A drag-reducing and heat-protecting system and method for a hypersonic vehicle

Abstract

The application belongs to the field of hypersonic active flow control, and discloses a drag reduction and heat protection system and method for a hypersonic aircraft. The method combines energy deposition and magnetic fluid flow control. Energy deposition has excellent drag reduction characteristics, which can bring good drag reduction effect to the aircraft. Meanwhile, energy deposition can be used as auxiliary ionization technology to improve the magnetic control effect of magnetic fluid flow control by improving the electrical conductivity of the fluid. Magnetic fluid flow control has outstanding heat protection performance, which can bring excellent heat protection effect to the aircraft after dealing with the heat flow growth caused by energy deposition. Meanwhile, the Lorentz force of the magnetic field fully suppresses the resistance impact and shock caused by pulse energy deposition. The method can achieve better hypersonic drag reduction and heat protection effect, effectively reduce the resistance of the hypersonic aircraft and improve the heat protection ability of the aircraft, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hypersonic active flow control technology, specifically relating to a drag reduction and heat protection system and method for hypersonic aircraft. Background Technology

[0002] Hypersonic vehicles face two major challenges when flying at extreme speeds: immense drag and intense aerodynamic heating. The enormous shock wave drag significantly increases the vehicle's energy consumption, thus affecting its flight time and range; intense aerodynamic heating causes a rapid increase in surface temperature, leading to material softening and ablation. These two problems not only limit the vehicle's flight performance but also pose a serious threat to its structural integrity and flight stability. Therefore, designing and developing 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. Passive flow control requires no external energy input and relies on fixed geometry or material properties to influence the flow. Its structure is relatively simple and reliable, but its control effect may fail when flight conditions deviate from the design conditions. Active flow control directly applies appropriate disturbance modes to the flow field and couples them with the flow's inherent patterns to achieve flow control. It can be adjusted in real time according to flight conditions, offering high flexibility and wide applicability. For hypersonic cruise vehicles, whose drag and aerodynamic thermal environment are characterized by high magnitude, long duration, and complex and variable nature, passive flow control methods are insufficient to meet their drag reduction and heat protection requirements. Therefore, active flow control methods are the preferred choice for drag reduction and heat protection design of hypersonic vehicles.

[0004] Currently, active flow control methods typically employ energy deposition, which can achieve excellent drag reduction. However, energy deposition introduces high energy into the flow field, leading to heat flux growth in the aircraft during certain periods. Furthermore, the mainstream energy deposition method using pulse excitation still suffers from significant impact and drag oscillations during drag reduction.

[0005] It is evident that adopting existing drag reduction and heat protection measures for hypersonic vehicles can easily lead to increased heat flux and generate large impacts and drag oscillations, affecting the stability of the vehicle. Summary of the Invention

[0006] This invention provides a drag reduction and heat protection system and method for hypersonic vehicles to solve the technical problem that existing drag reduction and heat protection measures for hypersonic vehicles can easily lead to increased heat flow and large impact and drag oscillation phenomena.

[0007] To achieve the above objectives, the present invention employs the following technical content:

[0008] In a first aspect, the present invention provides a drag reduction and heat protection method for a hypersonic vehicle, comprising:

[0009] Based on laser excitation, a laser is emitted and focused in front of the hypersonic vehicle for energy deposition.

[0010] A magnetic field is generated around the hypersonic vehicle, and the magnetohydrodynamic flow of the fluid in the flow field is controlled by applying Lorentz force to the flow field.

[0011] Furthermore,

[0012] First, the flow of the fluid in the flow field is controlled by applying the Lorentz force.

[0013] After a hypersonic steady-state flow field is formed, energy deposition is then carried out.

[0014] Furthermore,

[0015] In this process, the magnetohydrodynamic flow control process and the energy deposition process occur simultaneously.

[0016] Furthermore,

[0017] The applied Lorentz force satisfies the following condition:

[0018] 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 detachment distance and reduce the shock wave drag.

[0019] Furthermore, by adjusting the location of energy deposition and the direction of the magnetic field to change the aerodynamic forces acting on the hypersonic vehicle, the attitude and flight trajectory of the hypersonic vehicle can be adjusted.

[0020] Furthermore, the generated magnetic field adopts a dipole-like magnetic field layout.

[0021] Furthermore,

[0022] The dipole-like magnetic field layout satisfies the following conditions:

[0023]

[0024] In the formula, B For the magnetic field in x , y , z A vector formed by intensity components in three directions; B 0 represents the magnetic field strength at the stagnation point; r b Let be the radius of the hypersonic vehicle's hemisphere.

[0025] Furthermore,

[0026] The energy deposition parameters during the energy deposition process are adjusted according to the flight conditions of the hypersonic vehicle; the energy deposition parameters include deposition location, size of the deposition center region, laser energy, and laser pulse width.

[0027] In a second aspect, the present invention provides a drag reduction and heat protection system for a hypersonic vehicle, used to implement the above-mentioned drag reduction and heat protection method for a hypersonic vehicle, comprising a pulsed laser generator and a magnetic field generating device;

[0028] The pulsed laser generator is located at the head of the hypersonic vehicle and is used to emit lasers and focus them in front of the hypersonic vehicle to perform energy deposition.

[0029] The magnetic field generator is connected to the hypersonic vehicle and is used to generate a magnetic field around the hypersonic vehicle. By applying Lorentz force to the flow field, the magnetohydrodynamic flow control of the fluid in the flow field can be achieved.

[0030] Furthermore, both the pulsed laser generator and the magnetic field generating device are located inside the hypersonic vehicle.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] This invention provides a drag reduction and heat protection method for hypersonic vehicles. This method combines two active flow control methods: energy deposition and magnetohydrodynamic (MHD) flow control. Energy deposition's excellent drag reduction characteristics provide a significant drag reduction effect for the vehicle. Simultaneously, energy deposition can serve as an auxiliary ionization technique, enhancing the magnetic control effect of MHD flow control by increasing fluid conductivity. MHD flow control's outstanding thermal protection performance, after addressing the heat flux increase during certain periods caused by energy deposition, provides excellent heat protection for the vehicle. Furthermore, the Lorentz force of the magnetic field effectively suppresses the drag impact and oscillation problems caused by pulsed energy deposition. This method achieves superior drag reduction and heat protection for hypersonic vehicles, effectively reducing drag and improving thermal protection capabilities, and has broad application prospects.

[0033] Preferably, in this invention, magnetohydrodynamic flow control is first performed using Lorentz force to form a stable flow field before energy deposition is carried out. This sequential control method makes the effect of magnetohydrodynamic flow control on the suppression of drag and heat flux peaks more significant, further improving drag reduction and heat protection effects.

[0034] Preferably, in this invention, the magnetohydrodynamic flow control and the energy deposition process are carried out simultaneously, which can achieve dynamic regulation of the flow field; thus, it can more flexibly cope with various complex situations that may occur during flight; and the effect of magnetohydrodynamic flow control suppresses the peak values ​​of drag and heat flow to a certain extent, ensuring drag reduction and heat protection effects.

[0035] Preferably, in this invention, by precisely controlling the direction and magnitude of the applied Lorentz force, the velocity and direction of the fluid in the flow field can be precisely controlled; this control method not only helps to reduce the drag and thermal 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 maneuverability of the aircraft.

[0036] Preferably, in this invention, the aerodynamic forces acting on the hypersonic vehicle are 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 vehicle; that is, by adjusting the output energy of the energy deposition laser and the intensity of the applied magnetic field, and controlling the timing of the combination of the two methods, the optimal drag and heat flow reduction of the hypersonic vehicle can be achieved.

[0037] Preferably, in this invention, the use of a dipole-like magnetic field layout can generate 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 magnetohydrodynamic flow control, but also helps to reduce energy consumption and cost.

[0038] Preferably, in this invention, adjusting the energy deposition parameters according to the flight conditions can ensure that the best drag reduction and heat protection effect can be obtained in different flight stages; this dynamic control method not only improves the adaptability and flexibility of the aircraft, but also helps to reduce energy consumption and cost; at the same time, it also helps to improve the reliability and safety of the aircraft.

[0039] This invention also provides a drag reduction and heat protection system for hypersonic vehicles, used to implement the aforementioned drag reduction and heat protection method for hypersonic vehicles. This system includes a pulsed laser generator and a magnetic field generator. The pulsed laser generator emits a laser and focuses it in front of the hypersonic vehicle, thereby depositing energy. A high-energy plasma is formed in the deposition area. The shock wave generated by the expansion of the plasma region interacts with the bow-shaped shock wave at the vehicle's nose, improving the flow field structure and shock wave structure in front of the vehicle, thus achieving excellent drag reduction. The magnetic field generator generates a magnetic field around the hypersonic vehicle. The interaction between the conductive fluid flowing in the magnetic field and the magnetic field enables control of the fluid flow and achieves excellent heat protection. The combination of these two systems enhances the magnetic control effect of the magnetohydrodynamic flow by increasing the fluid conductivity. The Lorentz force of the magnetic field effectively suppresses the drag impact and oscillation problems caused by pulsed energy deposition. By leveraging their respective advantages and compensating for their shortcomings, this system achieves better drag reduction and heat protection for hypersonic vehicles.

[0040] Prior to this invention, both the pulsed laser generator and the magnetic field generator are arranged inside the aircraft, giving the system advantages such as controllability, stability, and no change to the aerodynamic shape of the aircraft. Attached Figure Description

[0041] Figure 1 A logic diagram illustrating a drag reduction and heat protection method for a hypersonic vehicle provided in an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of a drag reduction and heat protection system for a hypersonic vehicle provided in an embodiment of the present invention;

[0043] Figure 3 This is a comparative schematic diagram of the distribution of normalized aerodynamic drag of a blunt body over time under three operating conditions provided in the embodiments of the present invention.

[0044] Figure 4 This is a comparative schematic diagram showing the distribution of total heat flux over time on the bluff body wall under three operating conditions provided in this embodiment of the invention.

[0045] Figure label:

[0046] 1. Blunt body geometric model of hypersonic vehicle; 2. Magnetic field generator; 3. Pulsed laser generator; 4. Energy deposition center. Detailed Implementation

[0047] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0051] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0053] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0054] As mentioned in the background section, current active flow control methods typically employ energy deposition, which can achieve excellent drag reduction. However, because energy deposition introduces high energy into the flow field, it can lead to heat flux growth in the aircraft during certain periods. Furthermore, the mainstream energy deposition method using pulse excitation still suffers from significant impact issues and drag oscillations during the drag reduction process.

[0055] Furthermore, while magnetohydrodynamic flow control can increase the shock wave detachment distance and reduce shock wave drag, when this method is used for drag reduction and heat protection, the reaction force of the Lorentz force will cause a certain increase in the total drag of the aircraft when the magnetic field strength is large.

[0056] To address the aforementioned issues, this embodiment provides a drag reduction and heat protection method for hypersonic vehicles. This method can solve the problems of enormous aerodynamic drag and severe aerodynamic heating faced by hypersonic vehicles.

[0057] To facilitate a better understanding of this technical solution, the following technical terms are explained:

[0058] ED (Energy Deposition): Energy deposition;

[0059] MHD (Magneto Hydrodynamics): Magnetohydrodynamics;

[0060] ED without MHD – Energy deposition only; ED and MHD – Energy deposition and magnetohydrodynamic control are applied simultaneously; ED after MHD – Energy deposition is applied after magnetohydrodynamic control has stabilized.

[0061] like Figure 1 As shown, this embodiment provides a drag reduction and heat protection method for hypersonic vehicles, including the following steps:

[0062] Based on laser excitation, a laser is emitted and focused in front of the hypersonic vehicle for energy deposition.

[0063] A magnetic field is generated around the hypersonic vehicle, and the magnetohydrodynamic flow of the fluid in the flow field is controlled by applying Lorentz force to the flow field.

[0064] In a preferred embodiment, magnetohydrodynamic flow control can be first applied to the fluid in the flow field by applying Lorentz force; after a hypersonic steady-state flow field is formed, energy deposition is then performed. This sequential control method, where magnetohydrodynamic flow control is applied first to control the flow and form a stable flow field before energy deposition, makes the suppression of drag and heat flux peaks more significant, further improving drag reduction and heat protection effects.

[0065] As a preferred embodiment, magnetohydrodynamic flow control and energy deposition processes can be carried out simultaneously, enabling dynamic control of the flow field. This allows for more flexible responses to various complex situations that may occur during flight. Furthermore, the magnetohydrodynamic flow control suppresses the peak values ​​of drag and heat flux to a certain extent, ensuring drag reduction and heat protection effects.

[0066] In this embodiment, the problem of heat flux growth during certain periods in the drag reduction process of energy deposition is effectively solved, while suppressing drag oscillations and impact behaviors caused by pulsed energy deposition. When an aircraft cruises at hypersonic speeds, it faces enormous shock wave drag and severe aerodynamic heating. To address this, a high-energy laser is first focused at a certain position in front of the aircraft using a pulsed laser generator. The shock wave induced by energy deposition interacts with the bow-shaped shock wave at the aircraft's nose, improving the flow field and shock wave structure in front of the aircraft and thus achieving excellent drag reduction. Simultaneously, considering the thermochemical non-equilibrium effect of hypersonic flow and the fact that energy deposition, as an auxiliary ionization method, can improve fluid conductivity, a magnetic field generator inside the aircraft is activated at an appropriate time during the energy deposition process. The interaction between the conductive fluid flowing in the magnetic field and the magnetic field allows for effective control of fluid flow and achieves excellent heat protection, while suppressing drag oscillations and impact behaviors caused by pulsed energy deposition. This invention allows for flexible adjustment of the energy deposition laser output energy and the applied magnetic field strength according to flight conditions, controlling the timing of the combination of the two methods to achieve optimal drag and heat flux reduction for the aircraft under different operating conditions. By changing the location of energy deposition and the direction of the magnetic field generator, the aerodynamic forces acting on the aircraft can be altered, thereby effectively adjusting the aircraft's attitude and flight trajectory. Furthermore, since both the pulsed laser generator 3 and the magnetic field generator 2 can be placed inside the hypersonic vehicle, this method offers advantages such as controllability, stability, and preservation of the hypersonic vehicle's aerodynamic shape.

[0067] Combination Figure 2 As shown, energy deposition is performed using pulsed laser excitation. Appropriate energy deposition parameters are selected based on the hypersonic vehicle's flight conditions, including deposition location, size of the deposition center region, laser energy, and laser pulse width. A pulsed laser generator 3 installed on the head of the hypersonic vehicle emits a laser and focuses it at a position in front of the vehicle 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 region interacts with the bow-shaped shock wave at the head of the vehicle, improving the flow field structure and shock wave structure in front of the vehicle, thereby achieving excellent drag reduction.

[0068] In this embodiment, magnetohydrodynamic (MHD) flow control utilizes a magnetic field generator 2 installed inside the aircraft. The generated magnetic field is arranged as a dipole-like magnetic field. By leveraging the interaction between the conductive fluid flowing in the magnetic field and the magnetic field, the flow of fluid in the flow field is controlled, achieving excellent heat protection. The Lorentz force distribution applied to the flow field by MHD 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 alleviates aerodynamic heating caused by air compression and viscosity. The other component is perpendicular to the flow direction, which increases the shock wave separation distance and reduces shock wave drag. At the same time, the thermal environment on the aircraft surface is improved due to the distance of the high-temperature shock wave layer.

[0069] The combination of energy deposition and magnetohydrodynamic (MHD) control was modified based on the flight conditions of the hypersonic vehicle. By optimizing the proportion of the two methods—adjusting the output energy of the energy deposition laser and the applied magnetic field strength, and controlling the timing of their combination—based on drag characteristics and heat flux distribution features, optimal drag and heat flux reduction for the hypersonic vehicle were achieved.

[0070] 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:

[0071]

[0072] In the formula, x 0, y 0, z 0 indicates the location of the energy deposition center; R x , R y , R z The radius of the depositional region in three directions; ρ The flow field density; g ( t ) is a step function that represents the on and off states of a laser pulse;

[0073]

[0074] In the formula, τ The pulse width of the laser; characteristic parameters of energy deposition. q 0 satisfies

[0075]

[0076] In the formula, Q L Laser output energy is the laser energy deposited by laser energy. η The efficiency of the deposited energy being absorbed by the air;V 0 represents the volume of the laser energy deposition region.

[0077] In this embodiment, the magnetic field generating device is essentially a set of energized coils. By controlling the magnitude of the current flowing through the coils, dipole-like magnetic fields of different magnetic field strengths are generated. The arrangement of the dipole-like magnetic fields satisfies the following conditions:

[0078]

[0079] In the formula, B For the magnetic field in x , y , z A vector formed by intensity components in three directions; B 0 represents the magnetic field strength at the stagnation point; r b Let be the radius of the hypersonic vehicle's hemisphere.

[0080] Furthermore, in this embodiment, the two-dimensional form of the dipole-like magnetic field layout satisfies the following conditions:

[0081]

[0082] In the formula, B 0 represents the magnetic field strength at the stagnation point, a value controlled by the magnitude of the current flowing through the magnetic field generator 2. B A zero value characterizes the difference in the strength of the magnetic field applied by the device; B x , B y The magnetic field is respectively in x , y Intensity components in two directions; r b Let be the radius of the hypersonic vehicle's hemisphere.

[0083] This embodiment also provides a drag reduction and heat protection system for a hypersonic vehicle, which can realize the above-mentioned drag reduction and heat protection method for hypersonic vehicles. It includes a pulsed laser generator 3 and a magnetic field generator 4. The pulsed laser generator 3 is disposed at the head of the hypersonic vehicle and is used to emit lasers and focus them in front of the hypersonic vehicle to perform energy deposition. The magnetic field generator 4 is connected to the hypersonic vehicle and is used to generate a magnetic field around the hypersonic vehicle. By applying Lorentz force to the flow field, the magnetohydrodynamic flow control of the fluid in the flow field is achieved.

[0084] In this embodiment, both the pulsed laser generator 3 and the magnetic field generator 4 can be installed inside the hypersonic vehicle, ensuring that the system has advantages such as controllability, stability, and no change to the aerodynamic shape of the vehicle.

[0085] Application examples:

[0086] This example verifies the effectiveness of the proposed drag reduction and heat protection method for hypersonic vehicles. As shown in Table 1, the flight conditions of the RAM-C II hypersonic vehicle are used as the model's inflow conditions. The inflow consists of nitrogen and oxygen, with an inflow velocity of 7650 m / s, an inflow pressure of 19.701 Pa, and an inflow temperature of 254 K. Figure 2 As shown, the simulation model is a blunt-body geometric model 1 of a hypersonic vehicle, employing a hemispherical cylindrical structure and a two-dimensional axisymmetric simulation. The wall surface is a non-slip, isothermal, and catalytic-free surface with a wall temperature of 1200K. The distance L from the energy deposition location to the stagnation point of the blunt body satisfies L / 2R=1, where the hemispherical radius R is 0.1524m. The energy deposition model adopts an instantaneous energy deposition model satisfying a Gaussian spherical distribution, with the governing equations incorporated as energy source terms. The single-pulse laser energy deposition output energy is 1.0J, the energy absorption rate of air is 0.8, meaning the laser energy deposition region absorbs 800mJ of energy. The laser pulse width is 10ns, and the focal radius is 0.9mm. The magnetic field generated by the magnetic field generator is an ideal dipole magnetic field layout, satisfying...

[0087]

[0088] Among them, the magnetic field strength at the stationary point B 0 represents 1.0T. r b Let be the radius of the hemisphere. B x , B y For the magnetic field in x , y Intensity components in two directions. A low magnetic Reynolds number assumption is adopted, and magnetohydrodynamic flow control is incorporated by adding Lorentz force source terms and Joule heat source terms. To better represent the thermochemical nonequilibrium plasma flow field of a hypersonic vehicle, a conductivity model of ionized component migration and collision is used.

[0089] Table 1 shows the flight parameters of the hypersonic vehicle.

[0090]

[0091] During the simulation, the hypersonic steady-state flow field of the model must first be obtained, and then single-pulse energy deposition is carried out based on the results of this steady-state flow field. To simulate different combinations of energy deposition and magnetohydrodynamic (MHD) control, two interaction conditions between energy deposition and MHD control are set according to the timing of magnetic field application: one is where MHD control and energy deposition are performed simultaneously on the steady-state flow field, denoted as ED and MHD; the other is where energy deposition is performed on the steady-state results of MHD control, denoted as ED after MHD. Figure 3 and Figure 4 The results show that, compared with the original hypersonic vehicle drag and heat flux environment (blue line at 0 microsecond), when only energy deposition was performed, the average drag of the vehicle decreased by 3.4%, but its heat flux increased by up to 1.2 times, and the drag exhibited obvious impact behavior. When energy deposition and magnetohydrodynamic (MHD) control were applied simultaneously, compared with the energy deposition-only condition, the occurrence time of drag and heat flux peaks and troughs was delayed, and the MHD control suppressed the peak values ​​of drag and heat flux to some extent, especially the second prominent peak. Under this condition, the average aerodynamic drag decreased by 11.9%, and the maximum decrease in heat flux reached 62.3%. When energy deposition is applied after the magnetohydrodynamic flow control has stabilized, the drag reduction and heat protection effects under this combination are better. Compared with the energy deposition condition alone, the time lag of the appearance of drag and heat flux peaks and valleys is more obvious. 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 is reduced by 18.8%, the maximum heat flux is reduced by 62%, and the total heat flux level under this condition is always lower than the total heat flux of the original hypersonic vehicle.

[0092] Under the same flight conditions, the drag reduction and heat protection method for hypersonic vehicles provided by this invention is based on a combination of energy deposition and magnetohydrodynamic flow control. This not only further optimizes the aerodynamic drag reduction effect achieved by the energy deposition method, but also effectively solves the problem of significant heat flux increase during certain periods caused by energy deposition, while simultaneously suppressing the large impacts and drag oscillations caused by energy deposition. Therefore, the combination of these two flow control methods can effectively reduce the drag experienced by hypersonic vehicles and improve their thermal protection capabilities, showing broad application prospects.

[0093] In summary, the present invention provides a drag reduction and heat protection system and method for hypersonic vehicles, which has the following advantages:

[0094] The drag reduction and thermal protection technology based on the combination of energy deposition and magnetohydrodynamic (MHD) flow control is a novel active flow control method with advantages such as controllability, stability, no alteration to the aerodynamic shape of the aircraft, and no propellant consumption. This method combines energy deposition and MHD flow control in active flow control. On one hand, the excellent drag reduction characteristics of energy deposition bring good drag reduction to the aircraft. Simultaneously, considering that energy deposition can be used as an auxiliary ionization technique, the magnetic control effect of MHD flow control is improved by increasing the fluid conductivity. On the other hand, the outstanding thermal protection performance of MHD flow control provides excellent thermal protection for the aircraft after handling the heat flux increase during the energy deposition process. Furthermore, the Lorentz force of the magnetic field effectively suppresses the drag impact and oscillation problems caused by pulsed energy deposition. Therefore, developing this active flow control technology combining energy deposition and MHD flow control is of great significance for meeting the drag reduction and thermal protection requirements of hypersonic aircraft.

[0095] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for reducing drag and preventing heat in a hypersonic vehicle, characterized in that, include: Based on laser excitation, a laser is emitted and focused in front of the hypersonic vehicle for energy deposition. A magnetic field is generated around the hypersonic vehicle, and the magnetohydrodynamic flow of the fluid in the flow field is controlled by applying Lorentz force to the flow field. First, the flow of the fluid in the flow field is controlled by applying the Lorentz force. After a hypersonic steady-state flow field is formed, energy deposition is then carried out. In this process, the magnetohydrodynamic flow control process and the energy deposition process occur simultaneously; The applied Lorentz force satisfies the following condition: 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 detachment distance and reduce the shock wave drag.

2. The drag reduction and heat protection method for hypersonic vehicles according to claim 1, characterized in that, By adjusting the location of energy deposition and the direction of the magnetic field, the aerodynamic forces acting on the hypersonic vehicle can be altered, thereby regulating the attitude and flight trajectory of the hypersonic vehicle.

3. The drag reduction and heat protection method for hypersonic vehicles according to claim 1, characterized in that, The generated magnetic field adopts a dipole-like magnetic field layout.

4. The drag reduction and heat protection method for hypersonic vehicles according to claim 3, characterized in that, The dipole-like magnetic field layout satisfies the following conditions: In the formula, B For the magnetic field in x , y , z A vector formed by intensity components in three directions; B 0 represents the magnetic field strength at the stagnation point; r b Let be the radius of the hypersonic vehicle's hemisphere.

5. The drag reduction and heat protection method for hypersonic vehicles according to claim 1, characterized in that, The energy deposition parameters during the energy deposition process are adjusted according to the flight conditions of the hypersonic vehicle; the energy deposition parameters include deposition location, size of the deposition center region, laser energy, and laser pulse width.

6. A drag reduction and heat protection system for a hypersonic vehicle, used to implement the drag reduction and heat protection method for any of claims 1-5, characterized in that, Includes a pulsed laser generator (3) and a magnetic field generating device (4); The pulsed laser generator (3) is located at the head of the hypersonic vehicle and is used to emit lasers and focus them in front of the hypersonic vehicle to perform energy deposition. The magnetic field generating device (4) is connected to the hypersonic vehicle and is used to generate a magnetic field around the hypersonic vehicle. By applying Lorentz force to the flow field, the magnetohydrodynamic flow control of the fluid in the flow field can be achieved.

7. The drag reduction and heat protection system for hypersonic vehicles according to claim 6, characterized in that, Both the pulsed laser generator (3) and the magnetic field generator (4) are located inside the hypersonic vehicle.

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