Resistance reduction and heat protection system and method for hypersonic flight vehicle

Abstract

The invention belongs to the field of hypersonic active flow control, and discloses a drag reduction and heat protection system and method for a hypersonic aircraft, and the method combines two active flow control methods of energy deposition and magnetofluid flow control. The excellent drag reduction characteristic of energy deposition can bring a good drag reduction effect to an aircraft, meanwhile, energy deposition can serve as an auxiliary ionization technology, and the magnetic control effect of magnetic fluid flow control is improved by improving the fluid conductivity; due to the outstanding thermal protection performance of magnetic fluid flow control, an excellent thermal protection effect is brought to the aircraft after heat flow increase in a part of time periods caused by the energy deposition process is treated; meanwhile, the problems of resistance impact and oscillation caused by pulse energy deposition are fully inhibited under the action of the magnetic field Lorentz force; by the adoption of the method, a better hypersonic speed drag reduction and heat protection effect is achieved, the resistance borne by the hypersonic speed aircraft can be effectively reduced, the heat protection capacity of the aircraft is improved, and the method has wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of hypersonic active flow control, and in particular relates to a drag reduction and heat protection system and method for a hypersonic aircraft. Background Art

[0002] Hypersonic vehicles face two most severe challenges when flying at extremely high speeds: huge drag and strong aerodynamic heating. Huge shock wave drag will significantly increase the energy consumption of the vehicle, thereby affecting the flight time and range of the vehicle; strong aerodynamic heating causes the surface temperature of the vehicle to rise sharply, leading to softening and ablation of the material. These two problems not only limit the flight performance of the aircraft, but also pose a serious threat to its structural integrity and flight stability. Therefore, the design and development of efficient drag reduction and thermal protection systems are key technologies in this field.

[0003] Hypersonic flow control technology is widely used in drag reduction and heat protection, mainly including passive flow control and active flow control. Among them, passive flow control does not require external energy input and relies on fixed geometric shapes or material properties to affect the flow. Its structure is relatively simple and reliable, but its control effect may fail when the flight conditions deviate from the design conditions. Active flow control is to directly apply appropriate disturbance patterns in the flow field of the object and couple with the inherent pattern of the flow to achieve flow control. It can be adjusted in real time according to the flight conditions, with high flexibility and strong applicability. For hypersonic cruise vehicles, their drag and aerodynamic thermal environment have the characteristics of high magnitude, long duration, and complex and changeable. Passive flow control methods are difficult to meet their drag reduction and heat protection requirements. Therefore, active flow control methods are the preferred choice for hypersonic aircraft drag reduction and heat protection design.

[0004] Currently, active flow control methods usually use energy deposition methods, which can achieve excellent drag reduction effects; however, the energy deposition method introduces high energy into the flow field, which will cause the aircraft to have problems with heat flow growth during certain periods of time; at the same time, for the mainstream energy deposition using pulse excitation, its drag reduction process still has certain large impact problems and resistance oscillation characteristics.

[0005] It can be seen that the use of existing drag reduction and heat protection measures for hypersonic aircraft is likely to lead to an increase in heat flow and produce large shocks and drag oscillations, affecting the stability of the aircraft. Summary of the invention

[0006] The present invention provides a drag reduction and heat protection system and method for a hypersonic aircraft, so as to solve the technical problem that the existing drag reduction and heat protection measures for hypersonic aircraft easily lead to the increase of heat flow and the generation of large impact and drag oscillation phenomenon.

[0007] In order to achieve the above object, the present invention adopts the following technical contents: In a first aspect, the present invention provides a method for reducing drag and protecting heat of a hypersonic aircraft, comprising: Based on the laser excitation method, the laser is emitted and focused in front of the hypersonic vehicle for energy deposition; A magnetic field is generated around a hypersonic vehicle, and a Lorentz force is exerted on the flow field to achieve magnetohydrodynamic flow control of the fluid in the flow field.

[0008] Further, Among them, the magnetofluid flow control of the fluid in the flow field is first performed by applying the Lorentz force; After the hypersonic steady-state flow field is formed, energy deposition is carried out.

[0009] Further, The magnetic fluid flow control process and the energy deposition process are carried out simultaneously.

[0010] Further, The applied Lorentz force satisfies the following conditions: The applied Lorentz force has two components, one component is opposite to the flow direction and is used to reduce the flow velocity; the other component is perpendicular to the flow direction and is used to increase the shock wave separation distance and reduce the shock wave drag.

[0011] Furthermore, the aerodynamic force exerted on the hypersonic aircraft is changed by adjusting the position of energy deposition and the direction of the magnetic field, thereby adjusting the attitude and flight trajectory of the hypersonic aircraft.

[0012] Furthermore, the generated magnetic field adopts a dipole-like magnetic field layout.

[0013] Further, The dipole-like magnetic field layout meets the following conditions:

[0014] In the formula, B The magnetic field is x , y , z A vector consisting of intensity components in three directions; B 0 is the magnetic field strength at the stationary point; r b is the radius of the hemisphere of the hypersonic vehicle.

[0015] Further, The energy deposition parameters in the energy deposition process are adjusted according to the flight conditions of the hypersonic aircraft; the energy deposition parameters include deposition position, deposition center area size, laser energy and laser pulse width.

[0016] In a second aspect, the present invention provides a drag reduction and heat protection system for a hypersonic aircraft, which is used to implement the above-mentioned drag reduction and heat protection method for a hypersonic aircraft, and includes a pulsed laser generator and a magnetic field generating device; The pulse laser generator is arranged at the head of the hypersonic aircraft, and is used to emit laser light and focus it in front of the hypersonic aircraft, so as to perform energy deposition; The magnetic field generating device is connected to the hypersonic aircraft and is used to generate a magnetic field around the hypersonic aircraft, and to achieve magnetofluid flow control of the fluid in the flow field by applying Lorentz force to the flow field.

[0017] Furthermore, the pulse laser generator and the magnetic field generating device are both arranged inside the hypersonic vehicle.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for drag reduction and heat protection of a hypersonic aircraft, which combines two active flow control methods, energy deposition and magnetofluid flow control. The excellent drag reduction characteristics of energy deposition can bring good drag reduction effects to the aircraft. At the same time, energy deposition can be used as an auxiliary ionization technology to improve the magnetic control effect of magnetofluid flow control by increasing fluid conductivity. The outstanding thermal protection performance of magnetofluid flow control brings excellent heat protection effects to the aircraft after dealing with the heat flow growth in some periods caused by the energy deposition process. At the same time, the effect of the Lorentz force of the magnetic field fully suppresses the resistance impact and oscillation problems caused by pulse energy deposition. The method is used to achieve better hypersonic drag reduction and heat protection effects, can effectively reduce the resistance of hypersonic aircraft and improve the thermal protection capability of the aircraft, and has broad application prospects.

[0019] Preferably, in the present invention, the flow of the magnetic fluid is first controlled by the Lorentz force to form a stable flow field, and then energy deposition is performed; this sequential control method makes the effect of the magnetic fluid flow control on the suppression of the resistance and heat flow peak more significant, further improving the drag reduction and heat protection effects.

[0020] Preferably, in the present invention, the magnetic fluid flow control and energy deposition process are carried out simultaneously, which can realize dynamic regulation of the flow field; in this way, it can more flexibly cope with various complex situations that may arise during the flight process; and the effect of the magnetic fluid flow control suppresses the peak values ​​of the resistance and heat flow to a certain extent, ensuring the drag reduction and heat protection effects.

[0021] Preferably, in the present invention, by precisely controlling the direction and magnitude of the applied Lorentz force, precise control of the fluid velocity and direction in the flow field can be achieved; this control method not only helps to reduce the resistance and heat load of the aircraft, but also optimizes the aerodynamic performance of the aircraft by adjusting the shock wave separation distance; at the same time, it also helps to improve the stability and controllability of the aircraft.

[0022] Preferably, in the present invention, the aerodynamic force exerted on the hypersonic aircraft is changed by adjusting the position of energy deposition and the direction of the magnetic field, thereby adjusting the attitude and flight trajectory of the hypersonic aircraft; that is, by adjusting the output energy of the energy deposition laser and the applied magnetic field strength, and controlling the combination timing of the two methods, the optimal drag and heat flow reduction of the hypersonic aircraft can be achieved.

[0023] Preferably, in the present invention, a dipole-like magnetic field layout is used to produce a more uniform and stable magnetic field environment, which helps to achieve precise control of the fluid in the flow field; this layout not only improves the efficiency and effect of magnetic fluid flow control, but also helps to reduce energy consumption and costs.

[0024] Preferably, in the present invention, adjusting the energy deposition parameters according to the flight conditions can ensure that the best drag reduction and heat protection effects can be obtained in different flight phases; this dynamic control method not only improves the adaptability and flexibility of the aircraft, but also helps to reduce energy consumption and costs; at the same time, it also helps to improve the reliability and safety of the aircraft.

[0025] The present invention also provides a drag reduction and heat protection system for a hypersonic aircraft, which is used to implement the above-mentioned drag reduction and heat protection method for a hypersonic aircraft. The system includes a pulsed laser generator and a magnetic field generating device; the pulsed laser generator can emit laser and focus on the front of the hypersonic aircraft to perform energy deposition; a high-energy plasma is formed in the deposition area, and the shock wave formed by the expansion of the plasma area interacts with the bow shock wave at the head of the aircraft to improve the flow field structure and shock wave structure in front of the aircraft, thereby achieving an excellent drag reduction effect; the magnetic field generating device generates a magnetic field around the hypersonic aircraft, and utilizes the interaction between the conductive fluid and the magnetic field when flowing in the magnetic field to control the flow of the fluid in the flow field and achieve an excellent heat protection effect; the combination of the two improves the magnetic control effect of the magnetic fluid flow control by improving the fluid conductivity; the effect of the Lorentz force of the magnetic field fully suppresses the resistance impact and oscillation problems caused by the pulse energy deposition; the respective advantages are brought into play and the respective deficiencies are made up, and the use of the system achieves a better hypersonic drag reduction and heat protection effect.

[0026] Preferably, in the present invention, the pulse laser generator and the magnetic field generating device are both arranged inside the aircraft, so that the system has the advantages of being controllable, stable, and not changing the aerodynamic shape of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A logic schematic diagram of a method for reducing drag and protecting heat of a hypersonic aircraft provided by an embodiment of the present invention; Figure 2 A schematic diagram of a model of a drag reduction and heat protection system for a hypersonic aircraft provided in an embodiment of the present invention; Figure 3 A schematic diagram comparing the time distribution of normalized aerodynamic drag of a bluff body under three working conditions provided by an embodiment of the present invention; Figure 4 A comparative schematic diagram of the time distribution of the total heat flux on the bluff body wall under three working conditions provided in an embodiment of the present invention.

[0028] Reference numerals: 1. Hypersonic vehicle blunt body geometry model; 2. Magnetic field generator; 3. Pulsed laser generator; 4. Energy deposition center. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0033] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0035] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] As mentioned in the background technology, currently, active flow control methods usually use energy deposition methods, which can achieve excellent drag reduction effects; however, the energy deposition method introduces high energy into the flow field, which will cause the aircraft to have problems with heat flow growth during certain periods of time; at the same time, for the mainstream energy deposition using pulse excitation, its drag reduction process still has certain large impact problems and resistance oscillation characteristics.

[0037] In addition, although the use of magnetic fluid flow control can increase the shock wave separation distance and reduce the shock wave resistance, when this method is used for drag reduction and heat protection, it will face the problem that when the magnetic field intensity is large, the reaction force of the Lorentz force will bring a certain increase in the total resistance of the aircraft.

[0038] In order to solve the above problems, the present embodiment provides a method for reducing drag and protecting against heat of a hypersonic aircraft. The method can solve the problems of huge aerodynamic drag and severe aerodynamic heating faced by hypersonic aircraft.

[0039] In order to facilitate further understanding of this technical solution, the following technical terms are explained: ED (Energy Deposition): Energy deposition; MHD (Magneto Hydrodynamic): magnetohydrodynamics; ED without MHD – energy deposition only; ED and MHD – energy deposition and MHD flow control are applied simultaneously; ED after MHD – energy deposition is applied after MHD flow control is stabilized.

[0040] like Figure 1 As shown, this embodiment provides a method for reducing drag and protecting heat of a hypersonic aircraft, comprising the following steps: Based on the laser excitation method, the laser is emitted and focused in front of the hypersonic vehicle for energy deposition; A magnetic field is generated around a hypersonic vehicle, and a Lorentz force is exerted on the flow field to achieve magnetohydrodynamic flow control of the fluid in the flow field.

[0041] As a preferred embodiment, the magnetic fluid flow control can be performed on the fluid in the flow field by applying the Lorentz force first; after the hypersonic steady-state flow field is formed, energy deposition can be performed. The magnetic fluid flow control is performed first by the Lorentz force, and after the stable flow field is formed, energy deposition can be performed; this sequential control method makes the magnetic fluid flow control more effective in suppressing the drag and heat flow peaks, further improving the drag reduction and heat protection effects.

[0042] As a preferred embodiment, the magnetic fluid flow control and energy deposition process can also be carried out simultaneously to achieve dynamic regulation of the flow field; in this way, it can more flexibly cope with various complex situations that may arise during the flight; and the effect of magnetic fluid flow control can suppress the peak values ​​of resistance and heat flow to a certain extent, ensuring the drag reduction and heat protection effects.

[0043] In this embodiment, the problem of heat flow growth in some periods of time during the drag reduction process of energy deposition is effectively solved, and the drag oscillation and impact behavior caused by pulse energy deposition are suppressed. When the aircraft flies at hypersonic cruising, it will face huge shock wave drag and severe aerodynamic heating. To this end, firstly, the high-energy laser energy is focused at a certain position in front of the aircraft by means of a pulsed laser generator, and the shock wave induced by energy deposition is used to interact with the bow shock wave at the head of the aircraft to improve the flow field and shock wave structure in front of the aircraft, thereby achieving excellent drag reduction effect. At the same time, considering the thermochemical non-equilibrium effect of hypersonic flow and energy deposition as an auxiliary ionization method to improve the fluid conductivity, during the energy deposition process, by starting the magnetic field generating device inside the aircraft at an appropriate time, the interaction between the conductive fluid and the magnetic field when flowing in the magnetic field is used to achieve effective control of the fluid flow and achieve excellent heat protection effect, while suppressing the drag oscillation and impact behavior caused by pulse energy deposition. The present invention can flexibly adjust the energy output of the energy deposition laser and the applied magnetic field strength according to the flight conditions, control the combination timing of the two methods, and thus achieve the best drag and heat flow reduction of the aircraft under different conditions. By changing the energy deposition position and the direction of the magnetic field generator, the aerodynamic force on the aircraft can be changed, thereby achieving effective adjustment of the aircraft's attitude and flight trajectory. In addition, since the pulse laser generator 3 and the magnetic field generating device 2 can be arranged inside the hypersonic aircraft, this method has the advantages of being controllable, stable, and not changing the aerodynamic shape of the hypersonic aircraft.

[0044] Combination Figure 2 As shown, energy deposition adopts pulsed laser excitation. Appropriate energy deposition parameters are selected according to the flight conditions of the hypersonic aircraft, mainly including deposition position, deposition center area size, laser energy, laser pulse width, etc. The pulsed laser generator 3 installed at the head of the hypersonic aircraft emits laser and focuses on a position in front of the aircraft for energy deposition. A high-energy plasma is formed at the energy deposition center 4. The shock wave formed by the expansion of the plasma area interacts with the bow shock wave at the head of the aircraft to improve the flow field structure and shock wave structure in front of the aircraft, thereby achieving an excellent drag reduction effect.

[0045] In this embodiment, the magnetic fluid flow control is achieved by installing a magnetic field generating device 2 inside the aircraft, and the magnetic field layout generated by the device is a dipole-like magnetic field. The interaction between the conductive fluid and the magnetic field when flowing in the magnetic field is utilized to control the flow of the fluid in the flow field and achieve an excellent heat protection effect. The distribution of the Lorentz force applied to the flow field by the magnetic fluid flow control satisfies the following conditions: the Lorentz force has two components, one component is opposite to the flow direction, which reduces the flow velocity and greatly reduces the aerodynamic heating caused by air compression and viscosity, and the other component is perpendicular to the flow direction, which increases the shock wave separation distance and reduces the shock wave resistance. At the same time, the thermal environment of the aircraft surface is improved due to the distance away from the high-temperature shock wave layer.

[0046] The combination of energy deposition and magnetic fluid flow control is changed according to the flight conditions of the hypersonic aircraft. According to the drag characteristics and heat flow distribution characteristics, the proportion of the combination of the two methods is optimized, that is, the energy deposition laser output energy and the applied magnetic field strength are adjusted, and the combination timing of the two methods is controlled to achieve the best drag and heat flow reduction of the hypersonic aircraft.

[0047] In this example, energy deposition is characterized by adding an energy source term to the energy equation. The energy density (energy per unit volume per unit time) of laser energy deposition satisfies:

[0048] In the formula, x 0, y 0, z 0 indicates the center position of energy deposition; R x , R y , R z is the radius of the deposition area in three directions; ρ is the flow field density; g ( t ) is a step function, representing the on and off of the laser pulse;

[0049] In the formula, τ is the pulse width of the laser; characteristic parameter of energy deposition q 0 Satisfied

[0050] In the formula, Q L The laser output energy is the laser energy deposition; η is the efficiency of the deposition energy being absorbed by the air; V 0 is the volume of the laser energy deposition area.

[0051] In this embodiment, the magnetic field generating device is essentially a group of energized coils, which generates dipole-like magnetic fields of different magnetic field strengths by controlling the magnitude of the current flowing through the coils, wherein the dipole-like magnetic field layout satisfies the following conditions:

[0052] In the formula, B The magnetic field is x , y , z A vector consisting of intensity components in three directions; B 0 is the magnetic field strength at the stationary point; r b is the radius of the hemisphere of the hypersonic vehicle.

[0053] Furthermore, in this embodiment, the two-dimensional form of the dipole-like magnetic field layout satisfies the following conditions:

[0054] In the formula, B 0 is the magnetic field strength at the stationary point, which is controlled by the magnitude of the current flowing through the magnetic field generating device 2. B The value of 0 represents the difference in the strength of the magnetic field applied by the device; B x , B y The magnetic field is x , y Intensity components in two directions; r b is the radius of the hemisphere of the hypersonic vehicle.

[0055] The present embodiment also provides a drag reduction and heat protection system for a hypersonic aircraft, which can implement the above-mentioned drag reduction and heat protection method for a hypersonic aircraft, and includes a pulse laser generator 3 and a magnetic field generating device 4; wherein the pulse laser generator 3 is arranged at the head of the hypersonic aircraft, and is used to emit laser and focus on the front of the hypersonic aircraft, so as to perform energy deposition; the magnetic field generating device 4 is connected to the hypersonic aircraft, and is used to generate a magnetic field around the hypersonic aircraft, and to achieve magnetofluid flow control of the fluid in the convection field by applying Lorentz force to the convection field.

[0056] In this embodiment, the pulse laser generator 3 and the magnetic field generating device 4 can be arranged inside the hypersonic aircraft, ensuring that the system has the advantages of being controllable, stable, and not changing the aerodynamic shape of the aircraft.

[0057] Application examples: This example verifies the effectiveness of the proposed drag reduction and heat protection method for hypersonic aircraft. As shown in Table 1, the flight conditions of the RAM-C II hypersonic aircraft are used as the model flow conditions, where the flow consists of two components, nitrogen and oxygen, with a flow velocity of 7650 m / s, a flow pressure of 19.701 Pa, and a flow temperature of 254 K. Figure 2 As shown, the simulation model is the hypersonic vehicle blunt body geometry model 1, which adopts a hemispherical cylinder structure and a two-dimensional axisymmetric simulation. The wall adopts a no-slip isothermal non-catalytic wall, and the wall temperature is 1200K. The distance L between the energy deposition position and the blunt body stagnation point satisfies L / 2R=1, where the hemisphere radius R is 0.1524m. The energy deposition model adopts an instantaneous energy deposition model that satisfies the Gaussian spherical distribution. The control equation is added as an energy source term. The output energy of a single-pulse laser energy deposition is 1.0J, and the energy absorption rate of the air is 0.8, that is, the laser energy deposition area absorbs 800mJ of energy, the laser pulse width is 10ns, and the focal radius is 0.9mm. The magnetic field layout generated by the magnetic field generator is an ideal dipole magnetic field layout, satisfying

[0058] Among them, the magnetic field strength at the stationary point is B 0 is 1.0T, r b is the radius of the hemisphere. B x , B y The magnetic field is x , y The intensity components in two directions. The low magnetic Reynolds number assumption is adopted, and the magnetic fluid flow control is added by adding the Lorentz force source term and the Joule heat source term. In order to better restore the thermochemical non-equilibrium plasma flow field of the hypersonic vehicle, the conductivity model of ionized component migration collision is adopted.

[0059] Table 1 shows the flight parameters of the hypersonic vehicle.

[0060] During the simulation, the model's hypersonic steady-state flow field must first be obtained, and then single-pulse energy deposition is carried out based on the steady-state flow field results. In order to simulate different combinations of energy deposition and magnetofluid flow control, two interaction conditions of energy deposition and magnetofluid flow control are set according to the timing of magnetic field application: one is that magnetofluid flow control and energy deposition are performed simultaneously on the basis of the steady-state flow field, represented by ED and MHD, and the other is that energy deposition is performed based on the steady-state results of magnetofluid flow control, represented by ED after MHD. Figure 3 and Figure 4The results show that compared with the original hypersonic vehicle drag and heat flow environment (the blue line at 0 microseconds), when only energy deposition is performed, the average drag of the vehicle decreases by 3.4%, but its heat flow increases by up to 1.2 times, and the drag has obvious impact behavior. When energy deposition and magnetic fluid flow control are applied simultaneously, compared with the condition of energy deposition alone, the appearance time of the peak and valley values ​​of drag and heat flow is delayed, and the effect of magnetic fluid flow control suppresses the peak values ​​of drag and heat flow to a certain extent, especially the second more prominent peak part. Under this condition, the average aerodynamic drag decreases by 11.9%, and the maximum decrease in heat flow can reach 62.3%. When energy deposition is applied after the magnetohydrodynamic flow control is stabilized, the drag reduction and heat protection effects of this combination are better. Compared with the condition of energy deposition alone, the time lag of the peak and valley values ​​of drag and heat flux is more obvious, and the effect of magnetohydrodynamic flow control on the suppression of drag and heat flux peaks is more significant. Under this condition, the average aerodynamic drag decreases by 18.8%, and the maximum heat flux decreases by 62%. In addition, the total heat flux level under this condition is always lower than the total heat flux of the original hypersonic vehicle.

[0061] Under the same flight conditions, the drag reduction and heat protection method for hypersonic aircraft provided by the present invention is based on the combination of energy deposition and magnetic fluid flow control; it can not only further optimize the effect of reducing the aerodynamic drag of the aircraft achieved by the energy deposition method, but also effectively solve the problem of significant increase in heat flow during some periods of time caused by energy deposition for the aircraft, and at the same time, it can fully suppress the large impact and resistance oscillation caused by energy deposition for the aircraft. Therefore, the combination of the two flow control methods can effectively reduce the drag of the hypersonic aircraft and improve the thermal protection capability of the aircraft, and it has broad application prospects.

[0062] In summary, the present invention provides a drag reduction and heat protection system and method for a hypersonic aircraft, which has the following advantages: As a new concept of active flow control method, the drag reduction and heat protection technology based on the combination of energy deposition and magnetofluid flow control has the advantages of controllability, stability, no change in the aerodynamic shape of the aircraft, and no working fluid consumption. This method is a combination of the energy deposition method in active flow control and the magnetofluid flow control method. On the one hand, the excellent drag reduction characteristics of energy deposition are used to bring good drag reduction effects to the aircraft. At the same time, considering that energy deposition can be used as an auxiliary ionization technology, the magnetic control effect of magnetofluid flow control is improved by improving the fluid conductivity. On the other hand, the outstanding thermal protection performance of magnetofluid flow control is used to bring excellent heat protection effects to the aircraft after dealing with the heat flow growth caused by the energy deposition process in some periods. At the same time, with the help of the Lorentz force of the magnetic field, the resistance impact and oscillation problems caused by pulse energy deposition are fully suppressed. Therefore, the development of this active flow control technology combining energy deposition with magnetofluid flow control is of great significance to the drag reduction and heat protection requirements of hypersonic aircraft.

[0063] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A method for reducing drag and protecting against heat of a hypersonic vehicle, characterized in that: include: Based on the laser excitation method, the laser is emitted and focused in front of the hypersonic vehicle for energy deposition; A magnetic field is generated around a hypersonic vehicle, and a Lorentz force is exerted on the flow field to achieve magnetohydrodynamic flow control of the fluid in the flow field.

2. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 1, characterized in that: in, First, the fluid in the flow field is subjected to magnetofluid flow control by applying Lorentz force; After the hypersonic steady-state flow field is formed, energy deposition is carried out.

3. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 1, characterized in that: in, The magnetic fluid flow control process and the energy deposition process are carried out simultaneously.

4. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 1, characterized in that: The applied Lorentz force satisfies the following conditions: The applied Lorentz force has two components, one component is opposite to the flow direction and is used to reduce the flow velocity; the other component is perpendicular to the flow direction and is used to increase the shock wave separation distance and reduce the shock wave drag.

5. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 1, characterized in that: By adjusting the position of energy deposition and the direction of the magnetic field, the aerodynamic force acting on the hypersonic aircraft can be changed, thereby adjusting the attitude and flight trajectory of the hypersonic aircraft.

6. The method for reducing drag and protecting heat of a hypersonic vehicle according to claim 1, characterized in that: The generated magnetic field adopts a dipole-like magnetic field layout.

7. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 6, characterized in that: The dipole-like magnetic field layout meets the following conditions: In the formula, B The magnetic field is x , y , z A vector consisting of intensity components in three directions; B 0 is the magnetic field strength at the stationary point; r b is the radius of the hemisphere of the hypersonic vehicle.

8. The method for reducing drag and protecting against heat of a hypersonic vehicle according to claim 1, characterized in that: The energy deposition parameters in the energy deposition process are adjusted according to the flight conditions of the hypersonic aircraft; the energy deposition parameters include deposition position, deposition center area size, laser energy and laser pulse width.

9. A drag reduction and heat protection system for a hypersonic aircraft, used to implement the drag reduction and heat protection method for a hypersonic aircraft according to any one of claims 1 to 8, characterized in that: It comprises a pulse laser generator (3) and a magnetic field generating device (4); The pulse laser generator (3) is arranged at the head of the hypersonic aircraft and is used to emit laser light and focus it in front of the hypersonic aircraft, thereby performing energy deposition; The magnetic field generating device (4) is connected to the hypersonic aircraft and is used to generate a magnetic field around the hypersonic aircraft, and to achieve magnetic fluid flow control of the fluid in the flow field by applying a Lorentz force to the flow field.

10. The drag reduction and heat protection system for a hypersonic aircraft according to claim 9, characterized in that: The pulse laser generator (3) and the magnetic field generating device (4) are both arranged inside the hypersonic aircraft.

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