Double-adjusting-angle inlet-adjustable guide vane for widening bypass ratio working range of fan

Abstract

The invention provides a double-adjusting-angle inlet-adjustable guide vane for widening the bypass ratio working range of a fan, which comprises a first main vane, a second main vane, an auxiliary vane, a main shaft A and an auxiliary shaft B. One side of the first main vane is provided with the second main vane and the auxiliary vane, and the auxiliary vane is positioned below the bottom of the second main vane. The main shaft A is arranged at the blade bottom of the first main blade, and the auxiliary shaft B is arranged at the blade bottom of the auxiliary blade and located in the hollow cylinder of the main shaft A. The main shaft A is used for driving the first main blade and the second main blade to rotate. The auxiliary shaft B is used for driving the auxiliary blade to rotate. The first main blade, the second main blade and the auxiliary blade are adjusted through the main shaft A and the auxiliary shaft B, the flow field of an inlet of the fan is adjusted in a partitioned mode, pre-rotation of different degrees is provided for inlet airflow with different blade heights of the fan, the quality of the inlet airflow of the fan is improved, the working efficiency of self-adaptive starting is improved, and the bypass ratio change range of the self-adaptive fan is widened.

Description

Technical Field

[0001] The present invention belongs to the technical field, and in particular relates to a double-adjustable-angle inlet adjustable guide vane for widening the operating range of a fan bypass ratio. 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, the adaptive engine technology has been demonstrated by domestic and foreign researchers, and they all pointed out that the adaptive fan component is one of the key technologies to achieve its comprehensive performance. In addition to completing the supercharging effect of the traditional fan, it must also complete the flow regulation and variable bypass ratio functions unique to the adaptive variable cycle engine, 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 the adaptive fan are strict, and it is difficult to meet the 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 condition (small bypass ratio condition) to the large bypass ratio 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 design a full three-dimensional adjustable guide vane technology based on dual adjustment angles to change the blade profile to achieve partition control in view of the complex radial changes in the internal flow field when the adaptive fan is converted from a small bypass ratio condition to a large bypass ratio condition, so as to significantly improve the combat capability of the adaptive variable cycle engine, and provide a dual adjustment angle inlet adjustable guide vane for widening the fan bypass ratio working range;

[0012] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a double-adjustable angle inlet adjustable guide vane for widening the working range of the fan bypass ratio, comprising: a first main blade, a second main blade, an auxiliary blade, a main shaft A and an auxiliary shaft B;

[0013] A second main blade and an auxiliary blade are respectively arranged on one side of the first main blade, the auxiliary blade is located below the bottom of the second main blade and contacts the arc-shaped groove on the first main blade, the main axis A is arranged on the bottom of the first main blade, and the auxiliary axis B is arranged on the bottom of the auxiliary blade and is located in the hollow cylinder of the main axis A;

[0014] The main shaft A is used to drive the first main blade and the second main blade to rotate, and the secondary shaft B is used to drive the secondary blade to rotate.

[0015] Furthermore, the first main blade and the second main blade are connected as a whole via a trapezoidal keyway.

[0016] Furthermore, the height of the intersection of the trailing edges of the second main blade and the auxiliary blade is the height corresponding to the dividing point where the fan rotor inlet airflow angle changes greatly and relatively less.

[0017] Furthermore, the leading edge of the auxiliary blade is located at 35%-45% of the chord length of the entire fan blade base.

[0018] Furthermore, a quarter radius portion at one end of the main axis A is connected to the bottom of the first main blade, and another three quarter radius portion is in contact with the bottom of the auxiliary blade.

[0019] Furthermore, the secondary axis B is located at the leading edge of the secondary blade, and the perpendicular line to the center of the inscribed circle of the blade profile at this position is the secondary axis B.

[0020] Furthermore, the main axis A takes the middle arc line of the initial blade profile as a reference point, and the adjustment range of rotation around the rotation axis is -20° to 20°.

[0021] Furthermore, the secondary axis B takes the middle arc line of the initial blade profile as a reference point, and the adjustment range of rotation around the rotation axis is -30° to 30°.

[0022] Beneficial effects: The present invention inherits the advantages of traditional adjustable guide vanes while being able to adjust the flow field at the fan inlet in different zones, providing different degrees of pre-swirl for the fan inlet airflow at different blade heights, improving the quality of the fan inlet airflow, improving the working efficiency of the adaptive engine, and increasing the bypass ratio variation range of the adaptive fan, thereby providing a wider working range for the variable cycle engine and significantly improving the combat capability of the variable cycle engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 It is a three-dimensional structural schematic diagram of the double-adjustable-angle inlet adjustable guide vanes for widening the operating range of the fan bypass ratio.

[0024] Attached Figure 2 It is a dual-adjustable angle inlet adjustable guide vane meridian pattern that widens the fan bypass ratio operating range.

[0025] Attached Figure 3 It is a relationship diagram between the fan blade inlet angle parameters and the speed triangle.

[0026] Attached Figure 4 It is a schematic diagram of the radial distribution of the inlet airflow angle of the fan under small bypass ratio and large bypass ratio conditions.

[0027] Attached Figure 5 It is a schematic diagram of the change in the blade profile of the small blade height section by adjusting the secondary shaft rotation angle with the double-adjustable inlet guide vane.

[0028] Attached Figure 6 It is a schematic diagram of the change in blade profile of large blade height section with double adjustable angle inlet adjustable guide vanes to adjust the main shaft rotation angle.

[0029] Attached Figure 7 It is a schematic diagram of the change in the blade profile of the large and small blades with double-adjustable angle inlet adjustable guide vanes to adjust the rotation angles of the main shaft and the secondary shaft. DETAILED DESCRIPTION

[0030] The present invention will be further explained below in conjunction with the accompanying drawings.

[0031] In the design state of minimum bypass ratio under fixed flow, the inlet adjustable guide vane maintains the initial blade shape, and the guide vane is not adjusted or slightly changed. The airflow entering the fan can flow along the blade profile and decelerate and increase pressure well, and the airflow has almost no flow separation on the suction surface of the blade. When the bypass ratio of the fan increases, the throttling degree of the inner channel increases, and the flow of the inner channel decreases, resulting in a decrease in the flow of the fan blade bottom part corresponding to the inner channel, so that the inlet angle of attack increases, and a larger low-speed area appears at the trailing edge of the fan blade height rotor; therefore, the inlet adjustable guide vane is required to provide the fan with a suitable airflow pre-swirl, that is, to provide a suitable angle of attack for the fan inlet airflow to reduce the range of the low-speed area; at the same time, it is also necessary to adjust the blade center and blade tip, because when changing to a larger bypass ratio, the strong throttling of the inner channel will also affect the throttling effect of the large blade height outer duct, resulting in a relative decrease in the fan large blade height flow, so the airflow attack angle at the inlet of the fan blade tip is relatively increased, but the change is smaller than that in the blade root area, so the inlet adjustable guide vane is required to adjust the airflow pre-swirl in the large blade height area to provide a suitable angle of attack for the airflow at the blade tip part.

[0032] Based on the above research, Figure 1 As shown, the present invention provides a double-adjustable angle inlet adjustable guide vane for widening the operating range of the fan bypass ratio, comprising: a first main blade 1, a second main blade 2, an auxiliary blade 3, a main shaft A and an auxiliary shaft B.

[0033] A second main blade 2 and an auxiliary blade 3 are respectively arranged on one side of the first main blade 1. The auxiliary blade 3 is located below the bottom of the second main blade 2 and is in contact with the arc-shaped groove on the first main blade 1. The main axis A is arranged on the bottom of the first main blade 1, and the auxiliary axis B is arranged on the bottom of the auxiliary blade 3 and is located in the hollow cylinder of the main axis A.

[0034] The main shaft A is used to drive the first main blade 1 and the second main blade 2 to rotate, and the secondary shaft B is used to drive the secondary blade 3 to rotate.

[0035] In the above scheme, the first main blade 1 and the second main blade 2 are driven to rotate by rotating the main shaft A to provide a suitable angle of attack for the fan inlet to eliminate the flow separation within the tip range of the fan blade, and the auxiliary blade 3 is driven to rotate by rotating the secondary shaft B to reduce the angle of attack of the fan inlet airflow, so that the airflow flows along the back of the blade as much as possible, reducing the low-speed area of ​​the trailing edge.

[0036] like Figure 3 As shown, the angle of attack in the fan inlet velocity triangle is i = β k-β, too large an angle of attack will cause the airflow in the fan to no longer flow along the blade surface, and the airflow will produce a large flow separation at the back of the fan rotor blade, causing a large flow blockage and flow loss in the blade channel. Therefore, the relative airflow angle at the fan inlet can be reduced to reduce the inlet angle of attack, thereby reducing the flow separation at the back of the fan rotor blade, thereby widening the fan's surge boundary. Therefore, the basic theory in the design of the inlet adjustable guide vane is to apply different degrees of inlet pre-swirl according to the fan inlet velocity triangle to improve the airflow flow.

[0037] Based on the above basic theory, the design idea of ​​this scheme is to add an adjustable secondary axis B on the basis of the original single-angle adjustable inlet guide vane profile. The blades are divided into main blades and secondary blades 3 along the secondary axis, which can apply different degrees of pre-rotation to different blade heights.

[0038] The main blades include a first main blade 1 and a second main blade 2. The first main blade 1 and the second main blade 2 are connected as a whole through a trapezoidal keyway, so as to facilitate the overall assembly.

[0039] The main shaft A is a hollow cylindrical rotating shaft. A quarter of the radius part at one end of the main shaft A is connected to the bottom of the first main blade 1 as a whole, and the other three quarters of the radius part is in contact with the bottom of the auxiliary blade 3. The auxiliary shaft B is located in the hollow cylinder of the main shaft A, and the auxiliary shaft B is located at the perpendicular line of the center of the inscribed circle of the leading edge blade of the auxiliary blade 3, and is connected to the bottom of the auxiliary blade 3 as a whole. This main and auxiliary shaft layout can effectively reduce the interference between the actuating mechanisms.

[0040] The main shaft A is also connected to the main blade rocker arm, and the secondary shaft B is also connected to the secondary blade rocker arm, and the main blade rocker arm and the secondary blade rocker arm are respectively connected to the corresponding drive ring through joint bearings. Under the action of the drive ring, the main blade rocker arm can drive the main shaft A to rotate, and the secondary blade rocker arm can drive the secondary shaft B to rotate. In order to solve the problem that when the working condition is converted from a small bypass ratio to a large bypass ratio, the throttling intensity of the inner duct of the fan is enhanced, resulting in a large change in the inlet airflow angle at the height of the fan blade, the main shaft A takes the middle arc line of the initial blade shape as the reference point, and the adjustment range of rotation around the rotating axis is -20°—20°. The secondary shaft B takes the middle arc line of the initial blade shape as the reference point, and the adjustment range of rotation around the rotating axis is -30°—30°, so as to increase the upper limit of the fan bypass ratio.

[0041] The adjustment process involves two-stage adjustment of the main blade and the auxiliary blade 3. Too complex three-dimensional blade shape will increase the difficulty of guide vane adjustment. In order to make the adjustment mechanism simpler and more efficient, the initial blade shape of the double-adjustment angle inlet guide vane will adopt an axisymmetric initial three-dimensional blade shape without bend or sweep. This blade shape has a simple configuration and can better play a rectifying role.

[0042] like Figure 2 and Figure 4As shown, when the variable cycle fan changes from a fixed flow rate and a small bypass ratio design state to a large bypass ratio state, the relative airflow angle at the rotor inlet changes in a radial direction with inconsistent amplitude, which results in that the preselection degree applied by the inlet guide vane to the fan in order to expand the range of change of the fan bypass ratio is inconsistent along the radial direction; for this reason, when the fan is converted from a fixed flow rate and a small bypass ratio design state to a large bypass ratio, the degree of throttling in the fan inner duct is enhanced, and the airflow angle at the high inlet of the fan rotor blade will change more. Point a is the dividing point where the fan rotor inlet airflow angle changes greatly and relatively less. The dividing point is determined by making flexible treatment according to the inlet airflow conditions of different fan rotors. Therefore, after determining the initial blade shape, the area of ​​the main blade and the auxiliary blade 3 is divided. The specific division method is: the height corresponding to point a is taken as the intersection height of the main blade and the auxiliary blade at the trailing edge of the guide vane, that is, a to the blade top b is the main blade, a to the blade root c is the auxiliary blade 3, and in order to enhance the control ability of the guide vane over the airflow, the leading edge of the auxiliary blade 3 is located at 35%-45% of the chord length of the fan blade.

[0043] like Figure 5-6 As shown, the guide vane adjustment angles required at the blade root and blade tip of the fan rotor are shown when the fan is converted from a fixed flow and small bypass ratio design state to a large bypass ratio.

[0044] like Figure 7 A comprehensive adjustment method for the dual-angle adjustable inlet guide vanes to coordinate the adjustment angles of different blade heights.

[0045] Example 1

[0046] For a variable circulation fan with a bypass ratio ranging from 0.07 to 0.9, the performance requirements are that the fan design point efficiency is not less than 86% at any bypass ratio, the pressure ratio is not less than 1.7, and the stability margin reduction value is not higher than 8%. When the variable cycle fan is in the state of bypass ratio 0.07 (small bypass ratio turbofan engine), there is only a small range of flow separation in the middle and tip of the blade during the throttling process. The degree of pre-rotation applied to the main blade can be adjusted by adjusting the main shaft A to eliminate or reduce the flow separation at the tip and middle of the blade, thereby expanding the stability margin of the fan at this bypass ratio. Gradually increasing the bypass ratio of the variable cycle fan, the relative airflow angle at the fan inlet varies in an inconsistent radial direction, the relative airflow angle at the tip changes less, while the relative airflow angle at the root changes more. Therefore, when the variable cycle fan is in the state of bypass ratio 0.9, the relative airflow angle at the tip and middle of the blade changes less, and the flow field at the tip and middle of the blade can be adjusted by slightly adjusting the main shaft A, while the relative airflow angle at the root changes relatively more, and the flow field at the root can be adjusted by adjusting the secondary shaft B. The two shaft adjustments cooperate with each other to improve the quality of the inlet airflow, which can not only achieve the purpose of expanding stability, but also achieve the purpose of expanding the fan bypass ratio range by improving the flow field, thereby improving the combat capability of the variable cycle engine. In the bypass ratio mode of 0.07-0.9, the secondary shaft controls the secondary blades to adjust the angle according to the regulation requirements of the high inlet flow field of the downstream rotor small blades, and the main shaft controls the main blades to adjust the high inlet flow field of the downstream rotor large blades. By coordinating the adjustment of the two shafts, the fan design point efficiency is maintained at 87.8%-90.2%, the compression ratio is as high as 1.81-1.93, and the stability margin reduction value is less than 6.8%.

[0047] When the fan is switched from a small bypass ratio condition to a large bypass ratio condition, the present invention coordinately adjusts the main shaft A and the secondary shaft B to adjust the first main blade 1, the second main blade 2 and the secondary blade 3, thereby realizing zoned adjustment of the flow field at the fan inlet, providing different degrees of pre-rotation for the fan inlet airflow with different blade heights, improving the quality of the fan inlet airflow, improving the working efficiency of the adaptive engine fan, and increasing the bypass ratio variation range of the adaptive fan, providing a wider working range for the variable cycle engine, and significantly improving the combat capability of the adaptive engine.

[0048] 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-adjustable inlet guide vanes for widening the operating range of fan bypass ratio, characterized in that: include: A first main blade (1), a second main blade (2), a secondary blade (3), a main axis A and a secondary axis B; A second main blade (2) and an auxiliary blade (3) are respectively arranged on one side of the first main blade (1); the auxiliary blade (3) is located below the bottom of the second main blade (2) and is in contact with the arc-shaped groove on the first main blade (1); the main axis A is arranged on the bottom of the first main blade (1); the auxiliary axis B is arranged on the bottom of the auxiliary blade (3) and is located in the hollow cylinder of the main axis A; The main shaft A is used to drive the first main blade (1) and the second main blade (2) to rotate, and the secondary shaft B is used to drive the secondary blade (3) to rotate.

2. The double-adjustable inlet guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: The first main blade (1) and the second main blade (2) are connected as a whole via a trapezoidal keyway.

3. The double-adjustable inlet guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: The height of the intersection of the trailing edges of the second main blade (2) and the auxiliary blade (3) is the height corresponding to the dividing point where the fan rotor inlet airflow angle changes greatly and relatively less.

4. The double-adjustable inlet guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: The leading edge of the auxiliary blade (3) is located at 35%-45% of the chord length of the entire fan blade base.

5. The double-adjustable inlet guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: A quarter radius portion at one end of the main axis A is connected to the bottom of the first main blade (1), and another three quarter radius portion is in contact with the bottom of the auxiliary blade (3).

6. The double-adjustable inlet guide vane for widening the fan bypass ratio operating range according to claim 1, characterized in that: The secondary axis B is located at the leading edge of the secondary blade, and the perpendicular line to the center of the inscribed circle of the blade at this position is the secondary axis B.

7. The double-adjustable inlet adjustable guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: The main axis A takes the middle arc line of the initial blade profile as the reference point, and the adjustment range of rotation around the rotation axis is -20° to 20°.

8. The double-adjustable inlet guide vane for widening the operating range of the fan bypass ratio according to claim 1, characterized in that: The secondary axis B takes the middle arc line of the initial blade profile as a reference point, and the adjustment range of rotation around the rotation axis is -30° to 30°.

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