycle engines abroad. The research on adaptive variable cycle engines has mainly gone through the following process.

[0006] The adaptive cycle engine was first studied in 2007 as a project of the U.S. Air Force Research Laboratory (AFRL). The project was called the ADVENT program, and its goal was to develop technology that could independently change the fan / core engine flow and pressure ratio to develop a new generation of military fighters. GE and RR, as contractors for the project, conducted a two-year test and verification of key components such as the engine's fan, compressor, and variable flow turbine. For GE's ADVENT model, its main structural feature is that it has three ducts. The inner duct and the second duct can be similar to the double outer duct variable cycle engine YF120. The third duct is its unique structure. The airflow of the third duct is always in the outer duct and does not enter the core engine. The flow of the third duct can be changed according to different mission requirements to adjust the engine's bypass ratio. It can also be used as a cooling airflow.

[0007] In 2009, the ADVENT project launched the second phase of technical verification based on the research results of the first phase, further improved the key technical solutions of the engine components, and designed an adaptive cycle engine with variable fan pressure ratio and flow rate. Later, the full-scale ground test of the engine verification machine was successfully carried out.

[0008] In 2012, the U.S. Air Force formulated a four-year AETD plan in order to further develop adaptive cycle engine technology and develop a more complete propulsion system for the new generation of fighter jets. The initial goal of the plan is still to test and verify key components such as engine fans and core engines. The ultimate goal is to complete the whole machine test in 2017. GE and PW have been designated to participate in the research of the AETD plan.

[0009] In 2019, GE disclosed the basic structure of the next-generation adaptive engine. Public data shows that the engine compresses the gas through a 3-stage fan and a 7-stage high-pressure compressor. There is no core drive fan. It only relies on the fan and the high-pressure compressor for boosting. It can be inferred that its boost is relatively high. According to GE's official website, this engine has two working modes, high thrust and high efficiency. In the high thrust mode, more flow flows into the second duct and the inner duct to generate greater thrust, while the flow of the third duct is very small; in the high efficiency mode, the flow of the third duct increases, and the flow of the second duct is very small, thereby improving the fuel efficiency of the engine.

[0010] On the other hand, adaptive engine technology has been demonstrated by domestic and foreign researchers, who all pointed out that adaptive fan components are one of the key technologies to achieve its comprehensive performance. In addition to completing the supercharging effect of traditional fans, they must also complete the flow regulation and variable bypass ratio functions unique to adaptive variable cycle engines, achieve good matching of multiple working points, and operate stably during the working mode switching process. It is strongly coupled with the adaptive variable cycle engine as a whole. It can be seen that the performance requirements of adaptive fans are strict, and it is difficult to meet new performance requirements by relying solely on traditional imported adjustable guide vanes. For this reason, in view of the complex radial changes in the internal flow field when the adaptive fan is converted from the design bypass ratio working condition (large bypass ratio working condition) to the small bypass ratio working condition, a new type of imported adjustable guide vane suitable for the variable bypass ratio mode of the adaptive fan is developed and designed to ensure the stable operation of the adaptive fan, which is a key technology to achieve multiple performance requirements. Summary of the invention

[0011] The purpose of the present invention is to solve the problem of the area loss of the entire guide vane outer surface caused by adjusting the double-angle inlet guide vane to widen the stability margin of the adaptive fan, and to provide a new double-angle adjustable inlet guide vane for widening the stability margin of the adaptive fan;

[0012] In order to achieve the above-mentioned object, the present invention adopts the following technical solution: a dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan, characterized in that it comprises: a main blade D1, a main blade D2, an auxiliary blade A, a profile compensation block B, a profile compensation block C and a connecting mechanism;

[0013] The main blade D2 is arranged on the main blade D1, one side of the auxiliary blade A contacts the arc-shaped groove on one side of the main blade D1, and the auxiliary blade A, the profile compensation block B, the profile compensation block C and the main blade D2 are sequentially connected to each other through a connecting mechanism;

[0014] A hollow main shaft is also provided on the blade top of the main blade D1 , a secondary shaft is provided inside the hollow main shaft, and the secondary shaft is connected to the blade top of the secondary blade A.

[0015] Furthermore, the connection mechanism comprises: a limiting slide groove and a rotating seat, the limiting slide groove is arranged on the profile compensation block C, and the rotating seat is respectively arranged on the auxiliary blade A and the main blade D2.

[0016] Furthermore, the bottom of the auxiliary blade A is connected to the profile compensation block B through a rotating seat, the profile compensation block B is slidably connected to the limiting slide groove, and the profile compensation block C is connected to the top of the main blade D2 through a rotating seat.

[0017] Furthermore, the trailing edge height of the profile compensation block B and the profile compensation block C is 20% of the height of the main blade D2, which is used to avoid the inability to effectively perform area compensation when the main and auxiliary blades have a large partition adjustment angle due to the area compensation block being too small.

[0018] Furthermore, the dividing point between the leading edge of the main blade D2 and the auxiliary blade A is the height corresponding to point a, and point a is the lowest height of the separation zone of the fan in a high bypass ratio state.

[0019] Beneficial effects:

[0020] 1. The present invention adjusts the rotation angle of the secondary shaft to drive the secondary blade A to rotate, thereby eliminating or weakening the flow separation at the large blade height of the fan. At the same time, the rotation angle of the hollow main shaft is slightly adjusted to drive the main blade D1 and the main blade D2 to rotate, thereby reducing the low-speed area at the back of the blade at the low blade height of the blade, improving the uneven radial distribution of the rotor inlet airflow when the adaptive fan is converted from a large bypass ratio condition to a small bypass ratio condition, significantly improving the stability margin and working performance of the widened adaptive fan within the full bypass ratio condition, and improving the quality of the rotor inlet airflow.

[0021] 2. When the auxiliary blade A of the present invention rotates, it will drive the profile compensation block B and the profile compensation block C to move, thereby compensating for the area loss of the entire guide vane outer surface caused by local deflection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 It is a schematic diagram of the three-dimensional structure of the double-angle adjustable inlet guide vanes for widening the stability margin of the adaptive fan.

[0023] Attached Figure 2 Schematic diagram of fan separation zone distribution under design conditions of large bypass ratio and small bypass ratio.

[0024] In the figure: 1. hollow main shaft, 2. secondary shaft, 3. connecting mechanism, 3-1. limiting slide groove, 3-2. rotating seat. DETAILED DESCRIPTION

[0025] The present invention will be further explained below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the present invention provides a dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan, comprising: a main blade D1, a main blade D2, an auxiliary blade A, a profile compensation block B, a profile compensation block C and a connecting mechanism 3.

[0027] The main blade D2 is arranged on the main blade D1, the arc groove on one side of the auxiliary blade A contacts the arc groove on one side of the main blade D1, and the auxiliary blade A, the profile compensation block B, the profile compensation block C and the main blade D2 are sequentially connected to each other through the connecting mechanism 3.

[0028] A hollow main shaft 1 is also provided on the blade top of the main blade D1 , and a secondary shaft 2 is provided inside the hollow main shaft 1 . The secondary shaft 2 is connected to the blade top of the secondary blade A.

[0029] Among them, the main blade D1 and the main blade D2 are connected as a whole through a trapezoidal keyway, which is convenient for assembly. The connecting mechanism 3 includes: a limiting slide groove 3-1 and a rotating seat 3-2. The limiting slide groove 3-1 is arranged on the profile compensation block C, and the rotating seat 3-2 is respectively arranged on the auxiliary blade A and the main blade D2. The bottom of the auxiliary blade A is connected to the profile compensation block B through the rotating seat 3-2, and the profile compensation block B is slidably connected to the limiting slide groove 3-1. The profile compensation block C is connected to the blade top of the main blade D2 through the rotating seat 3-2. The above-mentioned arrangement increases the flexibility of the profile compensation block B and the profile compensation block C when the auxiliary blade is adjusted, and the auxiliary blade A will drive the profile compensation block B to move through its rotating seat 3-2 during the rotation process. Under the action of friction, the profile compensation block B will slide out of a part of the limiting slide groove 3-1 on the profile compensation block C, thereby compensating for the area loss caused by local deflection to the guide vane outer surface.

[0030] The outer diameter of the hollow main shaft 1 is twice the radius of the secondary shaft 2. About 25% of the radius of the hollow main shaft 1 is connected to the main blade D1, and 75% of the radius is in contact with the secondary blade A. The hollow main shaft 1 is connected to the main blade rocker arm. The main blade rocker arm controls the main blade D1 through the hollow main shaft 1, and the main blade D1 drives the main blade D2 to rotate through the keyway to realize the overall rotation of the main blade part. The secondary shaft 2 is located at the top of the secondary blade A and is inside the hollow main shaft 1. The secondary shaft 2 is also connected to the secondary blade rocker arm. The secondary blade rocker arm controls the rotation of the secondary blade A through the secondary shaft 2. When the secondary blade A rotates, it will drive the profile compensation block B and the profile compensation block C to move. The main blade rocker arm and the secondary blade rocker arm are respectively connected to their corresponding drive rings through joint bearings, so that the entire guide vane can be controlled to rotate separately by simply pushing the drive ring.

[0031] When adjusting the hollow main shaft 1 and the secondary shaft 2, it is necessary to fully consider the maximum adjustable angles of the two blades. If the rotation angles of blade D1 and main blade D2 are too large, it will affect the flow of the top part of the adaptive fan blade. If the rotation angle of secondary blade A is too large, it will affect the flow of the root part of the fan blade. However, if the rotation angle is too small, a good control effect cannot be achieved. Therefore, when adjusting, the maximum adjustable angles of the hollow main shaft 1 and secondary shaft 2 should be determined in combination with actual engineering needs.

[0032] like Figure 2 As shown in the figure, when the adaptive fan switches from a large bypass ratio design state to a small bypass ratio, its separation area will change radially. The fan has a large bypass ratio design state and its separation area distribution is shown in the figure. Figure 2 (a), where point a is the lowest height of the separation zone in the fan's large bypass ratio state, and the distribution of the separation zone in the small bypass ratio state is shown in Figure 2. Figure 2(b), where point b is the lowest height of the separation zone in the fan's small bypass ratio state, and point a is lower than point b, so the height corresponding to point a is taken as the dividing point between the leading edge of the main blade and the auxiliary blade A after comprehensive consideration. And in order to enhance the control ability of the guide vane over the airflow, the length of the auxiliary blade A is extended to 35%-45% of the entire fan blade top chord length. Then 20% of the length of the main blade D2 is used as the trailing edge height of the profile compensation block B and the profile compensation block C, so as to avoid the inability to effectively compensate for the area when the main and auxiliary blade partition adjustment angles are large due to the area compensation block being too small.

[0033] The transformation rule of the hollow main shaft 1 and the secondary shaft 2 of the present invention is:

[0034] When the fan changes from a large bypass ratio design state to a smaller bypass ratio: the flow separation vortex in the channel moves to the large blade height area of ​​the fan, changing the rotation angle of the secondary shaft 2, so that the inlet guide vane provides a suitable angle of attack to the fan inlet, eliminating or weakening the flow separation at the large blade height of the fan, and improving the stability of the fan; while in the small blade height of the fan, the airflow attack angle changes little, there is no large flow separation, the flow is relatively smooth, and the required control intensity is not large. The rotation angle of the hollow main shaft 1 is adjusted to provide a suitable airflow attack angle for the fan inlet and reduce the low-speed area at the back of the fan rotor blades.

[0035] In the state of a larger design bypass ratio, there is a small separation area in the fan blades. By adjusting the hollow main shaft 1 to change the rotation angle of blade D1 and main blade D2, appropriate pre-rotation is applied to the fan inlet, thereby improving the airflow quality at the fan inlet and expanding the stability of the fan.

[0036] Based on the above provided solution, the specific embodiments are as follows:

[0037] For a variable circulation fan with a bypass ratio ranging from 0.07 to 0.9, the performance requirements are that after adjustment of the inlet guide vanes at any bypass ratio, the fan efficiency is not less than 86%, the pressure ratio is not less than 1.7, and the stability margin increase value is not less than 4%. When the fan is in the state of 0.9 bypass ratio (high bypass ratio turbofan engine mode), there is only a small range of flow separation in the blades during the throttling process. The pre-swirl degree applied by blade D1 and main blade D2 can be adjusted by adjusting the hollow main shaft 1 to eliminate or reduce the flow separation in the rotor blades, thereby expanding the stability margin of the fan at this bypass ratio. When the bypass ratio is gradually reduced, the relative airflow angle at the fan inlet rotor blade and the blade root changes less, while the relative airflow angle at the blade tip changes more, that is, the flow separation vortex moves toward the blade tip. Therefore, when the variable cycle fan is in the state of 0.07 bypass ratio (turbojet engine mode), the relative airflow angle at the blade root part of the fan inlet blade changes less, and the flow field at the blade root part of the blade can be adjusted by slightly adjusting the hollow main shaft 1, while the relative airflow angle at the blade tip changes relatively more, and the flow field at the blade tip part can be adjusted by adjusting the secondary shaft 2. The two shafts cooperate with each other to provide suitable airflow conditions for the fan, expand the stability margin of the fan, and improve the combat capability of the variable cycle engine. In the 0.07-0.9 bypass ratio mode, after coordinated adjustment of the hollow main shaft 1 and the secondary shaft 2, the fan efficiency is maintained at 87.8%-90.2%, the compression ratio is as high as 1.81-1.93, and the stability margin increase values ​​of each operating condition are all greater than 4%. In this coordinated adjustment process, the smaller the fan bypass ratio, the larger the flow vortex at the back of the large blade of the fan rotor, and of course the larger the rotor inlet angle of attack. This is a continuously changing process, so the adjustment angle of the guide vane also changes continuously in one direction.

[0038] The present invention adjusts the rotation angle of the secondary shaft to drive the secondary blade A to rotate, so as to eliminate or weaken the flow separation of the large blade height of the fan. At the same time, the rotation angle of the hollow main shaft is slightly adjusted to drive the main blade D1 and the main blade D2 to rotate, so as to reduce the low-speed area at the back of the blade, thereby improving the uneven radial distribution of the rotor inlet airflow when the adaptive fan is converted from a large bypass ratio condition to a small bypass ratio condition, significantly improving the stability margin and working performance of the widened adaptive fan within the full bypass ratio condition, and improving the rotor inlet airflow quality. When the secondary blade A rotates, it will drive the profile compensation block B and the profile compensation block C to move, thereby compensating for the area loss of the entire guide vane outer surface caused by local deflection.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Double-angle adjustable inlet guide vanes for widening the stability margin of adaptive fans, characterized in that: include: Main blade D1, main blade D2, auxiliary blade A, profile compensation block B, profile compensation block C and connecting mechanism (3); The main blade D2 is arranged on the main blade D1, one side of the auxiliary blade A contacts the arc-shaped groove on one side of the main blade D1, and the auxiliary blade A, the profile compensation block B, the profile compensation block C and the main blade D2 are sequentially connected to each other through a connecting mechanism (3); A hollow main shaft (1) is also provided on the blade top of the main blade D1, a secondary shaft (2) is provided inside the hollow main shaft (1), and the secondary shaft (2) is connected to the blade top of the secondary blade A.

2. The dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan according to claim 1, characterized in that: The connection mechanism (3) comprises: a limiting slide groove (3-1) and a rotating seat (3-2); the limiting slide groove (3-1) is arranged on the profile compensation block C; and the rotating seat (3-2) is respectively arranged on the auxiliary blade A and the main blade D2.

3. The dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan according to claim 2, characterized in that: The bottom of the auxiliary blade A is connected to the profile compensation block B via a rotating seat (3-2), the profile compensation block B is slidably connected to the limiting sliding groove (3-1), and the profile compensation block C is connected to the top of the main blade D2 via a rotating seat (3-2).

4. The dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan according to claim 1, characterized in that: The trailing edge height of the profile compensation block B and the profile compensation block C is 20% of the height of the main blade D2, which is used to avoid the inability to effectively perform area compensation when the main and auxiliary blades are adjusted at a large angle due to the area compensation block being too small.

5. The dual-angle adjustable inlet guide vane for widening the stability margin of an adaptive fan according to claim 1, characterized in that: The dividing point between the leading edge of the main blade D2 and the auxiliary blade A is the height corresponding to point a, and point a is the lowest height of the separation zone of the fan in a high bypass ratio state.

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