High-efficiency low-resistance wide-speed-domain global flow regulation and control propulsion system and design method thereof

Abstract

The invention relates to a high-efficiency low-resistance wide-speed-domain global flow regulation and control propulsion system and a design method thereof. The propulsion system comprises a speed reduction and pressurization component which is designed by coupling an aircraft forebody and a bulge molded surface; the lip mask can move back and forth along the flow direction; the machine body is provided with an injection channel; an S-bend isolation section; the single-side expansion spray pipe is designed by coupling an inner spray pipe and an aircraft afterbody. The single-degree-of-freedom lip cover capable of moving front and back can achieve real-time matching of bump shock waves and the lip under the working conditions of all working Mach numbers, the overflow resistance of the whole propulsion system is reduced by reducing lip overflow, meanwhile, the area of the secondary flow channel can be adjusted through front-back movement of the lip cover, and therefore flow distribution of the main flow channel and the secondary flow channel is controlled. Not only can choked airflow in a compression section be eliminated, the problem that an air inlet channel is difficult to start under the low Mach number be solved, part of airflow can be secondarily distributed to an injection channel and finally discharged from the exhaust nozzle, and the propelling performance of the exhaust nozzle is effectively improved.

Description

TECHNICAL FIELD

[0001] The application relates to a wide-speed-range variable-geometry propulsion system which can realize global flow regulation while ensuring efficient low-resistance air intake and exhaust and belongs to the technical field of air intake aerodynamic design and flow field control. BACKGROUND

[0002] Compared with the rocket propulsion system used by a spacecraft, an air-breathing engine can obtain oxidizer from the atmospheric environment, thereby reducing the weight of the engine, having a higher specific impulse and being capable of realizing regular horizontal take-off and landing, so that the air-breathing propulsion technology is a key technology for realizing efficient, economic and safe flight in the atmosphere. With people's unremitting pursuit of flying higher, faster and farther, the research and development of a hypersonic (flying Mach number greater than 5) air-breathing propulsion system has become a research hotspot and a key competitive direction of various aerospace powers at present, and the research on air-breathing hypersonic flight technology has a positive and important significance for the development of the military and economic fields.

[0003] With the increase of flight speed, the aerodynamic resistance of the aircraft also increases sharply, and the imbalance of the thrust-to-drag ratio and the decrease of the lift-to-drag ratio are one of the classic difficulties hindering the development of an air-breathing hypersonic aircraft. The aircraft / propulsion system integration technology of coupling the aerodynamic layout and designing the aerodynamic shape of the whole flow field in a wide speed range can take into account the aerodynamic performance of the aircraft and the thrust performance of the air-breathing engine and plays an important role in optimizing the lift-to-drag ratio and the thrust-to-drag ratio. In recent years, various aircraft forebody / air intake integration schemes have appeared and are applied, each having advantages and disadvantages and having certain limitations in use, and it is difficult to meet the demand of flying Mach number across subsonic, transonic, supersonic and even hypersonic and the flight air space from take-off on the ground to 40km or even higher. Therefore, it is necessary to design a propulsion system scheme with a wide flight speed range, simple variable-geometry adjustment and small aerodynamic resistance. SUMMARY

[0004] In order to solve the above technical problems, the application aims to provide a single-degree-of-freedom variable-geometry adjustment mechanism which realizes the dynamic matching of the forebody shock wave and the lip in the working Mach number range, reduces the spillage flow of the lip and reduces the spillage resistance of the whole propulsion system. Meanwhile, the variable-geometry mechanism can also adjust the size of the secondary flow passage, thereby controlling the flow distribution of the primary and secondary flow passages, excluding the compressed air flow, solving the problem of difficult starting of the air intake at low Mach number, allowing part of the air flow to be discharged from the tail nozzle through the injection channel and effectively improving the propulsion performance of the nozzle.

[0005] In addition, the propulsion system of the method is designed by coupling the air inlet with the front body of the aircraft and coupling the tail nozzle with the rear body of the aircraft. The integrated coupling design of the air inlet and the body can utilize the pre-compression of the far front airflow by the front body of the aircraft to increase the compression efficiency of the air inlet and reduce the total pressure loss. The coupling design of the tail nozzle and the rear body makes the inner nozzle a single-side expansion nozzle, increases the expansion area of the nozzle, and thus improves the expansion ratio and the propulsion efficiency. In general, the integrated coupling design of the inner and outer flows can optimize the performance of the propulsion system as a whole and has obvious effects on the improvement of the thrust-drag ratio and the lift-drag ratio.

[0006] To achieve the above-mentioned purpose, the application first designs a high-efficiency low-drag wide-speed-range global flow regulation propulsion system, which comprises a deceleration and pressure-increasing component designed by coupling a front body of an aircraft and a bulge surface; a lip cover movable forward and backward along the flow direction; a body with an injection channel; an S-shaped isolation section; a ramjet channel; and a single-side expansion nozzle designed by coupling an inner nozzle and a rear body of the aircraft.

[0007] Further, the rear of the front body of the aircraft is coupled with the bulge surface.

[0008] Further, the lip cover is adjustable and movable forward and backward along the flow direction, and a secondary flow channel is arranged between the bulge surface and the adjustable lip cover.

[0009] Further, the structure of coupling the tail nozzle with the rear body of the aircraft makes the inner nozzle a single-side expansion nozzle.

[0010] On the other hand, the application also provides a design method of a high-efficiency low-drag wide-speed-range global flow regulation propulsion system, which is applied to the case where the Mach number is Ma2-Ma10.

[0011] In the low Mach number working condition, the bulge shock wave is in the front edge of the lip, the lip has less overflow, and the overflow resistance is small; the far front airflow is pre-compressed by the body, and then enters the inner flow passage after being decelerated and pressurized by the compression section;

[0012] Before the inlet section of the isolation section, the airflow required by the downstream engine flows into the S-shaped isolation section, and after passing through the ramjet, becomes the main flow injected by the inner nozzle; the excess airflow is distributed into the secondary flow channel for secondary distribution, part of the airflow is directly discharged into the atmosphere, and the other part enters the injection channel to mix with the airflow in the main flow area of the nozzle, and finally flows out from the single-side expansion nozzle;

[0013] With the increase of the Mach number of the incoming flow, the adjustable lip is moved horizontally along the flow direction, and under the condition of keeping the real-time matching of the bulge shock wave and the lip, the flow distribution of the captured air flow is changed by reducing the area of the secondary flow passage;

[0014] According to the relationship between the area of the secondary flow passage and the moving distance of the adjustable lip, the variation law of the non-dimensional parameter of the opening and closing area of the secondary flow passage with the Mach number of the incoming flow is obtained; when the Mach number of the incoming flow reaches Ma10, the adjustable lip reaches the limit position, at this time, the secondary flow passage is completely closed, the injection passage becomes a dead cavity, and the geometry of the inner nozzle is finally formed into an aerodynamic profile; after the hypersonic air flow passing through the bulge shock wave is decelerated and pressurized, the air flow is further decelerated and pressurized by the lip reflection shock wave and various background wave systems, and then is discharged into the atmosphere by the single-side expansion nozzle after passing through the S-bend isolation section and the ramjet engine.

[0015] Beneficial effects:

[0016] On the basis of the above-mentioned global flow regulation air intake and exhaust scheme, the coupling design of the bulge profile and the aircraft forebody can form an integrated air intake scheme with high efficiency and low resistance, and the coupling design of the nozzle profile and the aircraft afterbody can change the inner nozzle into a single-side expansion nozzle, thereby effectively improving the propulsion performance of the entire aircraft. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a symmetric surface schematic view of the air intake and exhaust system and the coupling integrated design scheme of the aircraft forebody and afterbody under a low Mach number working condition, which is shown in the embodiment of the present application;

[0018] Figure 2 is a symmetric surface schematic view of the air intake and exhaust system and the coupling integrated design scheme of the aircraft forebody and afterbody under a high Mach number working condition, which is shown in the embodiment of the present application;

[0019] Figure 3 is a linear law graph of the non-dimensional parameter of the secondary flow passage area, which changes with the Mach number of the incoming flow;

[0020] Figure 4 is a symmetric surface schematic view of the air intake and exhaust system under a low Mach number working condition, which is shown in the embodiment of the present application;

[0021] Figure 5 is a symmetric surface schematic view of the air intake and exhaust system under a high Mach number working condition, which is shown in the embodiment of the present application;

[0022] In the drawings: 1-aircraft forebody, 2-bulge profile, 3-adjustable lip, 4-secondary flow passage, 5-injection passage, 6-single-side expansion nozzle, 7-aircraft afterbody, 8-inner nozzle, 9-ramjet engine part, 10-S-bend isolation section;

[0023] A leak represents the area of the secondary flow passage, Ae wherein A0 represents an exit cross-sectional area, and Ma0 represents an incoming flow Mach number. DETAILED DESCRIPTION

[0024] For the convenience of understanding the present application, the method of the present application will be further described in combination with a specific propulsion system scheme. The following examples are only used to more clearly illustrate the technical method of the present application, and cannot be interpreted as a limitation of the present application.

[0025] Example 1:

[0026] The present application first designs a high-efficiency low-resistance wide-speed-range global flow regulation propulsion system, which comprises a deceleration and pressurization component designed by coupling a forebody of an aircraft and a bulge surface; a lip cover movable forward and backward along a flow direction; a body with an injection channel; an S-bend isolation section; a ramjet engine channel; and a single-side expansion nozzle designed by coupling an inner nozzle and an aft body of the aircraft.

[0027] The specific working principle is that the single-degree-of-freedom adjustable lip cover can be adjusted forward and backward along the flow direction according to the inclination angle of the bulge shock wave under different incoming flow Mach numbers and the inlet target flow capture requirement. During the forward and backward movement of the lip cover, the opening and closing area of the secondary flow channel will also change. In the starting state of the inlet, it is considered that the front cross section of the isolation section inlet is supersonic airflow, so the opening and closing area of the secondary flow system can reflect the size of the bypass channel displacement flow.

[0028] Further, the rear of the aircraft forebody is a bulge surface, and the rear of the aircraft forebody is coupled with the bulge surface.

[0029] Further, the adjustable lip cover is on the bulge surface; the adjustable lip cover is a deceleration and pressurization component, which can move forward and backward along the flow direction, and the secondary flow channel is between the bulge surface and the adjustable lip cover.

[0030] Further, the structure of coupling the tail nozzle with the aircraft aft body makes the inner nozzle become a single-side expansion nozzle

[0031] Based on the propulsion system provided in Example 1, the present application further provides a design method of a high-efficiency low-resistance wide-speed-range global flow regulation propulsion system, specifically:

[0032] When the incoming flow Mach number is the highest in the design speed range, the adjustable lip is located at the most rear position, at which time the upper wall of the minimum cross section in the compression section and the upper wall of the inlet cross section of the isolation section are completely fitted, the secondary flow channel is completely closed, the air flow enters the inner channel after deceleration and pressure increase through the bulge surface, passes through the S-shaped inlet channel, flows into the ramjet engine, and finally is discharged from the inner nozzle. With the decrease of the incoming flow Mach number, the adjustable lip moves forward along the flow direction, keeps the bulge shock wave and the lip port as a time seal state, reduces the lip overflow, and thus reduces the overflow resistance. With the forward movement of the lip, the distance between the upper wall of the inlet cross section of the isolation section and the upper wall of the movable lip gradually increases, that is, the inlet area of the secondary flow system gradually increases. The existence of the secondary flow system can discharge the excess air flow in the main flow area, so as to solve the problem of throat choking at low incoming flow Mach number, and ensure the starting performance of the inlet channel. Moreover, the secondary flow system is further divided into two channels downstream, part of the air flow directly flows into the atmosphere through one of the channels, and part of the air flow enters the inner nozzle through the injection channel, and then is mixed with the air flow in the main flow area to improve the overall kinetic energy of the fluid and thus improve the propulsion performance of the nozzle. When the incoming flow Mach number decreases to the lowest point in the design speed range, the movable lip is located at the front limit position, at which time the contraction ratio of the inlet channel is the smallest, and the opening area of the secondary flow system is the largest, the air flow required by the downstream engine flows into the inner channel through the inlet cross section of the isolation section, and part of the excess choked air flow flows out of the inner nozzle through the injection channel, and another part flows out of the inlet and exhaust system through the bypass.

[0033] The working range of the integrated propulsion system in the embodiment of the application is Ma2-Ma10, the design Mach number is Ma6, and the minimum starting Mach number is Ma2. The integrated propulsion system mainly comprises: a deceleration and pressure increase component coupled with a flight vehicle forebody 1 and a bulge surface 2, a movable adjustable lip 3 which can move forward and backward along the flow direction; a body with an injection channel 5; an S-shaped isolation section 10; a ramjet engine part 9 channel; and a single-side expansion nozzle 6 coupled with an inner nozzle 8 and a flight vehicle afterbody 7, as shown in Figure 1 and Figure 2 .

[0034] Figure 1 When the incoming flow Mach number is Ma3, the integrated coupled design propulsion system is shown in the schematic view of the symmetry plane. Under this Mach number working condition, the bulge shock wave just hits the front edge of the lip, and because the lip overflow is small, the overflow resistance is also small. The far front incoming flow passes through the pre-compression of the body, and then enters the inner channel after deceleration and pressure increase of the compression section. Before the inlet cross section of the isolation section, the air flow required by the downstream engine will flow into the S-shaped isolation section, and after passing through the ramjet engine, becomes the main flow which is discharged from the inner nozzle. The excess air flow which is choked will flow into the secondary flow channel and be distributed again, part of the air flow is directly discharged into the atmosphere, and another part enters the injection channel, then is mixed with the air flow in the main flow area of the nozzle, and finally flows out of the single-side expansion nozzle.

[0035] As the incoming Mach number increases, the adjustable lip shield moves horizontally backward along the flow direction. While maintaining the real-time matching between the bulge shock wave and the lip, the flow distribution of the captured airflow is changed by reducing the secondary flow channel area. In the embodiment of the present invention, the secondary flow channel area is related to the movement distance of the adjustable lip shield. Therefore, the dimensionless parameter of the secondary flow channel opening and closing area can be obtained. The law of change with the incoming Mach number is as follows: Figure 3 When the incoming Mach number reaches Ma10, as shown in Figure 2 As shown, the adjustable lip reaches its rearward limit, completely closing the secondary flow channel and transforming the ejector channel into a dead space. The missing geometric profile of the inner nozzle eventually forms an aerodynamic profile due to pressure balance on both sides of the cross section. Thus, after entering the inner flow channel, the hypersonic airflow, decelerated and pressurized by the bulge shock wave, is further decelerated and pressurized by the lip's reflected shock wave and various background waves. After passing through the S-bend isolation section and the ramjet, it is discharged into the atmosphere through the unilateral expansion nozzle.

[0036] By decoupling the above-mentioned propulsion system and removing the aircraft body, the intake and exhaust system of the embodiment of the present invention can be obtained. Figure 4 and Figure 5 The coupling design of the intake and exhaust system with the aircraft body is only intended to further improve the lift-to-drag and thrust-to-drag ratios. The principle of global flow control through the adjustable lip is the same as that of the integrated propulsion system, so it will not be elaborated on in detail.

[0037] Obviously, the integrated propulsion system design scheme operating at Mach 2 to Mach 10 demonstrated in the embodiment of the present invention is only a special case of the present invention's method. Its purpose is to demonstrate the matching of the adjustable lip position with the bulge shock wave moment under different Mach number conditions, as well as the secondary distribution and control process of the captured flow by the adjustable lip, thereby proving the feasibility of the propulsion system design scheme. Therefore, all technical ideas proposed in this invention, or any modifications made based on this technical scheme, fall within the scope of protection of this invention.

Claims

1. A high-efficiency, low-resistance, wide-speed range, global flow control propulsion system, characterized by: The propulsion system comprises a deceleration and pressurization component designed by coupling the front body of the aircraft and the bulge profile; a lip cover that can move forward and backward along the airflow; and a body with an ejection channel. S The curved isolation section; the ramjet engine channel and the unilateral expansion nozzle designed by coupling the inner nozzle and the rear body of the aircraft.

2. The high-efficiency, low-resistance, wide-speed range, global flow control propulsion system according to claim 1 is characterized in that: The rear of the aircraft front body is a bulge-shaped surface, and the rear of the aircraft front body is a bulge-shaped surface coupled.

3. The high-efficiency, low-resistance, wide-speed range, global flow control propulsion system according to claim 1 is characterized in that: An adjustable lip cover is provided on the bulging surface; the adjustable lip cover is a deceleration and pressurization component, which can move forward and backward along the flow, and a secondary flow channel is provided between the bulging surface and the adjustable lip cover.

4. The high-efficiency, low-resistance, wide-speed range, global flow control propulsion system according to claim 1 is characterized in that: The tail nozzle is coupled to the rear body of the aircraft, so that the inner nozzle becomes a unilateral expansion nozzle.

5. A design method for a high-efficiency, low-resistance, wide-speed range, global flow control propulsion system, characterized by: The design method is directed to the high-efficiency, low-resistance, wide-speed range global flow control propulsion system according to any one of claims 1 to 4, and the propulsion system is applied to a Mach coefficient Ma 2~ Ma 10 cases; Under low Mach number conditions, the bulge shock wave is at the leading edge of the lip, resulting in less lip overflow and less overflow resistance. The incoming flow from far ahead is pre-compressed by the fuselage, and then decelerated and pressurized in the compression section before entering the inner flow channel. Before the inlet section of the isolation section, the airflow required by the downstream engine is met S The air flows into the bend isolation section and becomes the mainstream of the inner nozzle after passing through the ramjet engine. The excess airflow is blocked and flows into the secondary flow channel for secondary distribution. Part of the airflow is directly discharged into the atmosphere, and the other part enters the ejection channel and kinetically mixes with the airflow in the mainstream area of ​​the nozzle. Finally, they flow out of the single-sided expansion nozzle together. As the incoming flow Mach number increases, the adjustable lip moves horizontally backward along the flow direction. While maintaining the real-time matching between the bulge shock wave and the lip, the flow distribution of the captured airflow is changed by reducing the area of ​​the secondary flow channel. According to the relationship between the secondary flow channel area and the moving distance of the adjustable lip mask, the dimensionless parameter of the secondary flow channel opening and closing area is obtained as the change law of the incoming flow Mach number; when the incoming flow Mach number reaches Ma At 10 o'clock, the adjustable lip mask reaches the rear limit position. At this time, the secondary flow channel is completely closed, the ejection channel becomes a dead cavity, and the missing geometric surface of the inner nozzle finally forms an aerodynamic surface. After the hypersonic airflow decelerated and pressurized by the bulge shock wave enters the inner flow channel, it is further decelerated and pressurized by the shock wave reflected by the lip and various background waves. S After the curved isolation section and ramjet engine, it is discharged into the atmosphere through a single-sided expansion nozzle.

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