Blunt forebody hypersonic vehicle drag reduction and heat reduction structure

Abstract

The application discloses a blunt forebody hypersonic vehicle high-speed flight drag reduction and heat reduction structure and belongs to the field of hypersonic vehicle aerodynamic drag reduction and heat reduction. The application comprises an aerodynamic disc expansion half-angle section, an aerodynamic disc, a shock wave needle, a flow channel, a blunt forebody and a jet working medium inlet. The flow channel comprises a reverse flow guide channel, a throttle control section, a blunt forebody wall surface flow guide channel and a blunt forebody wall surface jet outlet section. The blunt forebody comprises an upstream part and a downstream part. The blunt forebody wall surface flow guide channel is a spherical head type air slot covering the upstream part. The blunt forebody wall surface jet outlet section is an annular nozzle. The jet cooling working medium is sprayed from the jet working medium inlet and flows from right to left. When flowing through the throttle control section, the jet cooling working medium is divided into two parts, one part flows to the reverse flow guide channel and the other part flows to the blunt forebody wall surface flow guide channel. The application combines the shock wave needle and the jet, adopts the aerodynamic disc, the shock wave needle, the flow channel and the jet to protect the blunt forebody and improves the efficiency of drag reduction and heat reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to a drag-reducing and heat-reducing structure of a hypersonic vehicle, in particular to a drag-reducing and heat-reducing structure for a blunt forebody of a hypersonic vehicle, and belongs to the field of aerodynamic drag reduction and heat reduction of hypersonic vehicles. BACKGROUND

[0002] With the progress of modern aerospace science and technology, the demand for hypersonic vehicles is increasing. Hypersonic vehicles have great speed advantage and are regarded as a new milestone and commanding point in the field of aerospace. In addition, their strong fast reaction and high penetration ability are valued by civil and military fields of various countries, and have become one of the hot research issues in the world today. However, hypersonic vehicles face two major challenges during flight: drag reduction and heat reduction. First, during flight, the flow and the surface of the vehicle are in severe friction, resulting in a harsh aerodynamic heat environment. In order to reduce the stagnation temperature of the hypersonic vehicle and avoid the ablation of the aerodynamic shape and the destruction of the internal control system of the vehicle, the head of the vehicle generally does not adopt a sharp cone configuration with small curvature, but a blunt forebody configuration with an anti-ablation layer. The blunt forebody of the hypersonic vehicle will generate a bow shock during flight, thereby dissipating a large amount of heat energy generated by the hypersonic vehicle through the shock wave surface. However, when the vehicle is in hypersonic flight, the compression of the flow through the bow shock will still cause the temperature of the free flow to rise sharply, which may cause serious thermal damage to the structure and electronic equipment of the vehicle; at the same time, the strong bow shock is the main component of the total drag of the vehicle, which reduces the lift-drag ratio of the vehicle, destroys the aerodynamic performance, and intensifies the fuel consumption, also reducing the carrying capacity of the vehicle; in order to cope with the two major flight challenges of drag reduction and heat reduction, the vehicle needs to be equipped with a drag-reducing and heat-reducing system to meet the extreme aerodynamic force and heat environment under various working conditions in the flight envelope. Therefore, drag reduction and heat reduction have become an important topic in the research of hypersonic vehicles. In the past, the thermal protection performance has been improved through the development of new materials. However, the traditional passive thermal protection method cannot meet the requirements of the severe aerodynamic heating environment for a long time. In addition, relying only on new heat-resistant materials cannot meet the requirements of drag reduction and flight distance. Based on the background technology and development needs of hypersonic vehicles, in view of the high drag and heat problems faced by hypersonic vehicles, a shock wave pin-duct-jet combined configuration is proposed. The shock wave pin-duct-jet combined configuration considers how to add the jet to the flow field. Based on the flow-heat coupling method, the jet and the slot configuration are adopted, so that the jet is added to the outer flow field after flowing through the slot, and the heat exchange between the blunt forebody wall and the flow in the slot is expanded, the strength of the reattachment shock wave and the shock wave-shock wave interaction is weakened, the reattachment point of the shear layer on the blunt forebody wall of the single shock wave pin configuration is removed, and the drag-reducing and heat-reducing target of the blunt forebody wall is achieved. SUMMARY

[0003] In view of the serious aerodynamic heat problem faced by the blunt forebody aircraft when flying at hypersonic speed in the near space, the main purpose of the present application is to provide a blunt forebody aircraft hypersonic flight drag reduction and heat reduction structure, which combines shock wave needles and jets, adopts aerodynamic discs, shock wave needles, flow guide channels and jets to protect the blunt forebody, and improves the efficiency of aircraft drag reduction and heat reduction.

[0004] The purpose of the present application is realized by the following technical solutions.

[0005] The application discloses a blunt forebody hypersonic flight drag reduction and heat reduction structure, which comprises an aerodynamic disc expansion half-angle section, an aerodynamic disc, a shock wave needle, a flow channel, a blunt forebody and a jet working medium inlet; the flow channel comprises a reverse flow guide channel, a throttling control section, a blunt forebody wall flow guide channel and a blunt forebody wall jet outlet section; the blunt forebody comprises an upstream part of the blunt forebody and a downstream part of the blunt forebody. The aerodynamic disc and the shock wave needle are obtained by integrated machining, wherein the shock wave needle is an elongated cylindrical rod with an equal cross section, the aerodynamic disc and the shock wave needle are machined by means of casting, 3D printing, extrusion forming, drawing machining, roll forming or laser cutting, and are subjected to grinding and polishing, spraying, chemical treatment and other machining operations, so as to improve the dimensional accuracy and the oxidation resistance and obtain good surface quality. The high-depth-hole and the deep hole formed by the aerodynamic disc expansion half-angle section, the reverse flow guide channel and the throttling control section are obtained by means of electric spark machining, laser machining, chemical mechanical grinding or electrochemical machining. After the deep hole formed by the aerodynamic disc expansion half-angle section, the reverse flow guide channel and the throttling control section is machined, quality control and performance verification are carried out: firstly, the hole wall smoothness and flatness are ensured, and polishing and chemical treatment are adopted to improve the surface quality; secondly, the size parameters (hole diameter, hole depth, hole position, hole inclination and hole surface roughness) of the deep hole are accurately measured to ensure that the requirements are met; and then burrs are removed, the hole is thoroughly cleaned by means of cleaning and the hole wall is subjected to surface treatment to improve the wear resistance and corrosion resistance. The shock wave needle and the upstream part of the blunt forebody are connected by mechanical connection, welding or bonding, and the elongated cylindrical rod-shaped shock wave needle with an equal cross section is installed at the stagnation point of the leading edge of the upstream part of the blunt forebody. The mechanical connection uses bolts, rivets and the like to firmly fix the shock wave needle and the upstream part of the blunt forebody together. This connection mode has high reliability and is easy to disassemble and maintain; the welding connection can form a more integrated structure and has high weld strength and good fatigue resistance; and the bonding connection bonds the shock wave needle and the upstream part of the blunt forebody together by using high-performance structural adhesive, and the connection strength is high and the stress distribution is uniform. The upstream part of the blunt forebody and the downstream part of the blunt forebody are obtained by casting, forging, die casting and 3D printing, and then are connected by a connection mode similar to that of the shock wave needle and the upstream part of the blunt forebody, so as to obtain the blunt forebody wall flow guide channel, the blunt forebody wall jet outlet section and the jet working medium inlet. The blunt forebody wall flow guide channel is a ball head type air slot covering the upstream part of the blunt forebody; and the blunt forebody wall jet outlet section is an annular nozzle. After the aerodynamic disc expansion half-angle section, the aerodynamic disc, the shock wave needle, the flow channel, the blunt forebody and the jet working medium inlet are machined and connected, the jet cooling working medium is sprayed out from the jet working medium inlet, and the cooling working medium flows from right to left. When flowing through the throttling control section, the jet cooling working medium is divided into two parts, one part flows to the reverse flow guide channel and the other part flows to the blunt forebody wall flow guide channel.Specifically, for the reverse jet flow, due to the sudden change of the cross section of the throttle control section, the reverse jet flow part is decelerated to subsonic speed, the pressure is continuously increased, and the reverse jet flow is continuously accelerated in the reverse flow channel, and is accelerated to supersonic speed at the end of the reverse flow channel. In order to further increase the injection speed of the reverse jet flow, the designed aerodynamic disc expansion half-angle section has the effect of expanding the flow channel, can accelerate supersonic flow, and forms typical structures such as Mach disc one and barrel shock wave one; for the blunt forebody shoulder jet flow, due to the sudden change of the cross section of the throttle control section, part of the cooling working medium is diverted to the blunt forebody wall flow channel, and a series of compression waves are formed due to the throttling effect of the throttle control section. After the jet cooling medium passes through the compression wave, it is decelerated to subsonic speed, continues to flow in the blunt forebody wall flow channel, and a series of expansion waves are formed due to the expansion effect of the flow channel caused by the change of the geometric shape. After the jet passes through the expansion wave, the pressure is reduced, and near the blunt forebody wall jet outlet section, due to the blocking effect, an adverse pressure gradient is formed in the blunt forebody wall flow channel, flow separation occurs near the left channel, a very thin shear layer and a vortex structure are formed, and due to the large difference between the internal and external pressures, a highly under-expanded shoulder jet flow is formed at the blunt forebody wall jet outlet section, including barrel shock wave two, Mach disc two and other typical structures. The reverse jet flow and the shoulder jet flow have the effects of flow field reconstruction and adding cooling working medium, and the reverse jet flow pushes away the arc-shaped shock wave in front of the aerodynamic disc far away from the aerodynamic disc; the shoulder jet flow makes the shear layer on the shock wave pin move away from the wall, moves the position where the shear layer reattaches to the blunt forebody wall downstream, expands the recirculation zone in front of the blunt forebody, weakens the shock wave-shock wave interaction in front of the blunt forebody, reduces the intensity of the reattached shock wave and moves it away from the blunt forebody; at the same time, the low-temperature gas in the reverse flow channel and the blunt forebody wall flow channel can also cool the incoming flow through the solid wall of the shock wave pin and the upstream part of the blunt forebody, and reduce the thermal load of the structure; the above-mentioned are all conducive to improving the drag reduction and heat reduction effect of the hypersonic blunt forebody vehicle.

[0006] The working method of the hypersonic flight drag reduction and heat reduction structure of the blunt forebody aircraft disclosed in the application is as follows: the incoming flow is compressed intensively at the head of the shock wave needle to form a detached bow shock wave, and then the bow shock wave is converted into a leading edge oblique shock wave, and the reverse jet (Mach disc 1 and barrel shock wave 1) pushes the bow shock wave away from the head of the shock wave needle; the incoming flow separates at the shoulder of the aerodynamic disc, and then reattaches the shock wave needle, and a vortex structure and an upstream reattachment shock wave are generated behind the aerodynamic disc; the incoming flow flows downstream along the shock wave needle, and due to the influence of the adverse pressure gradient, flow separation occurs on the shock wave needle to form a shear layer and a separation shock wave. Downstream of the flow separation point of the shock wave needle, the shock wave needle, the shear layer and the upstream part of the blunt forebody form a conical recirculation zone. Due to the introduction of the shoulder jet, the reattachment of the shear layer to the blunt forebody generates a reattachment shock wave, which is converted into a reattachment shock wave generated by the interaction of the shoulder jet and the incoming flow. In the shock wave needle-guide channel-jet combination configuration, the flow direction of the incoming flow changes after passing through the reattachment shock wave, and is parallel to Mach disc 2 of the shoulder jet. The shock wave needle-guide channel-jet combination configuration causes the flow separation to occur in advance at the shock wave needle, and the recirculation zone formed is significantly larger than that of the pure shock wave needle configuration, so that the upstream part of the blunt forebody and the downstream part of the blunt forebody in the shock wave needle-guide channel-jet combination configuration are wrapped in the recirculation zone to a greater extent, and the high-temperature gas compressed by the bow shock wave and the leading edge shock wave is isolated outside and cannot directly heat the upstream part of the blunt forebody and the downstream part of the blunt forebody. Due to the shoulder jet located in the reattachment region of the shear layer, the shear layer cannot reattach to the original position in the shock wave needle-guide channel-jet combination configuration. For the shoulder jet, due to the effect of the incoming flow, the back pressure on the two sides of the shoulder jet is different, causing the shoulder jet to tilt downstream; due to the Mach disc 2, barrel shock wave 2 and the stagnation effect of the incoming flow, small vortex structures are formed on the two sides of the shoulder jet. The blunt forebody aircraft hypersonic flight drag reduction and heat reduction structure realizes the drag reduction and heat reduction effect on the upstream part of the blunt forebody and the downstream part of the blunt forebody by controlling the wave structure, injecting cooling working medium and fluid-structure coupling heat exchange medium.

[0007] In order to improve the drag reduction and heat reduction effect, as preferred, the diameter D of the aerodynamic disc is 0.2-0.5 times the diameter D of the blunt forebody. d The diameter D of the aerodynamic disc is 0.2-0.5 times the diameter D of the blunt forebody.

[0008] In order to improve the drag reduction and heat reduction effect, as further preferred, the diameter D of the aerodynamic disc is 0.3 times the diameter D of the blunt forebody. d The diameter D of the aerodynamic disc is 0.3 times the diameter D of the blunt forebody.

[0009] In order to improve the drag reduction and heat reduction effect, as preferred, the length L of the shock wave needle is 0.5-2 times the diameter D of the blunt forebody.

[0010] In order to improve the drag reduction and heat reduction effect, as further preferred, the length L of the shock wave needle is 2 times the diameter D of the blunt forebody.

[0011] The aerodynamic disc is provided with an aerodynamic disc expansion half-angle section and a reverse flow guide channel for discharging reverse jet flow, preferably, the reverse flow guide channel is designed as a Laval nozzle to reduce total pressure loss, and the angle θ of the aerodynamic disc expansion half-angle section is set to 0-70°, so as to enhance the push-off effect of the reverse jet flow on the bow shock, and further improve the drag reduction and heat reduction effect.

[0012] As a further preferred, the angle θ of the aerodynamic disc expansion half-angle section is set to 70°, so as to produce a flow channel expansion effect, obviously accelerate the supersonic reverse jet flow at the end of the reverse flow guide channel, make the reverse jet flow structure more obvious as far as possible, and further improve the drag reduction and heat reduction effect.

[0013] As a preferred, the aerodynamic disc is chamfered at the sharp corner part to weaken the thermal stress concentration and ablation phenomenon of the aerodynamic disc.

[0014] The blunt forebody is provided with a throttle control section, a blunt forebody wall surface flow guide channel and a blunt forebody wall surface jet flow outlet section for discharging shoulder jet flow, preferably, the wall surface thickness T of the upstream part of the blunt forebody is set to 0.1-0.2 times of the diameter D of the blunt forebody, the opening of the blunt forebody wall surface flow guide channel is designed as a Laval nozzle to reduce total pressure loss, obviously accelerate the shoulder jet flow, make the shoulder jet flow structure more obvious as far as possible, and further improve the drag reduction and heat reduction effect.

[0015] As a further preferred, the wall surface thickness T of the upstream part of the blunt forebody is set to 0.1 times of the diameter D of the blunt forebody, so as to enhance the heat exchange performance between the cooling working medium in the blunt forebody wall surface flow guide channel and the flow under the condition of meeting the structural strength, and further improve the drag reduction and heat reduction performance.

[0016] As a preferred, the diameter D of the throttle control section is set to 0.5-0.8 times of the diameter D of the jet flow working medium inlet. o As a preferred, the diameter D of the throttle control section is set to 0.5-0.8 times of the diameter D of the jet flow working medium inlet. j By proportionally controlling the cooling working medium flow to the reverse jet flow and the shoulder jet flow, the drag reduction and heat reduction effect is further improved.

[0017] As a further preferred, the diameter D of the throttle control section is set to 0.6 times of the diameter D of the jet flow working medium inlet. o As a further preferred, the diameter D of the throttle control section is set to 0.6 times of the diameter D of the jet flow working medium inlet. j As a further preferred, the diameter D of the throttle control section is set to 0.6 times of the diameter D of the jet flow working medium inlet. Advantages

[0018] 1. The blunt forebody aircraft hypersonic flight drag reduction and heat reduction structure disclosed in the application, a flow channel comprises a reverse flow guide channel, a throttle control section, a blunt forebody wall surface flow guide channel, a blunt forebody wall surface jet flow outlet section; the blunt forebody comprises a blunt forebody upstream part and a blunt forebody downstream part. The aerodynamic disc expansion half-angle section, the aerodynamic disc, the shock wave needle, the flow channel and the jet flow working medium inlet are used to protect the blunt forebody, so as to achieve the drag reduction and heat reduction target.

[0019] 2. The blunt forebody hypersonic vehicle flying drag reduction and heat reduction structure disclosed in the application, when flying at hypersonic speed, the flow is compressed by the shock needle head to form a detached bow shock, and then the bow shock is transformed into a leading edge oblique shock, the reverse jet flow pushes the bow shock away from the shock needle head; the flow separates at the aerodynamic disc shoulder, and then reattaches to the shock needle, and a vortex structure and an upstream reattachment shock are generated behind the aerodynamic disc; the flow flows downstream along the shock needle, and due to the influence of the adverse pressure gradient, flow separation occurs on the shock needle, forming a shear layer and a separation shock. Downstream of the flow separation point of the shock needle, the shock needle, the shear layer and the upstream part of the blunt forebody form a conical recirculation zone. Due to the introduction of the shoulder jet flow, the shear layer reattaches to the blunt forebody to generate a reattachment shock, which is transformed into a reattachment shock generated by the interaction of the shoulder jet flow and the flow. In the shock needle-guide channel-jet flow combination configuration, the flow direction changes after passing through the reattachment shock, and is parallel to the shoulder jet flow Mach disc. The shock needle-guide channel-jet flow combination configuration separates earlier than the pure shock needle configuration, and the recirculation zone formed is significantly larger than that of the pure shock needle configuration, which makes the upstream part of the blunt forebody and the downstream part of the blunt forebody of the shock needle-guide channel-jet flow combination configuration be wrapped in the recirculation zone in a larger range, and the high-temperature gas compressed by the bow shock and the leading edge shock is isolated outside, and cannot directly heat the upstream part of the blunt forebody and the downstream part of the blunt forebody, thereby achieving the purpose of drag reduction and heat reduction.

[0020] 3. The blunt forebody hypersonic vehicle flying drag reduction and heat reduction structure disclosed in the application, the cooling medium discharged from the jet flow medium inlet is suddenly changed in cross section through the throttling control section, part of the cooling medium is divided into the blunt forebody wall guide channel, due to the throttling effect of the throttling control section, a series of compression waves are formed, the jet cooling medium is decelerated to subsonic speed after passing through the compression waves, and continues to flow in the blunt forebody wall guide channel, due to the expansion effect of the flow channel caused by the change of the geometric shape, a series of expansion waves are formed, the pressure of the jet flow is reduced after passing through the expansion waves, and due to the blocking effect near the blunt forebody wall jet outlet section, an adverse pressure gradient is formed in the blunt forebody wall guide channel, flow separation occurs near the left side channel, forming a very thin shear layer and a vortex structure, and a highly under-expanded shoulder jet flow is formed at the blunt forebody wall jet outlet section due to the large difference between the internal and external pressures. The reverse jet flow and the shoulder jet flow have the effects of flow field reconstruction and cooling medium addition, the reverse jet flow pushes the bow shock in front of the aerodynamic disc away from the aerodynamic disc; the shoulder jet flow makes the shear layer on the shock needle move away from the wall, moves the position where the shear layer reattaches to the blunt forebody wall downstream, expands the recirculation zone in front of the blunt forebody, weakens the shock-shock interaction in front of the blunt forebody, reduces the intensity of the reattachment shock and makes it move away from the blunt forebody; at the same time, the low-temperature gas in the reverse guide channel and the blunt forebody wall guide channel can also cool the flow through the solid wall of the shock needle and the upstream part of the blunt forebody, reducing the thermal load of the structure.

[0021] 4. The blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application injects cooling medium through the jet working medium inlet in the reverse flow channel and the blunt forebody wall surface flow channel, and then realizes drag reduction and heat reduction through heat exchange, wave system structure control and direct cooling, etc., so as to keep the aerodynamic configuration of the hypersonic vehicle unchanged as much as possible and avoid flight performance reduction, and the combination configuration of the shock wave needle and the jet realizes the load reduction effect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The two-dimensional engineering drawing of the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application is shown.

[0023] Figure 2 The structure size drawing of the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application is shown.

[0024] Figure 3 The three-dimensional schematic view of the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application is shown.

[0025] Figure 4 The two-dimensional axisymmetric flow field view of the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application is shown.

[0026] Figure 5 The temperature cloud view of the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application is shown.

[0027] Wherein: 1 - aerodynamic disc expansion half angle section, 2 - aerodynamic disc, 3 - shock wave needle, 4 - flow channel, 5 - blunt forebody, 6 - jet working medium inlet; 4 - flow channel includes: 4.1 - reverse flow channel, 4.2 - throttling control section, 4.3 - blunt forebody wall surface flow channel, 4.4 - blunt forebody wall surface jet outlet section; 5 - blunt forebody includes: 5.1 - blunt forebody upstream portion, 5.2 - blunt forebody downstream portion. DETAILED DESCRIPTION

[0028] As shown in Figure 1 , 2 , 3, the blunt forebody hypersonic vehicle flight drag reduction and heat reduction structure disclosed in the present application includes the aerodynamic disc expansion half angle section 1, the aerodynamic disc 2, the shock wave needle 3, the flow channel 4, the blunt forebody 5 and the jet working medium inlet 6; the flow channel 4 includes the reverse flow channel 4.1, the throttling control section 4.2, the blunt forebody wall surface flow channel 4.3 and the blunt forebody wall surface jet outlet section 4.4; the blunt forebody 5 includes the blunt forebody upstream portion 5.1 and the blunt forebody downstream portion 5.2, and the diameter D of the blunt forebody 5 is 50 mm. The aerodynamic disc 2 and the shock wave needle 3 are obtained through integral machining, wherein the aerodynamic disc 2 is a cylindrical disc, the thickness D t0.05 times the diameter D of the blunt precursor 5, the diameter D d 0.3 times the diameter D of the blunt precursor 5, the shock needle 3 is an elongated cylindrical rod with a constant cross section, the diameter D s 0.1 times the diameter D of the blunt precursor 5, the length L is 2 times the diameter D of the blunt precursor 5. The aerodynamic disk 2 and the shock needle 3 are processed by casting, 3D printing, extrusion molding, drawing processing, roll forming or laser cutting, and then polished, sprayed, chemically treated and the like to improve the dimensional accuracy and oxidation resistance and obtain good surface quality. The high-depth hole formed by the aerodynamic disk expansion half-angle section 1, the reverse flow guide 4.1 and the throttling control section 4.2 is obtained by electrical discharge machining, laser machining, chemical mechanical grinding and electrochemical machining. The slotting angle of the aerodynamic disk expansion half-angle section 1 is 45°, the diameter D of the reverse flow guide 4.1 and the throttling control section 4.2 o 0.05 times the diameter D of the blunt precursor 5. After the deep hole formed by the aerodynamic disk expansion half-angle section 1, the reverse flow guide 4.1 and the throttling control section 4.2 is processed, quality control and performance verification are carried out: first, ensure the smoothness and flatness of the hole wall, and improve the surface quality by polishing, chemical treatment and the like; second, accurately measure the size parameters (hole diameter, hole depth, hole position, hole inclination and hole surface roughness, etc.) of the deep hole to ensure that the requirements are met; then remove burrs, clean the hole thoroughly by cleaning and the like, and perform surface treatment on the hole wall to improve wear resistance and corrosion resistance. The shock needle 3 and the upstream portion 5.1 of the blunt precursor can be connected by mechanical connection, welding and bonding. The elongated cylindrical rod-shaped shock needle 3 is installed at the leading edge stagnation point of the upstream portion 5.1 of the blunt precursor. Mechanical connection uses bolts, rivets and the like to firmly fix the shock needle 3 and the upstream portion 5.1 of the blunt precursor together. This connection has high reliability and is easy to disassemble and repair; welding connection can form a more integrated structure with high weld strength and good fatigue resistance; bonding connection uses high-performance structural adhesive to bond the shock needle 3 and the upstream portion 5.1 of the blunt precursor together, which has high connection strength and uniform stress distribution. The upstream portion 5.1 and the downstream portion 5.2 of the blunt precursor are obtained by casting, forging, die casting, 3D printing and the like, and then connected in a similar manner to the connection of the shock needle 3 and the upstream portion 5.1 of the blunt precursor. After connection, the blunt precursor wall flow guide 4.3, the blunt precursor wall jet exit section 4.4 and the jet working fluid inlet 6 are obtained. The wall thickness T of the upstream portion 5.1 of the blunt precursor is 0.1 times the diameter D of the blunt precursor 5, and the diameter D j 0.1 times the diameter D of the blunt precursor 5. The blunt precursor wall flow guide 4.3 is a ball head type hollow slot covering the upstream portion 5.1 of the blunt precursor; the blunt precursor wall jet exit section 4.4 is a ring-shaped nozzle, and the included angle θ r and θ lare 44° and 46°. After the pneumatic disc expansion half-angle section 1, the pneumatic disc 2, the shock needle 3, the flow channel 4, the blunt forebody 5 and the jet working medium inlet 6 are connected, the jet cooling working medium is sprayed from the jet working medium inlet 6,

[0029] The working method of the blunt forebody hypersonic flight drag reduction and heat reduction structure disclosed in the embodiment is as follows: the flow is compressed at the head of the shock needle 3 to form a detached bow shock, and then the bow shock is converted into a leading edge oblique shock, and the reverse jet pushes the bow shock away from the head of the shock needle 3; the flow separates at the shoulder of the pneumatic disc 2, and then reattaches on the shock needle 3, and a vortex structure and a reattachment shock are generated behind the pneumatic disc 2; the flow flows downstream along the shock needle 3, and due to the influence of the adverse pressure gradient, the flow separates on the shock needle 3 to form a shear layer and a separation shock. Downstream of the flow separation point of the shock needle 3, the shock needle 3, the shear layer and the upstream part 5.1 of the blunt forebody form a conical recirculation zone. Due to the introduction of the shoulder jet, the reattachment of the shear layer to the blunt forebody 5 generates a reattachment shock, which is converted into a reattachment shock generated by the interaction of the shoulder jet and the flow. In the shock needle-flow channel-jet combination configuration, the flow direction changes after the reattachment shock, and is parallel to the shoulder jet Mach disc two. The shock needle-flow channel-jet combination configuration separates the flow on the shock needle 3 in advance, and the recirculation zone formed is significantly larger than that of the pure shock needle configuration, which makes the upstream part 5.1 of the blunt forebody and the downstream part 5.2 of the blunt forebody be wrapped in the recirculation zone in a larger range, and the high-temperature gas compressed by the bow shock and the leading edge shock is isolated outside and cannot directly heat the upstream part 5.1 of the blunt forebody and the downstream part 5.2 of the blunt forebody. Since the shoulder jet is located in the reattachment area of the shear layer, the shear layer cannot reattach to the original position in the shock needle-flow channel-jet combination configuration. By observing the shoulder jet, it can be found that due to the effect of the flow, the back pressure on both sides of the shoulder jet is different, which causes the shoulder jet to tilt downstream; due to the stagnation effect of the Mach disc two and the barrel-shaped shock two of the shoulder jet and the flow, small recirculation zones are formed on both sides of the shoulder jet. The blunt forebody hypersonic flight drag reduction and heat reduction structure realizes the drag reduction and heat reduction effect on the upstream part 5.1 of the blunt forebody and the downstream part 5.2 of the blunt forebody by controlling the wave structure, injecting the cooling working medium and fluid-structure coupling heat exchange.

[0030] In addition, the present application can also be designed as other similar structures, for example, the reverse flow guide 4.1 is designed as a Laval nozzle to reduce the total pressure loss, the angle θ of the aerodynamic disc expansion half-angle section 1 is set to 70°, the push-off effect of the reverse jet on the bow shock is enhanced, and the drag reduction and heat reduction effect is further improved. The wall thickness of the upstream part 5.1 of the blunt body should be as thin as possible under the consideration of the structural strength to enhance the heat exchange performance, and the opening angle and jet direction of the jet outlet section 4.4 of the blunt body wall surface are designed to further improve the drag reduction and heat reduction performance. A aerodynamic disc is added in the middle of the shock needle 3, which can also continue to improve the drag reduction and heat reduction performance.

[0031] The specific description described above further details the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A hypersonic flight drag reducing and heat protecting structure for a blunt forebody vehicle, characterized by: It includes pneumatic disc expansion half angle section (1), pneumatic disc (2), shock wave needle (3), flow channel (4), blunt precursor (5) and jet working medium inlet (6); the flow channel (4) includes: reverse guide channel (4.1), throttle control section (4.2), blunt precursor wall surface guide channel (4.3), blunt precursor wall surface jet exit section (4.4); the blunt precursor (5) includes blunt precursor upstream portion (5.1) and blunt precursor downstream portion (5.2); pneumatic disc (2) and shock wave needle (3) are connected, wherein the shock wave needle (3) is an equal-section slender cylindrical rod; the pneumatic disc expansion half angle section (1), reverse guide channel (4.1) and throttle control section (4.2) form high-depth-hole ratio deep hole; the shock wave needle (3) and the blunt precursor upstream portion (5.1) are connected and fixed, the equal-section slender cylindrical rod-shaped shock wave needle (3) is installed at the stagnation point of the leading edge of the blunt precursor upstream portion (5.1); the blunt precursor upstream portion (5.1) and the blunt precursor downstream portion (5.2) are connected and fixed, after the connection, the blunt precursor wall surface guide channel (4.3), the blunt precursor wall surface jet exit section (4.4) and the jet working medium inlet (6) are obtained; the blunt precursor wall surface guide channel (4.3) is a ball head type air slot covering the blunt precursor upstream portion (5.1); the blunt precursor wall surface jet exit section (4.4) is a ring-shaped nozzle.

2. A blunted forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as recited in claim 1, characterized by: After the aerodynamic disk expansion half-angle section (1), the aerodynamic disk (2), the shock wave needle (3), the flow channel (4), the blunt precursor (5) and the jet working medium inlet (6) are connected by machining, the jet cooling working medium is sprayed from the jet working medium inlet (6), and the cooling working medium flows from right to left; when flowing through the throttling control section (4.2), the jet cooling working medium is divided into two parts, one part flows to the reverse flow guide channel (4.1), and the other part flows to the blunt precursor wall surface flow guide channel (4.3); for the reverse jet, due to the sudden change of the cross section of the throttling control section (4.2), the reverse jet is decelerated to subsonic speed, the pressure is continuously increased, and as the reverse jet flows in the reverse flow guide channel (4.1), the reverse jet is continuously accelerated, and at the end of the reverse flow guide channel (4.1), the reverse jet is accelerated to supersonic speed, in order to further increase the jet speed of the reverse jet, the designed aerodynamic disk expansion half-angle section (1) has a flow channel expansion effect, can accelerate supersonic flow, and forms a Mach disk and a barrel shock wave; for the jet on the shoulder of the blunt precursor, due to the sudden change of the cross section of the throttling control section (4.2), part of the cooling working medium is divided into the blunt precursor wall surface flow guide channel (4.3), a series of compression waves are formed due to the throttling effect of the throttling control section (4.2), the jet cooling working medium is decelerated to subsonic speed after passing through the compression waves, and continues to flow in the blunt precursor wall surface flow guide channel (4.3); due to the flow channel expansion effect caused by the change of the geometric shape, a series of expansion waves are formed, the pressure of the cooling working medium is reduced after passing through the expansion waves, and due to the blocking effect near the blunt precursor wall surface jet outlet section (4.4), a reverse pressure gradient is formed in the blunt precursor wall surface flow guide channel (4.3), flow separation occurs near the left side channel, a very thin shear layer and a vortex structure are formed, and due to the large internal and external pressure difference of the blunt precursor wall surface jet outlet section (4.4), a highly under-expanded shoulder jet is formed, including a barrel shock wave two and a Mach disk two; the reverse jet and the shoulder jet have the effects of flow field reconstruction and adding cooling working medium, the reverse jet pushes away the arc-shaped shock wave in front of the aerodynamic disk (2) away from the aerodynamic disk (2); the shoulder jet makes the shear layer on the shock wave needle (3) away from the wall surface, moves the position where the shear layer reattaches to the wall surface of the blunt precursor (5) downstream, expands the recirculation zone in front of the blunt precursor (5), weakens the shock wave-shock wave interaction in front of the blunt precursor (5), reduces the intensity of the reattached shock wave, and moves the reattached shock wave away from the blunt precursor (5); at the same time, the cooling working medium in the reverse flow guide channel (4.1) and the blunt precursor wall surface flow guide channel (4.3) can also cool the incoming flow through the solid wall surface of the shock wave needle (3) and the upstream part (5.1) of the blunt precursor, and reduce the thermal load of the structure.

3. A blunted forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as recited in claim 2, characterized by: The aerodynamic disk (2) and the shock wave needle (3) are processed by casting, 3D printing, extrusion molding, drawing, rolling forming or laser cutting, and are subjected to grinding and polishing, spraying, chemical treatment; The high-depth-hole and deep hole formed by the aerodynamic disk expansion half-angle section (1), the reverse flow guide channel (4.1) and the throttling control section (4.2) are obtained by electric spark machining, laser machining, chemical mechanical grinding and electrochemical machining; After the deep hole machining of the aerodynamic disk expansion half-angle section (1), the reverse flow guide channel (4.1) and the throttle control section (4.2) is completed, quality control and performance verification are carried out: firstly, the hole wall smoothness and flatness are ensured, and polishing and chemical treatment can improve the surface quality; secondly, the size parameters of the deep hole are accurately measured to ensure that they meet the preset requirements; then, burrs are removed, the hole is cleaned by cleaning, and the hole wall is surface treated; the size parameters include hole diameter, hole depth, hole position, hole inclination and hole surface roughness; The shock needle (3) and the blunt forebody upstream portion (5.1) are connected by mechanical connection, welding or bonding; The blunt forebody upstream portion (5.1) and the blunt forebody downstream portion (5.2) are obtained by casting, forging, die casting or 3D printing respectively, and then connected by mechanical connection, welding or bonding.

4. A blunted forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as claimed in claim 1, wherein: The incoming flow is strongly compressed at the head of the shock needle (3) to form a detached bow shock, and then the bow shock is converted into a leading edge oblique shock, and the reverse jet pushes the bow shock away from the head of the shock needle (3); the flow separation occurs at the shoulder of the aerodynamic disk (2), and then the flow reattaches on the shock needle (3), and a vortex structure and an upstream reattachment shock are generated behind the aerodynamic disk (2); the incoming flow flows downstream along the shock needle (3), and due to the influence of adverse pressure gradient, flow separation occurs on the shock needle (3), forming a shear layer and a separation shock; downstream of the flow separation point of the shock needle (3), the shock needle (3), the shear layer and the blunt forebody upstream portion (5.1) form a conical-shaped recirculation zone; due to the above-mentioned shoulder jet injection, the original shear layer reattaches to the blunt forebody (5) to generate a reattachment shock, which is converted into a reattachment shock generated by the interaction between the shoulder jet and the incoming flow; In the shock needle-flow guide channel-jet combined configuration, the flow direction of the incoming flow changes after passing through the reattachment shock, and is parallel to the shoulder jet Mach disk two; compared with the pure shock needle configuration, the flow separation of the shock needle-flow guide channel-jet combined configuration occurs earlier, and the recirculation zone formed is significantly larger, so that the blunt forebody upstream portion (5.1) and the blunt forebody downstream portion (5.2) of the shock needle-flow guide channel-jet combined configuration are wrapped in a larger range by the recirculation zone, and the high-temperature gas compressed by the bow shock and the leading edge shock is isolated outside and cannot directly heat the blunt forebody upstream portion (5.1) and the blunt forebody downstream portion (5.2); due to the location of the shoulder jet in the reattachment area of the shear layer, the shear layer cannot reattach to the original position in the shock needle-flow guide channel-jet combined configuration; for the shoulder jet, due to the effect of the incoming flow, the back pressure on both sides of the shoulder jet is different, causing the shoulder jet to tilt downstream; due to the Mach disk two and the barrel-shaped shock two of the shoulder jet and the stagnation effect of the incoming flow, small vortex structures are formed on both sides of the shoulder jet; the blunt forebody aircraft hypersonic flight drag reduction and heat reduction structure realizes the drag reduction and heat reduction effect of the blunt forebody upstream portion (5.1) and the blunt forebody downstream portion (5.2) by controlling the wave structure, injecting cooling working medium and fluid-structure coupling heat exchange medium.

5. A blunt forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as claimed in claim 1, 2 or 3 wherein: The diameter D of the aerodynamic disc (2) d is set to 0.2-0.5 times the diameter D of the blunt nose (5); The diameter D of the aerodynamic disc (2) d is set to 0.3 times the diameter D of the blunt nose (5); The length L of the shock needle (3) is set to 0.5-2 times the diameter D of the blunt forebody (5); The length L of the shock wave needle (3) is set to be 2 times of the diameter D of the blunt forebody (5); The aerodynamic disk (2) is provided with an aerodynamic disk expansion half-angle section (1) and a reverse flow guide channel (4.1) for discharging reverse jet flow, the reverse flow guide channel (4.1) is designed as a Laval nozzle, and the angle θ of the aerodynamic disk expansion half-angle section (1) is set to be 0-70°.

6. A blunted forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as claimed in claim 5 wherein: The angle θ of the aerodynamic disk expansion half-angle section (1) is set to be 70°.

7. A blunt forebody hypersonic vehicle high speed flight drag reducing and heat protecting structure as claimed in claim 1, 2 or 3 wherein: The aerodynamic disk (2) is chamfered at the sharp corner part.

8. A blunt forebody hypersonic vehicle high speed flight drag reducing and heat protecting structure as claimed in claim 1, 2 or 3 wherein: The wall thickness T of the blunt forebody upstream part (5.1) is set to be 0.1-0.2 times of the diameter D of the blunt forebody (5), and the opening of the blunt forebody wall flow guide channel (4.3) is designed as a Laval nozzle.

9. A blunted forebody hypersonic vehicle high speed flight drag reducing and heat shielding structure as claimed in claim 8 wherein: The wall thickness T of the blunt forebody upstream part (5.1) is set to be 0.1 times of the diameter D of the blunt forebody (5).

10. A blunt forebody hypersonic vehicle high speed flight drag reducing and heat protecting structure as claimed in claim 1, 2 or 3 wherein: Diameter D of throttling control section (4.2) o Set to 0.5-0.8 times of diameter D of jet working medium inlet (6) j Further improve the effect of drag reduction and heat reduction by proportionally controlling the reverse jet and shoulder jet of the cooling working medium flow.

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