CN115258130A

CN115258130A - Hypersonic speed combination drag reduction and heat reduction structure based on reverse jet flow and active cooling

Info

Publication number: CN115258130A
Application number: CN202210924988.5A
Authority: CN
Inventors: 王战; 李佳伟; 张安坤; 沈煊; 李宪开; 周勇健; 何墨凡; 盛发家
Original assignee: Shenyang Aircraft Design Institute Yangzhou Collaborative Innovation Research Institute Co ltd
Current assignee: Shenyang Aircraft Design Institute Yangzhou Collaborative Innovation Research Institute Co ltd
Priority date: 2022-08-03
Filing date: 2022-08-03
Publication date: 2022-11-01

Abstract

Hypersonic speed combination drag reduction heat reduction structure based on reverse jet and active cooling belongs to drag reduction heat reduction technical field. And arranging the nozzles at the passivated front edge of the airplane to implement reverse jet flow. The nozzles are symmetrically arranged up and down relative to the central line of the passivated front edge of the airplane in a matrix form. A convection cooling loop, a gas jet flow loop and an internal supporting space are arranged in the passivated front edge of the airplane; the convection cooling loop is respectively arranged on the upper surface and the lower surface of the passivation front edge, the cross section of a flow channel at one end of the convection cooling loop close to the nozzle is in a step shape, and a cooling medium is circulated in the convection cooling loop through a pump; one end of the gas jet flow loop is connected with the nozzle, the other end of the gas jet flow loop is connected with the internal jet flow device, gas sprayed by the internal jet flow device is sprayed out of the nozzle through the gas jet flow loop, the gas jet flow loops are respectively positioned on the upper side and the lower side of the central line, and the gas jet flow loops are gradually inclined towards the central line from the internal jet flow device to the nozzle. The invention realizes the reduction of the strong heating heat flow of the passivated front edge area of various aircrafts caused by shock wave-shock wave interference.

Description

Hypersonic speed combination drag reduction heat reduction structure based on reverse jet flow and active cooling

Technical Field

The invention relates to a hypersonic combined resistance-reducing and heat-reducing technology based on reverse jet flow and active cooling, and belongs to the technical field of resistance reduction and heat reduction. The method is suitable for reducing the strong heating phenomenon generated by the interaction of III-type and IV-type shock waves on the front edge of the fairing of the scramjet engine.

Background

The rapid development of hypersonic aircraft presents many challenges to designers. High pressure and heating phenomena occur in the region of the aircraft subjected to the shock waves during flight. Typical areas of interest are the wing, empennage, control surface compression angle, and axial angle regions at the wing/fuselage surface junction. For air-breathing aircraft, the problem of aerodynamic heating of the leading edge of the engine fairing is of particular concern because of the need to maximise engine thrust by maximising air capture, and the shock waves can generate extremely high pressures and heat at the leading edge of the fairing, depending on their intersection with the impingement of the fairing bow. Peak pressure and heating also depend on mach number, reynolds number, gas composition and impact strength.

Edney originally recorded six fundamental shock interaction modes, and he conducted shock interaction experiments at mach 4.6 and discussed the interactions in detail. The leading edge schematic shows the approximate angular regions and types of interaction modes that result when a weakly oblique shock interacts with a leading edge bow shock. Three of the interaction types (I, II and V) result in shock wave/boundary layer interactions. Type III interactions result in high local pressure and heating of the attached shear layer, depending on the state of the impinging shear layer. Type VI interactions result in expansion fan/boundary layer interactions. The most severe type of shock interaction is the type IV interaction, which produces a supersonic jet impacting the leading edge when oblique shocks intersect near the normal portion of the bow shock. The maximum pressure and heating rate occurs when the jet impinges perpendicular to the leading edge surface.

Designing a cowl leading edge to withstand such intense heating is a difficult task. The heating rate gradient that occurs over the narrow type IV interaction region 1,6 results in a larger wall temperature gradient, resulting in greater thermal stress. Type IV interactions are generally unstable, creating oscillatory thermal stresses that limit the useful life of the leading edge. Experimental studies on a cylindrical leading edge model with mach number 8 show that the swept edge reduces the peak heat flux density of type IV interaction by a factor equal to the cosine of the sweep angle and raised to the power of 2.2. Glass found that scans at 15 and 30 ° reduced the peak heat flow by 7% and 27%, respectively.

Recent efforts to mitigate type IV interaction heating have focused on controlling impact interactions using various techniques. The Gaitonde computational study focuses on the Magnetoaerodynamic (MGD) technique and examines several electromagnetic configurations. The most successful configuration is to apply a magnetic field (up to 7 tesla) to the mach 8 stream to propel the bow shock forward, causing the incident shock to interact with the bow shock at a slightly lower position, producing type III interaction that strikes the leading edge surface. Maximum surface heat load the reduction is 20%. The effect of laser-induced energy deposition in a mach number of 3.45 gas stream on type IV interaction was investigated by cadara. The simulated laser pulse energy was 160mJ, at various locations upstream of the interaction. The resulting high temperature region temporarily changes the local mach number, deforming the shock and moving toward the IV shock structure, temporarily increasing pressure and heating (about 10% and 20%, respectively). The high temperature zone then causes the bow shock to expand, temporarily changing the interaction, thereby reducing the impact pressure and heating (in about 10 microseconds).

A relatively simple way to mitigate shock interference heating is to inject fluid into the stagnation region of the leading edge. In an experiment conducted by Nowak, the effect of evaporative cooling on reducing surface heating by impingement was studied. Gaseous helium is injected at mach 12 velocity into most of the forward facing surface of the hemispherical handpiece. When the evaporation mass flow is 31% of the free flow mass flow, the peak heating is only reduced by 8%. Norwalk suggests that, in order to make the coolant more effective, the coolant should be injected locally in the shock wave interaction impact region. For type IV interaction, this is typically 20 ° below the leading edge centerline.

There have been many studies on injecting a fluid into a stagnation region without external impact interference. These studies indicate that fluid injection can significantly reduce aerodynamic heating and air resistance. Studies examining the jet flow structure without external impact disturbances show that larger impact displacements can be achieved. Bushnell and Huffman investigated the effect of forward jets of liquid water and liquid nitrogen on reducing radio attenuation in hypersonic flight at mach 8 and 19.5. They found that the penetration of liquid water is greatest and in most cases oblique shock waves are produced.

Prabhu conducted computational studies on the idea of locally injecting forward gas jets to alter type IV interactions, which simulated a Mach 8 flow disturbed by oblique shock waves upstream of the leading edge of a two-dimensional cylinder, with both the jet and the free flow consisting of air simulated as ideal gas with a constant specific heat ratio of 1.4. The ratio of jet mass flux to free stream mass flux was 0.337 (momentum ratio 0.253), where the area used to calculate free stream mass flux was the projected surface area of the cylinder. The gas jet injected the gas stream opposite the centerline of the leading edge (0) and the type IV supersonic jet (20). For both cases, the shock wave interaction was altered such that peak heating was reduced by about 30%, although in both cases the modified interaction appeared to impact the leading edge. They suggest the use of a more detailed computational grid to better quantify the heat transfer reduction and optimize the position and number of gas jets, jet mass flow and jet mach number.

In summary, injecting energy into the air stagnation region can effectively relieve aerodynamic heating and air resistance. However, the above studies have not taken into account the reverse jet structure and internal circuit arrangement, and have rarely taken into account the heat reduction effect on the downstream region of the passivation front. The hypersonic combined resistance-reducing and heat-reducing technology based on reverse jet flow and active cooling can realize larger shock wave displacement, weaken the shock wave-shock wave interference phenomenon, and ensure that the interaction between the shock waves can not interfere the surface of the leading edge, thereby reducing the severe aerodynamic thermal environment of the leading edge of an aircraft.

Disclosure of Invention

The invention adopts a hypersonic combined drag reduction and heat reduction technology based on reverse jet flow and active cooling, aiming at a high heat flow density area with serious local shock wave interference in an aviation and aerospace aircraft, and reduces strong heating heat flow generated by the passivation front edge of the aircraft due to shock wave-shock wave interference by arranging nozzles at the passivation front edge part and implementing reverse jet flow.

The technical scheme of the invention is as follows:

the hypersonic combined drag reduction and heat reduction structure based on reverse jet flow and active cooling arranges nozzles at the position of the passivated front edge of the airplane to implement reverse jet flow. The nozzles are arranged in a matrix form, and the arrangement of the nozzles is symmetrical up and down relative to the central line of the passivated front edge of the airplane; the section of the nozzle is rectangular.

A convection cooling loop, a gas jet flow loop and an internal supporting space are arranged inside the passivated front edge of the airplane; the convection cooling loop is respectively arranged on the upper surface and the lower surface of the passivation front edge, the cross section of a flow channel at one end of the convection cooling loop close to the nozzle is in a step shape, and a cooling medium is circulated in the convection cooling loop through a pump and is used for slowing down the flowing speed of a cooling fluid and enhancing the cooling effect; one end of the gas jet flow loop is connected with the nozzle, the other end of the gas jet flow loop is connected with the internal jet flow device, gas sprayed by the internal jet flow device is sprayed out of the nozzle through the gas jet flow loop, the gas jet flow loops are respectively positioned on the upper side and the lower side of the central line, and the gas jet flow loop is gradually inclined towards the central line from the internal jet flow device to the nozzle.

Further, the aircraft blunt leading edge cross-sectional shape is comprised of a small forward plane, a 45 ° arc, and a 45 ° plane.

Furthermore, the nozzles are divided into an upper group and a lower group, the two groups of nozzles are vertically and symmetrically arranged relative to the center line of the passivated front edge of the airplane, one group of nozzles is positioned above the center line of the passivated front edge of the airplane, the other group of nozzles is positioned below the center line of the passivated front edge of the airplane, and the nozzles are inclined towards the center line.

The invention has the beneficial effects that: the hypersonic combined resistance-reducing and heat-reducing technology based on reverse jet flow and active cooling can realize larger shock wave displacement, weaken the shock wave-shock wave interference phenomenon, and ensure that the interaction between the shock waves can not interfere the surface of the leading edge, thereby reducing the severe aerodynamic thermal environment of the leading edge of an aircraft.

Drawings

FIG. 1 is a first cross-sectional schematic view of a passivated front model.

FIG. 2 is a schematic view of a passivation front at a forward viewing angle.

FIG. 3 is a schematic cross-sectional view of a passivated leading edge model II.

Fig. 4 (a) is a sectional view a of fig. 1, fig. 4 (B) is a sectional view B of fig. 4 (a), fig. 4 (C) is a sectional view C of fig. 4 (a), and fig. 4 (D) is a sectional view D of fig. 4 (a).

FIG. 5 is a schematic cross-sectional view of a passivated leading edge model II.

Fig. 6 is a jet front flow field diagram.

Fig. 7 is a jet flow field diagram.

Fig. 8 is a wall temperature contrast diagram for a heat shield without heat shield/convection cooling.

Fig. 9 is a graph comparing typical temperature history.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are a part of embodiments of the present invention, but not all embodiments. Other embodiments, which can be derived by one of ordinary skill in the art from the embodiments of the present invention without creative efforts, are within the scope of the present invention.

A hypersonic combined resistance-reducing and heat-reducing technology based on reverse jet flow and active cooling is used for arranging nozzles at the position of a passivated front edge of an airplane and implementing reverse jet flow. The nozzles are arranged in a matrix as shown in fig. 1 and are composed of four exhaust body nozzles, wherein two rows are positioned above the center line of the model, and two rows are positioned below the center line of the model and inclined towards the center line. A convection cooling loop, a gas jet flow loop and an internal supporting space are arranged in the passivation front edge model; the convection cooling loops are respectively arranged on the upper surface and the lower surface of the passivation front edge, and the cross section of the flow channel is in a step shape and used for slowing down the flowing speed of cooling fluid and enhancing the cooling effect; the gas jet flow loops are respectively positioned at the upper side and the lower side of the central line, and the nozzle is rectangular and is inwards connected with the space of the internal jet flow device; the blunted leading edge cross-sectional shape is made up of a small forward flat, a 45 arc, and a 45 plane.

Through comparison of the fig. 6 and fig. 7, it is found that the hypersonic combined drag reduction and heat reduction technology based on reverse jet flow and active cooling can realize larger shock wave displacement and can achieve a shock wave-shock wave interference phenomenon, so that the interaction between shock waves can not interfere with the surface of the leading edge, and the severe aerodynamic thermal environment of the leading edge of the aircraft is reduced. From the aerodynamic force/heat comparison graph given in table 1, it can be seen that the hypersonic combined drag reduction and heat reduction technology based on the reverse jet and active cooling has great improvement on both aerodynamic force/heat.

TABLE 1

The convection cooling effect evaluation is carried out by adopting a numerical simulation method, and the comparison of the structure surface temperature shown in fig. 8 shows that the temperature of the two side wall surfaces of the convection cooling heat-proof structure is obviously higher than that of the wall surface without the heat-proof structure. Figure 9 also compares the temperature history of the leading edge point of the convection cooling heat protection structure, the location of the highest temperature point at the time of 100s and the leading edge point without the heat protection structure, in the early stage of pneumatic heating, the wall temperature of the convection cooling heat-proof structure is higher than that of the heat-proof structure.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the scope thereof; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. The hypersonic combined drag reduction and heat reduction structure based on reverse jet flow and active cooling is characterized in that nozzles are arranged at the position of a passivated front edge of an airplane to implement reverse jet flow; the nozzles are arranged in a matrix form, and the arrangement of the nozzles is symmetrical up and down relative to the central line of the passivated front edge of the airplane; the section of the nozzle is rectangular;

a convection cooling loop, a gas jet loop and an internal supporting space are arranged inside the passivated front edge of the airplane; the convection cooling loop is respectively arranged on the upper surface and the lower surface of the passivation front edge, the cross section of a flow channel at one end of the convection cooling loop close to the nozzle is in a step shape, and a cooling medium is circulated in the convection cooling loop through a pump and is used for slowing down the flowing speed of a cooling fluid and enhancing the cooling effect; one end of the gas jet flow loop is connected with the nozzle, the other end of the gas jet flow loop is connected with the internal jet flow device, gas sprayed by the internal jet flow device is sprayed out of the nozzle through the gas jet flow loop, the gas jet flow loops are respectively positioned on the upper side and the lower side of the central line, and the gas jet flow loop is gradually inclined towards the central line from the internal jet flow device to the nozzle.

2. A hypersonic combined drag reducing and heat rejection structure based on reverse jet and active cooling as claimed in claim 1 wherein said aircraft blunt leading edge cross sectional shape is comprised of a small forward plane, a 45 ° arc and a 45 ° plane.

3. The hypersonic combined drag reduction and heat reduction structure based on reverse jet flow and active cooling as claimed in claim 1 or 2, wherein the nozzles are divided into two groups, one group is located above the centerline of the aircraft passive leading edge, the other group is located below the centerline of the aircraft passive leading edge, and the nozzles are inclined to the centerline.