Hypersonic inlet and adaptive surge control method

Abstract

The application discloses a hypersonic inlet and a self-adaptive surge control method, wherein a leakage port and a pressure injection port are arranged on the lower wall of the inlet, and a movable slider with a spring is arranged on a slide rail to realize self-adaptive surge control of the inlet. When the pressure downstream of the hypersonic inlet increases, the terminal shock wave is transmitted forward, the high pressure of the shock wave train drives the movable slider to move forward, the leakage cavity on the lower wall of the inlet is opened, and the terminal shock wave is stopped at the inlet of the leakage cavity when the terminal shock wave is transmitted to the inlet, so that the forebody wave system of the inlet is not damaged, and the inlet always keeps in a starting state; when the back pressure downstream of the inlet decreases, the terminal shock wave is withdrawn, the movable slider is withdrawn under the action of the spring, and the leakage cavity is closed, so that the flow of the inlet is not affected. Therefore, the self-adaptive surge control method can improve the anti-back pressure capacity of the inlet, widen the surge margin of the inlet, and ensure the flow characteristics of the inlet when the flow field of the inlet is stable.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft aerodynamics, and particularly relates to a hypersonic inlet. BACKGROUND

[0002] The scramjet engine mainly consists of four parts: hypersonic inlet, isolator, combustion chamber and nozzle. The hypersonic inlet, as one of the important components of the scramjet engine, is responsible for providing sufficient high-pressure gas for the downstream combustion chamber, and its aerodynamic performance will directly affect the overall performance of the entire propulsion system.

[0003] When the back pressure at the outlet of the inlet exceeds a certain critical value, the inlet will lose stability from the stable working state and trigger surge, entering the unstart state, causing the thrust of the entire propulsion system to decrease rapidly, and even damaging the structure of the entire propulsion system. Therefore, the inlet should be avoided from entering the unstart state as much as possible, or the surge intensity of the inlet should be reduced. The commonly used control method is bleed control, which releases air through the lower wall or upper wall of the inlet to improve the anti-back pressure capability of the inlet and widen the surge margin of the inlet.

[0004] However, the current bleed method is mostly fixed geometry, that is, there is always a flow loss, and it cannot adjust itself according to the change of the back pressure at the outlet of the inlet. Even if the terminal shock wave does not cross the throat, the inlet will still have a flow loss. Therefore, a new technical solution is needed to solve the above problems. SUMMARY

[0005] In order to solve the problems of the prior art, the present application provides a hypersonic inlet, which aims to realize surge control of the inlet, improve the surge margin, and have no mass flow loss when the terminal shock wave does not cross the throat of the inlet.

[0006] The present application also provides an adaptive surge control method for the above-mentioned hypersonic inlet.

[0007] To achieve the above-mentioned purposes, the technical scheme adopted by the hypersonic inlet of the present application is as follows:

[0008] The application relates to a hypersonic inlet, which comprises an inlet lower wall, a lip cover located at the periphery of the inlet lower wall, and an inlet inner channel formed between the inlet lower wall and the lip cover, characterized in that a leakage cavity is arranged in the inlet lower wall, an injection cavity is arranged behind the leakage cavity, an injection channel is arranged between the injection cavity and the leakage cavity, a piston is arranged in the injection channel, a baffle, a sliding block, a spring, a sliding rail for the sliding block are further arranged in the inlet lower wall, the baffle and the injection channel are respectively located on the two sides of the leakage cavity, one end of the spring is connected with the baffle and the other end is connected with the sliding block, one end of the sliding block is connected with the spring and the other end is connected with the piston through a connecting rod, the leakage cavity and the injection cavity are communicated with the inlet inner channel, when the spring is in a free state, the sliding block is located below the leakage cavity and seals the leakage cavity, when the piston moves towards the baffle, the piston drives the sliding block to move away from below the leakage cavity to open the leakage cavity, and the spring is compressed.

[0009] Further, the leakage cavity is located at an upstream position of a reflection point of an incident shock wave of the lip cover, and the injection cavity is located at a downstream position of the reflection point of the incident shock wave.

[0010] Further, the spring stiffness coefficient is less than 1000 N / m.

[0011] Further, the inlet lower wall is provided with a plurality of parallel leakage slots, the leakage slots are located above the leakage cavity and are communicated with the leakage cavity.

[0012] Further, the inlet lower wall is provided with a plurality of parallel injection slots, the injection slots are located above the injection cavity and are communicated with the injection cavity.

[0013] Further, the inlet lower wall is provided with a containing cavity for surrounding the sliding block, the containing cavity is coaxially arranged with the injection channel and is respectively located on the two sides of the leakage cavity, a sliding rail for the sliding block to slide is arranged at the bottom of the containing cavity, when the sliding block moves away from below the leakage cavity to open the leakage cavity, the sliding block enters the containing cavity.

[0014] Further, the inlet height h is determined according to design requirements, the leakage slot width 0.125h<=l1<=0.16h, the injection hole width l2

[0015] Beneficial effects: the leakage and injection openings are arranged on the inlet lower wall, and the moving sliding block with the spring is arranged in the sliding rail to automatically adjust the leakage flow, thereby improving the anti-back pressure capacity of the inlet and widening the surge margin of the inlet. When the terminal shock wave is located at a downstream position of the throat, the leakage disappears and no flow loss occurs.

[0016] The application also provides the technical scheme of the adaptive surge control method of the above high supersonic inlet: when the counter pressure of the downstream of the inlet increases and the trailing shock wave is transmitted forward, the high pressure in the trailing shock wave string drives the moving slider to move forward, the bleed cavity of the inlet is opened, and the trailing shock wave of the downstream is stabilized. When the counter pressure of the downstream of the inlet decreases, the trailing shock wave retreats, and the moving slider retreats under the action of the spring, without affecting the flow of the inlet.

[0017] Further, when the trailing shock wave string of the downstream of the inlet is not transmitted forward to the throat, the spring force just makes the moving slider completely block the bleed cavity, and at this time, the mass flow loss of the inlet is zero.

[0018] Further, when the bleed cavity of the lower wall of the inlet is opened, the trailing shock wave is stopped at the inlet of the bleed cavity when the trailing shock wave is transmitted forward to the inlet of the bleed cavity, and the inlet always maintains the starting state. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Fig. 1 is a structural schematic diagram of a high supersonic inlet provided by the application, and shows the state when the bleed cavity is closed.

[0020] Figure 2 Fig. 2 is a structural schematic diagram of a high supersonic inlet provided by the application, and shows the state when the bleed cavity is opened.

[0021] Figure 3 Fig. 3 is a size schematic diagram of a high supersonic inlet.

[0022] Figure 4 Fig. 4 is a schematic diagram of a blocking cone.

[0023] Figure 5 Fig. 5 is a curve diagram of the inlet flow rate changing with time.

[0024] Figure 6 Fig. 6 is a Mach cloud diagram of the control configuration when the bleed is closed and opened, wherein Figure 6 (a) is a Mach cloud diagram in the closed state of the bleed cavity, Figure 6 (b) is a Mach cloud diagram in the opened state of the bleed cavity. DETAILED DESCRIPTION

[0025] The application will be further illustrated below in combination with the drawings and specific embodiments, and it should be understood that the following specific embodiments are only used to illustrate the application and not used to limit the scope of the application, and after reading the application, the modifications of various equivalent forms of the application by those skilled in the art all fall within the scope defined by the appended claims of the application.

[0026] As Figure 1 With Figure 2As shown, the present application provides a hypersonic inlet, which comprises an inlet lower wall 1, a lip cover 2 located at the periphery of the inlet lower wall 1, and an inlet inner channel 3 formed between the inlet lower wall and the lip cover. The inlet lower wall 1 is internally provided with a leakage cavity 4, a pressure injection cavity 5 located at the rear of the leakage cavity 4, a pressure injection channel 7 located between the pressure injection cavity 5 and the leakage cavity 4, a piston 8 located in the pressure injection channel 7, a baffle 9, a sliding block 10, a spring 11, a sliding rail 12 for the sliding block 10, and a receiving cavity 13 for surrounding the sliding block. In the embodiment, the leakage cavity 4 is located upstream of the reflection point of the incident shock wave 6 of the lip cover, and it has been verified that this can obtain a better leakage effect (the incident shock wave is indicated by a dashed line in the figure); and the pressure injection cavity 5 is located downstream of the reflection point of the incident shock wave 6 of the lip cover. The leakage cavity 4 and the pressure injection cavity 5 are both in communication with the inlet inner channel 3. Specifically, the inlet lower wall 1 is provided with a plurality of parallel leakage slots 15 and a plurality of parallel pressure injection slots 16. The leakage slots 15 are located above the leakage cavity 4 and are in communication with the leakage cavity 4; and the pressure injection slots 16 are located above the pressure injection cavity 5 and are in communication with the pressure injection cavity 5.

[0027] The receiving cavity 13 is coaxially arranged with the pressure injection channel 7 and is located on both sides of the leakage cavity 4, while the baffle 9 and the receiving cavity 13 are located on the same side of the leakage cavity 4. The receiving cavity 13 is located between the baffle 9 and the leakage cavity 4 and is in communication with the leakage cavity 4. One end of the spring 11 is connected with the baffle 9, and the other end is connected with the sliding block 10. One end of the sliding block 10 is connected with the spring 11, and the other end is connected with the piston 8 through a connecting rod 14.

[0028] When the spring 11 is in a free state, the sliding block is located below the leakage cavity 4 and closes the leakage cavity 4. When the piston 8 moves towards the baffle 9, the piston 8 drives the sliding block 10 to move away from below the leakage cavity 4 to open the leakage cavity 4, and the spring 11 is compressed. When the sliding block 10 moves away from below the leakage cavity 4 to open the leakage cavity 4, the sliding block 10 enters the receiving cavity 13.

[0029] The stiffness coefficient of the spring 11 is less than 1000 N / m, otherwise the leakage flow is too small. On the other hand, when the terminal shock wave is located downstream of the throat, the spring force can push the sliding block 10 to just block the leakage slots 15 to make the inlet no longer leak.

[0030] When the back pressure of the downstream of the inlet increases, the terminal shock wave is transmitted forward under the high back pressure, the high pressure fluid in the terminal shock wave string flows into the injection cavity 5 through the injection gap 16 to drive the piston 8 and the slider 10 to compress the spring 11, the slider 10 is moved away from the lower part of the exhaust cavity 4, the lower wall of the inlet opens the exhaust cavity 4, and the terminal shock wave continues to transmit to the inlet of the exhaust cavity 4. When the high pressure low energy fluid is quickly discharged through the exhaust cavity 4, the anti-back pressure capacity of the inlet is greatly improved, the head of the terminal shock wave can be stabilized at the inlet of the exhaust cavity 4, and the terminal shock wave is no longer transmitted forward. When the back pressure of the downstream of the inlet decreases, the terminal shock wave is withdrawn, and when the head of the terminal shock wave is withdrawn to the downstream of the throat, the slider 10 is withdrawn under the action of the spring 11, the slider 10 blocks the exhaust gap 15, the exhaust cavity 4 is closed, and the inlet is no longer exhausted, which does not affect the flow of the inlet.

[0031] As shown in Figure 3 , the inlet height h of the inlet is determined according to the design requirement, the exhaust gap width 0.125h≤l1≤0.16h. The injection hole width l2<l1, the width of the sliding rail l3>0.4h, the width of the exhaust cavity l4≥3l1, the length of the moving slider l5>1.43h, wherein the thickness of the pressure bearing surface of the moving slider is 0.0625h, and the thickness of the moving slider block is >l4. L is the moving distance of the moving slider, and the size of L reflects the exhaust air volume and the pressure bearing size of the moving slider.

[0032] Next, the effect of the adaptive surge control measure of the hypersonic inlet is verified by combining a specific hypersonic inlet configuration:

[0033] The selected inlet design Mach number is 6, the capture height h0=100mm, h=24mm, h t =17.143mm, ICR=1.4. The inlet adopts two-stage external compression shock wave and one-stage internal compression shock wave, the first-stage compression angle θ1=9°, the second-stage compression angle θ2=10.8°, and the lip compression angle θ3=6°. The total length of the inlet L=586.28mm. The flight height is 25km, at this time the static pressure of the incoming flow p=2549.18, and the static temperature T=221.55k.

[0034] After adding the surge control measure, the exhaust gap width l1=3mm, the injection hole width l2=2mm, and in order to theoretically calculate the pressure bearing size of the moving slider, the inlet is stretched by 50mm along the axial direction. When the head of the terminal shock wave is stabilized at the inlet of the exhaust, the static pressure of the injection port p=219553pa. At this time, the pressure bearing size of the moving slider F=109.77N, and when the moving slider does not block the exhaust cavity, the spring force at this time is approximately equal to 109.77N, and the spring stiffness coefficient is about 732N / m.

[0035] Figure 4The variation curve of the blockage degree of the inlet passage outlet with time is given. The specific implementation steps are: firstly, the inlet passage is tapered, the initial taper position outlet blockage degree TR=25.75%, and the inlet passage outlet blockage degree TR=29.88% is obtained by tapering at a speed of 16 mm / s; then, the tapering is stopped, and the inlet passage is simulated at the fixed taper position. Figure 5 The inlet flow variation curve with time is given. It can be seen that when the adaptive surge control method is not applied to the inlet passage, as the taper moves forward, the inlet passage blockage degree increases, the downstream back pressure of the inlet passage increases rapidly, and the inlet passage enters the unstart surge flow state soon. When the adaptive surge control method is applied to the inlet passage, the inlet flow remains unchanged, and the inlet passage remains in the start state.

[0036] Figure 6 The control configuration bleed flow closing and bleed flow opening Mach cloud diagrams are given, wherein Figure 6 (a) is the Mach cloud diagram in the bleed cavity closing state, Figure 6 (b) is the Mach cloud diagram in the bleed cavity opening state. It can be seen that after the adaptive surge control method is applied to the inlet passage, as the taper moves forward and the blockage degree increases, the downstream back pressure of the inlet passage increases, and under the action of high back pressure, the trailing shock wave is transmitted forward, the high-pressure fluid in the trailing shock wave string flows through the pressure injection cavity to drive the moving slider to move forward, the bleed cavity on the lower wall of the inlet passage is opened, and the trailing shock wave continues to transmit forward to the inlet of the bleed cavity. When the trailing shock wave continues to transmit forward to the inlet of the bleed cavity, the high-pressure low-energy fluid is quickly discharged through the bleed cavity, so that the anti-back pressure capacity of the inlet passage is greatly improved, and the head of the trailing shock wave can be stabilized at the inlet position of the bleed cavity and no longer transmit forward. It can be seen that the adaptive surge control measure greatly improves the anti-back pressure capacity of the inlet passage and widens the surge margin of the inlet passage.

Claims

1. A hypersonic air intake, comprising a lower wall of the air intake and a lip shield located around the lower wall of the air intake; wherein the lower wall of the air intake and the lip shield form an internal channel of the air intake, characterized in that, The lower wall of the air intake duct is provided with a venting chamber, a pressure injection chamber located behind the venting chamber, a pressure injection channel located between the pressure injection chamber and the venting chamber, and a piston located in the pressure injection channel. The lower wall of the air intake duct is also provided with a baffle, a slider, a spring, and a slide rail for the slider to slide. The baffle and the pressure injection channel are located on both sides of the venting chamber. One end of the spring is connected to the baffle and the other end is connected to the slider. One end of the slider is connected to the spring and the other end is connected to the piston through a connecting rod. Both the venting chamber and the pressure injection chamber are connected to the channel inside the air intake duct. When the spring is in a free state, the slider is located below the venting chamber and closes the venting chamber; when the piston moves towards the baffle, the piston drives the slider to move away from below the venting chamber, opening the venting chamber and compressing the spring.

2. The hypersonic air intake according to claim 1, characterized in that, The venting chamber is located upstream of the point where the shock wave is reflected by the air intake lip, while the injection chamber is located downstream of the point where the shock wave is reflected by the air intake lip.

3. The hypersonic air intake according to claim 1 or 2, characterized in that, The spring stiffness coefficient is less than 1000 N / m.

4. The hypersonic air intake according to claim 1 or 2, characterized in that, The lower wall of the air intake is provided with several parallel venting slits, which are located above the venting cavity and communicate with it.

5. The hypersonic air intake according to claim 1 or 2, characterized in that, The lower wall of the air intake is provided with several parallel injection slits, which are located above the injection chamber and communicate with it.

6. The hypersonic air intake according to claim 1 or 2, characterized in that, The lower wall of the air intake is provided with a receiving cavity for surrounding the slider. The receiving cavity is coaxially arranged with the injection channel and located on both sides of the venting cavity. The bottom of the receiving cavity is provided with a slide rail for the slider to slide. When the slider moves away from below the venting cavity to open the venting cavity, the slider enters the receiving cavity.

7. The hypersonic air intake according to claim 1 or 2, characterized in that, The inlet height h of the air intake is determined according to the design requirements. The width of the venting slot is 0.125h≤l1≤0.16h; the width of the injection hole is l2<l1; the width of the slide rail is l3>0.4h; the width of the venting cavity is l4≥3l1; and the length of the moving slider is l5>1.43h.

8. An adaptive surge control method for a hypersonic inlet according to any one of claims 1 to 7, characterized in that, When the downstream back pressure of the intake increases and the final shock wave propagates forward, the high pressure in the final shock wave train drives the moving slider forward, the intake venting chamber opens, and the downstream forward-propagating final shock wave is stabilized; when the downstream back pressure of the intake decreases, the final shock wave retracts, and the moving slider retracts under the action of the spring, without affecting the intake flow rate.

9. The adaptive surge control method according to claim 8, characterized in that, When the shock wave at the end of the downstream intake has not propagated to the throat, the spring force just causes the moving slider to completely block the venting chamber, and at this time there is no mass flow loss in the intake.

10. The adaptive surge control method according to claim 8, characterized in that, When the venting chamber on the lower wall of the intake is open, the final shock wave is stopped at the inlet of the venting chamber when it travels forward, and the intake remains in the starting state.

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