Seesaw and control method for flow regulation of wide Mach number aircraft

Abstract

The present invention discloses a seesaw for flow regulation of wide Mach number aircraft and a control method, belonging to the field of aircraft design and aerodynamics, wherein the seesaw comprises: a double seesaw arranged between the inlet section and the outlet section of the air inlet and having the same width as the air inlet, wherein the double seesaw comprises: a first-stage seesaw arranged at the tail end of the inlet section and rotatably connected to the tail end of the inlet section through a rotating shaft I; a second-stage seesaw arranged at the tail end of the first-stage seesaw and rotatably connected to the tail end of the inlet section through a rotating shaft II; wherein the first-stage seesaw and the second-stage seesaw can both rotate toward the outside of the flow channel with the cooperation of the corresponding rotating shafts. The present invention provides a seesaw for flow regulation of wide Mach number aircraft and a local deformation control method, which can be used in the scene of regulating the air inlet in a wide speed range and a large airspace, realizing effective regulation of the air inlet flow and optimization of the local flow field under wide Mach number conditions, and having the advantages of simple structure and easy implementation.

Description

Technical Field

[0001] The present invention relates to the field of aircraft design and aerodynamics, and more particularly to a seesaw and a control method for flow regulation of wide Mach number aircraft. Background Art

[0002] Flying in a wide speed range and large airspace is an inevitable trend in the development of the next generation of hypersonic aircraft. Reusable hypersonic aircraft flying in dense atmosphere and near space are new aircraft that will lead the aerospace technology revolution and create a new pattern of aerospace integration development in the future. The air intake of a wide range aircraft is the inlet and channel for the air required by the engine, and is the core component for capturing and transporting the air required by the air-breathing engine. Flow matching is that the air intake must ensure that the air flow required by the engine can be provided at any point in the flight envelope, meet the working conditions of mass conservation and flow continuity, and achieve the highest possible total pressure recovery coefficient and low energy loss. Wide range aircraft span subsonic, supersonic and higher flight speeds, with a large flight envelope and significant changes in aerodynamic and propulsion characteristics. In response to the working requirements of a wide speed range and a wide space domain, the aircraft air intake supplies the amount of air required by the engine and ensures the stable operation of the air intake under various flight conditions and engine working conditions. For example, under low flight Mach number conditions, the air density is high, the flight resistance is relatively greater, and the required air flow is greater than that of high altitude and high Mach number flight. Therefore, traditional fixed-geometry inlets are difficult to meet the wide flow requirements of hypersonic aircraft in a wide speed range and large airspace. It is necessary to adjust the inlet geometry to achieve flow regulation and local flow state for wide-range aircraft, so that the aircraft has higher flight efficiency in all flight stages, realize safe and stable flight of the aircraft in a wide speed range and wide airspace, and broaden the engine starting performance. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these objects and other advantages of the present invention, a seesaw for flow control of a wide Mach number aircraft is provided, comprising: a double seesaw disposed between an inlet section and an outlet section of an inlet duct and having the same width as the inlet duct, the double seesaw comprising:

[0005] A first-stage seesaw disposed at the tail end of the inlet section and rotatably connected to the tail end of the inlet section via a rotating shaft I;

[0006] A second stage seesaw is arranged at the tail end of the first stage seesaw and is rotatably connected to the tail end of the inlet section via a rotating shaft II;

[0007] Wherein, the first-stage seesaw and the second-stage seesaw can both rotate toward the outside of the flow channel with the cooperation of the corresponding rotating shaft.

[0008] Preferably, the turning circle section of the air inlet is the design area of ​​the second stage seesaw, and the length of the second stage seesaw is configured to be 1 to 3 times the thickness of the local boundary layer;

[0009] The dependent domain of the vehicle forebody shock wave is a constraint condition for the design of the first-stage seesaw.

[0010] A seesaw control method is based on the seesaw control to achieve aircraft flow regulation under a wide Mach number, comprising:

[0011] When the flight Mach number of the aircraft is lower than the aerodynamic design Mach number, the second stage seesaw is kept at 0°, and the flow rate is adjusted by rotating the first stage seesaw. The greater the flight Mach number deviates from the design Mach number of the inlet, the greater the rotation angle of the first stage seesaw.

[0012] When the flight Mach number is higher than the design Mach number, the first-stage seesaw is kept at 0°, and the local flow field is adjusted by rotating the second-stage seesaw.

[0013] The present invention includes at least the following beneficial effects: the present invention is a seesaw structure for adjusting an inlet duct in a wide speed range and a large airspace. In the process of controlling the local deformation of the seesaw, different control schemes are designed for two situations where the flight Mach number is lower than and higher than the design Mach number of the inlet duct, respectively, thereby achieving effective regulation of the inlet duct flow and optimization of the local flow field under wide Mach number conditions, and having the advantages of simple structure and easy implementation.

[0014] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a three-dimensional inward-rotating air intake duct-isolation section structure constructed by an air intake duct and a double rocker structure in one embodiment of the present invention;

[0016] Figure 2 for Figure 1 Schematic diagram from another perspective;

[0017] Figure 3 Schematic diagram of the flow field structure of the inlet duct-isolation section when the Mach number is 2 and the first-stage seesaw rotates 10° in Example 1 of the present invention (Mach number distribution cloud diagram);

[0018] Figure 4 Schematic diagram of the flow field structure of the inlet duct-isolation section when the Mach number is 4 and the first-stage seesaw rotates 4° in Example 2 of the present invention (Mach number distribution cloud diagram);

[0019] Figure 5Schematic diagram of the flow field structure of the inlet duct-isolation section when the Mach number is 4 and the first-stage seesaw rotates 6° in Example 2 of the present invention (Mach number distribution cloud diagram);

[0020] Figure 6 Schematic diagram of the flow field structure of the inlet duct-isolation section when the Mach number is 8 and the first-stage seesaw rotates 6° in Example 3 of the present invention (Mach number distribution cloud diagram);

[0021] Among them, the first-stage seesaw-4, the second-stage seesaw-6, the rotating shaft I-3, the rotating shaft II-5, the inlet section-1, the outlet section-6, the inlet-7, and the outlet-8. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0023] According to the aerodynamic, power, loading capacity and other requirements of hypersonic aircraft in a wide speed range and large airspace, after the design of the air inlet matching the front body of the aircraft is completed, the air inlet can usually be in good working performance under the design state of a single flight Mach number, but under non-design flight conditions, the capture capability and intake quality of the air inlet are greatly reduced.

[0024] In view of such problems, the purpose of the present invention is to design a local adjustment method for a three-dimensional inward-rotating inlet suitable for a wide-range air-breathing high-speed aircraft to meet the requirements of a wide air intake flow rate and local complex flow, which mainly includes the following steps:

[0025] 1. Intake duct double rocker deformation method

[0026] by Figure 1This method is introduced by taking the inward-inward three-dimensional inlet-isolator configuration as an example. The inlet-isolator configuration is 1990 mm long and has a design Mach number of 6. When the inlet flow is below the design Mach number (Mach number 2-4), the inlet flow capture is poor and the working efficiency is low. In this regard, a double rocker control method is designed in the second half of the inlet. On the one hand, the aircraft forms one or more forebody shock waves during flight. Based on the basic principle of the characteristic line method, the characteristic line coverage area emitted from each point on the forebody shock wave is the dependency domain of the forebody shock wave. If the aircraft wall configuration in the dependency domain is modified, it will in turn affect the shape, strength and other parameters of the forebody shock wave. Therefore, when designing a local geometric deformation scheme for the inlet, the inlet wall configuration in the forebody shock wave dependency domain cannot be changed to avoid affecting the shape and strength of the forebody shock wave, thereby changing the performance of the inlet and the overall performance of the aircraft. On the other hand, when designing the local geometric deformation scheme of the air inlet, multiple factors such as the volume of the aircraft body, the demand for air by the combustion organization of the combustion chamber, and the three-dimensional geometric feature restrictions of the air inlet should be considered at the same time to achieve a better adjustment effect. In this method, the dependent domain of the shock wave of the aircraft forebody is used as the constraint condition for the design of the front end of the seesaw, and the turning section of the air inlet is used as the end of the seesaw design area.

[0027] Based on this principle, a seesaw structure is designed at the end of the shock wave dependent domain of the forebody of the aircraft (see Figure 1-Figure 2 ), the seesaw is the same width as the air inlet, and includes two levels of seesaws. The first-level seesaw 4 can rotate around the rotation axis Ⅰ3 to the outside of the flow channel. The second-level seesaw 6 is designed at the end of the first-level seesaw. Based on the results of numerical calculation and analysis, it can be seen that the length of the second-level seesaw should be 1 to 3 times the thickness of the local boundary layer. The second-level seesaw can rotate around the rotation axis Ⅱ5 to the outside of the flow channel. The second-level seesaw 6 is located between the inlet section 1 and the outlet section 6 of the air inlet, and the first-level seesaw 4 and the second-level seesaw 6 do not affect the smoothness of the gas channel constructed by the inlet 7 and the outlet 8 in the air inlet.

[0028] 2. Local deformation control method of double rocker

[0029] When the flight Mach number of the aircraft is lower than its aerodynamic design Mach number, flow regulation is achieved by rotating the first-stage seesaw, and the second-stage seesaw is kept at 0°. The greater the flight Mach number deviates from the design Mach number of the inlet, the greater the rotation angle of the first-stage seesaw, and the better the regulation effect on the total pressure recovery performance and flow field structure of the inlet. However, at the same time, the demand for oxidant by the combustion organization in the aircraft combustion chamber must be taken into account in combination with actual conditions.

[0030] When the flight Mach number is higher than the design Mach number, the inlet is in an over-rated state. At this time, the first-stage seesaw is kept at 0°, and the local flow field is adjusted by rotating the second-stage seesaw.

[0031] 3. Embodiment

[0032] The flight Mach numbers of 2, 4, and 8 are taken as the typical flight states of the wide-range aircraft. By applying the geometric deformation scheme of the inlet in the present invention, the flow field start-up of Mach numbers 2 and 4 and the local optimization target of the flow field of Mach number 8 are achieved respectively. The parameters of the typical flight trajectory point are shown in Table 1 (Table 1 is the calculation condition setting of the rotary inlet in the range of Mach numbers 2-6).

[0033] Table 1

[0034]

[0035] Embodiment 1:

[0036] Under the flight Mach number 2 condition, when the inward-turning inlet does not perform geometric deformation control, the inlet deviates seriously from the design point and is in a non-startup state. As the first-stage seesaw rotates, the scale of the flow separation zone on the shoulder of the inlet gradually decreases, the intensity of the separation shock wave gradually weakens, and the total pressure recovery coefficient of the inlet increases. At the same time, due to the increase in overflow flow at the seesaw, the flow coefficient of the inlet does not change monotonically. The performance and parameters of the inward-turning inlet under different first-stage seesaw angles are shown in Table 2. When the seesaw angle is 10°, the total pressure recovery coefficient and the flow coefficient both reach a relatively ideal state. The flow field Mach number distribution at this time is shown in Table 2. Figure 2 .

[0037] Table 2

[0038]

[0039] Embodiment 2:

[0040] Under the condition of flight Mach number 4, when the inward-turning inlet does not perform geometric deformation control, the inlet remains in an inactive state. As the rotation angle of the first-stage seesaw increases, the flow separation formed at the shoulder of the inlet gradually weakens. Both the outlet flow coefficient and the total pressure recovery coefficient first increase and then decrease with the increase of the rotation angle. With the excessive increase of the seesaw angle, more air flows out from the overflow port, causing the overall performance of the inlet to deteriorate. The performance and parameters of the inward-turning inlet under different first-stage seesaw angles at Mach number 4 are shown in Table 3. When the seesaw angle is 4°, the inlet outlet flow coefficient reaches the maximum, which is 0.6920; when the seesaw rotates to 6°, the inlet total pressure recovery coefficient reaches the maximum, which is 0.8726. The specific scheme can be selected between 4° and 6° according to actual needs. See the flow field Mach number distribution. Figure 3 .

[0041] Table 3

[0042] Embodiment 3:

[0043] When the flight Mach number is greater than the design Mach number of the aircraft, the external compression wave system enters the compression channel inside the inlet, and the inlet is in an overrated state. There is no need to rotate the first-stage seesaw for macro-adjustment of the inlet flow, only the second-stage seesaw needs to be rotated for local adjustment. Under the flight Mach number of 8, as the rotation angle of the second-stage seesaw increases, the inlet outlet flow coefficient gradually decreases, and the throat total pressure recovery coefficient gradually increases, but the increase is slow. The results are shown in Table 4 (Table 4 shows the performance and parameters of the internal rotating inlet under different second-stage seesaw angles). When the second-stage seesaw rotates 6°, the total pressure recovery coefficient is as high as 0.2914, which meets the performance indicators. The flow field Mach number distribution is shown in Table 4. Figure 4 .

[0044] Table 4

[0045]

[0046] From the above examples, it can be seen that the low-speed area near the seesaw is effectively controlled and the flow quality of the coupled flow field inside and outside the inlet is significantly improved.

[0047] The above solution is only an illustration of a preferred embodiment, but is not limited thereto. When implementing the present invention, appropriate replacement and / or modification can be performed according to user needs.

[0048] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A seesaw for flow control of wide Mach number aircraft, characterized in that: include: A double rocker plate is arranged between the inlet section and the outlet section of the air inlet duct and has the same width as the air inlet duct, and the double rocker plate comprises: A first-stage seesaw disposed at the tail end of the inlet section and rotatably connected to the tail end of the inlet section via a rotating shaft I; A second stage seesaw is arranged at the tail end of the first stage seesaw and is rotatably connected to the tail end of the inlet section via a rotating shaft II; Wherein, the first-stage seesaw and the second-stage seesaw can both rotate toward the outside of the flow channel under the cooperation of the corresponding rotating shaft; The turning circle section of the inlet duct is the design area of ​​the second-stage seesaw, and the length of the second-stage seesaw is configured to be 1 to 3 times the thickness of the local boundary layer; The dependent domain of the forebody shock wave of the aircraft is the constraint condition for the design of the first stage seesaw; A method for achieving aircraft flow regulation at a wide Mach number by controlling a seesaw, comprising: When the flight Mach number of the aircraft is lower than the aerodynamic design Mach number, the second stage seesaw is kept at 0°, and the flow rate is adjusted by rotating the first stage seesaw. The greater the flight Mach number deviates from the design Mach number of the inlet, the greater the rotation angle of the first stage seesaw. When the flight Mach number is higher than the design Mach number, the first-stage seesaw is kept at 0°, and the local flow field is adjusted by rotating the second-stage seesaw.

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