Aerodynamic configuration design method considering reduction of interference of shock waves on canard rudder

Abstract

The invention discloses an aerodynamic configuration design method considering reduction of interference of shock waves on a canard rudder, and the method comprises the steps: firstly, calculating an interference angle and an interference range of an oblique shock wave of a missile body according to a cone angle of the head of the missile body; secondly, according to the position of the canard rudder on the projectile body, the distance between the projectile body and the oblique shock wave at the position is determined, and therefore the extension length of the canard rudder is determined; and finally, determining the radius of the rudder leading edge and the sweepback angle of the rudder leading edge by taking the thermal response temperature of the rudder leading edge as a judgment standard, thereby further reducing the surface temperature of the rudder leading edge and achieving the purpose of reducing the cost of allowable materials of the canard rudder. By means of the aerodynamic configuration design method, the canard rudder can avoid missile body shock wave interference, the radius of the front edge of the canard rudder can be as low as 2 mm, it can be guaranteed that ablation deformation does not occur when the maximum heat flow of the front edge of the canard rudder does not exceed 11 MW / m < 2 >, and compared with a traditional canard rudder, the canard rudder has the advantages that the cost of materials used by the canard rudder is reduced, near-zero ablation is achieved, and the good aerodynamic configuration is maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft, and in particular relates to an aerodynamic configuration design method that takes into account reducing the interference of shock waves on canard rudders. Background Art

[0002] At present, the development trend of various aircraft is longer range, smaller size and lighter weight. In order to facilitate high-maneuverability flight of aircraft and improve control response, canard layout is selected for control. Within the range of flight Mach number and flight angle of attack, canard is generally arranged at the head of the aircraft. The canard will be disturbed by the shock wave generated by the head of the missile body, resulting in the canard facing a complex aerodynamic thermal environment, which increases the local heat flow at the leading edge of the canard by 3 to 5 times. The traditional method is to increase the thickness of the heat protection layer and passively adapt the performance, but it will increase the cost of heat protection and increase the resistance of the whole missile.

[0003] Therefore, researching a low-cost canard rudder suitable for high-speed aircraft is a key issue that needs to be solved urgently. The design process of the canard rudder is usually to ensure that the structural space requirements are met, followed by meeting the basic aerodynamic performance indicators, and the most important thing is to reduce the cost of the thermal protection materials of the rudder surface. The design process usually proposes the initial aerodynamic shape, and then evaluates its aerodynamic thermal environment and structural thermal response temperature. If the canard rudder temperature does not meet the allowable requirements of the structural material, the aerodynamic shape of the canard rudder needs to be improved. After several iterations of the design cycle, the final canard rudder shape is obtained.

[0004] This design method, which is mainly based on aerodynamics and supplemented by aerodynamic heat, is not optimal in terms of design results and design cycle. The main disadvantages are as follows: First, the shape of the canard rudder is mainly based on meeting the requirements of aerodynamic performance indicators. The result of aerodynamic design is often only able to meet the basic aerodynamic performance indicators, and the structural thermal response temperature is not relatively optimal; second, the design cycle is long. Usually, structural designers only design the shape of the canard rudder by meeting the aerodynamic performance indicators, and cannot meet the allowable requirements of the temperature of the used materials. This will lead to a longer design iteration cycle for aerodynamics and aerodynamic heat. Therefore, how to streamline the design process, shorten the design cycle, take into account the aerodynamic heat and aerodynamic performance of the canard rudder, and reduce the thermal protection cost of the canard rudder has become a technical problem that needs to be solved urgently in the aerodynamic design of supersonic canard rudders. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides an aerodynamic configuration design method that takes into account reducing the interference of shock waves on canard rudders. First, based on the cone angle of the projectile head, the interference angle and interference range of the oblique shock wave of the projectile body are calculated; secondly, based on the position of the canard rudder on the projectile body, the distance of the projectile body from the oblique shock wave at this position is determined, thereby determining the length of the canard rudder; finally, the rudder leading edge thermal response temperature is used as a criterion to determine the rudder leading edge radius and the rudder leading edge sweep angle, thereby further reducing the surface temperature of the rudder leading edge and achieving the purpose of reducing the cost of allowable materials for the canard rudder. Through this aerodynamic configuration design method, the canard rudder can avoid the interference of the projectile body shock wave, and the leading edge radius of the canard rudder can be as low as 2mm, which can ensure that the maximum heat flux at the leading edge of the rudder does not exceed 11MW / m 2 No ablation deformation occurs. Compared with the traditional canard rudder, it has the characteristics of reducing the material cost of the canard rudder and near-zero ablation, maintaining a good aerodynamic shape.

[0006] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0007] Step 1: Calculation and analysis of the shock wave interference zone of the missile body;

[0008] Firstly, according to the flight trajectory of the aircraft, a typical trajectory is selected to obtain the trajectory characteristic points with the maximum Mach number and angle of attack; secondly, according to the semi-cone angle of the projectile head, the interference angle and interference range of the oblique shock wave at the projectile head are determined;

[0009] Step 2: Design the span size of the duck rudder;

[0010] According to the overall indicators, the canard rudder index is decomposed and designed. The decomposed indicators are: the minimum static stability of the whole missile, the control efficiency and the maximum overload, and the projection area of ​​the rudder surface is determined; according to the limitation of the interference area of ​​the missile body, the maximum extension length of the rudder surface is determined;

[0011] Step 3: Design the sweep angle and radius of the leading edge of the canard rudder;

[0012] The leading edge of the rudder is made of heat-resistant material, with a design margin reserved. The radius of the rudder leading edge fillet and the leading edge sweep angle are reversely designed based on the thermal response temperature at the stationary point.

[0013] Step 4: Canard rudder plane configuration design and temperature verification;

[0014] According to the design results of the canard span and sweep angle and the flight trajectory conditions, the interference flow field between the projectile body and the canard is checked and calculated so that the canard can avoid the interference area of ​​the oblique shock wave generated by the projectile body. If the design results meet the design requirements, the final canard shape is determined. Otherwise, return to step 2 for iterative design until the canard shape meets the allowable temperature requirements of low-cost materials and the overall index requirements.

[0015] Preferably, the step 1 is specifically:

[0016] The shock wave angle of the oblique shock wave generated by the missile body is calculated according to the blunt leading edge flat plate to calculate the interference area of ​​the canard oblique shock wave. According to the opposite cone flow deflection angle, the expression of the canard oblique shock wave and the cone deflection angle is as follows:

[0017] (1)

[0018] in is the Mach number before the shock wave, is the oblique shock angle, is the flow deflection angle, is the specific heat ratio.

[0019] Preferably, the step 2 is specifically:

[0020] According to the size limitation of the canard rudder, the installation position of the canard rudder on the missile body is determined, and then the distance between the missile body and the oblique shock wave is calculated based on the installation position of the canard rudder on the missile body, so as to determine the maximum span of the canard rudder.

[0021] Preferably, the step 3 is specifically:

[0022] According to the wide speed range and wide airspace flight envelope of the aircraft, the engineering calculation formula of the heat flux density function of the missile body stagnation point is introduced as follows:

[0023] (2)

[0024] in: represents the heat flux density on the leading edge stagnation line; Indicates the stagnation point radius of the rudder surface; represents the incoming atmospheric density, Indicates the incoming flow velocity, represents the wall enthalpy, represents the stagnation point enthalpy, represents the power coefficient, Indicates the effective sweep angle of the rudder front edge;

[0025] The leading edge of the canard rudder is made of metal material. According to the limit temperature of the metal material, the maximum heat flux at the leading edge of the rudder is calculated, so as to optimize and iterate the fillet radius and leading edge sweep angle of the rudder leading edge to meet the allowable requirements.

[0026] Preferably, the step 4 is specifically:

[0027] The area of ​​the canard is determined according to the minimum static stability and control efficiency of the aircraft. The span and leading edge sweep angle of the canard are determined according to the previous two steps. Then the root chord length and tip chord length of the canard are determined, so as to design the aerodynamic shape of the canard. The thickness of the skin on the canard is determined according to the response temperature of the cone surface on the canard. The basic aerodynamic performance of the canard is evaluated. If the design result meets the design requirements, the final canard shape is determined. Otherwise, return to step 2 for iterative design until the canard shape meets both the structural strength requirements and the overall index requirements.

[0028] Preferably, the effective sweep angle of the leading edge satisfies hour, .

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention proposes a method for designing a high-speed canard aerodynamic configuration that avoids interference from the shock wave of the projectile body, designs a canard configuration with excellent aerodynamic performance and low use cost, and the method has broad application prospects.

[0031] (1) The canard rudder avoids the interference of shock waves generated by the missile body, which significantly reduces the heat flux in the interference area at the leading edge of the rudder;

[0032] (2) The rudder leading edge material is made of low-cost heat-resistant material. Through the comprehensive optimization design of the rudder leading edge radius and sweep angle, the rudder leading edge radius can be reduced to 2mm, which can ensure that the maximum heat flux at the rudder leading edge does not exceed 11MW / m 2 No ablation deformation occurs; BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is the work flow chart of the present invention.

[0034] Figure 2 Schematic diagram of the canard flow field structure under the interference of the missile body.

[0035] Description of the accompanying figures: 1. Shock wave generated by the projectile body; 2. Interference area of ​​shock wave on the canard rudder; 3. Sweep angle of the leading edge of the canard rudder. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] The present invention proposes a method for designing a canard rudder aerodynamic configuration that avoids shock wave interference. The method takes the nominal trajectory of the current state as a basis and the thermal response temperature of the leading edge of the canard rudder as a judgment criterion, so that the canard rudder can avoid shock wave interference at the head of the projectile, thereby reducing the temperature at the leading edge of the canard rudder, thereby reducing the cost of using rudder surface materials and achieving the ultimate goal of reducing the cost of the canard rudder.

[0038] The flight speed domain-airspace span range of long-range missiles in the atmosphere is large. In the full flight envelope, the shock wave generated by the head of the projectile will also form shock wave interference on the leading edge of the rudder, causing the heat flow at the leading edge of the rudder to increase exponentially. The traditional method is to increase the thickness of the heat protection layer and replace the structural materials that bear higher temperatures to passively adapt, which will increase the heat protection cost and increase the resistance of the entire projectile. The present invention first determines the spanwise distance of the oblique shock wave from the projectile body at the installation position of the canard rudder by calculating the shock wave interference area in the entire trajectory, and determines the maximum span of the canard rudder; secondly, according to the allowable temperature of the leading edge material of the rudder, the leading edge radius and the leading edge sweep angle of the canard rudder are determined. By reasonably designing the span length and leading edge sweep angle of the canard rudder, the interference of the shock wave of the projectile body is avoided, and the aerodynamic performance of the canard rudder is taken into account, thereby determining the geometric shape of the canard rudder, reducing the use cost of the rudder surface, and realizing the integrated design of the aerodynamic configuration under the aerodynamic thermal constraints of the canard rudder.

[0039] Here are the steps:

[0040] Step 1: Calculation and analysis of the shock wave interference zone of the missile body;

[0041] First, according to the flight trajectory of the aircraft, a typical trajectory is selected to obtain the trajectory feature points with the maximum Mach number and angle of attack. Secondly, according to the semi-cone angle of the projectile head, the interference angle and interference range of the oblique shock wave at the projectile head are determined.

[0042] Step 2: Design the span size of the canard rudder;

[0043] According to the overall indicators, the canard rudder index is decomposed and designed, and the decomposed indicators are: the minimum static stability of the whole missile, the control efficiency and the maximum overload, and the projection area of ​​the rudder surface is determined. The key is to determine the maximum extension of the rudder surface according to the limitation of the interference area of ​​the missile body.

[0044] Step 3: Design the sweep angle and radius of the leading edge of the canard rudder;

[0045] The leading edge of the rudder is made of low-cost heat-proof material with a reserved design margin. The rudder front edge fillet radius and leading edge sweep angle are reversely designed based on the thermal response temperature at the stagnation point.

[0046] Step 4: canard rudder plane configuration design and temperature verification;

[0047] According to the design results of the canard span and sweep angle as well as the flight trajectory conditions, the interference flow field between the missile body and the canard is verified and calculated so that the canard can avoid the interference area of ​​the oblique shock wave generated by the missile body. If the design results meet the design requirements, the final canard shape can be determined. Otherwise, return to step 2 for iterative design until the canard shape meets both the allowable temperature requirements of low-cost materials and the overall index requirements.

[0048] Example:

[0049] According to the determined aerodynamic shape of the aircraft body, ballistic simulation is carried out to obtain the parameters of the trajectory characteristic points, mainly including: Mach number, angle of attack, flight altitude, etc., to complete the interference boundary of the oblique shock wave generated by the body.

[0050] The shock wave angle of the oblique shock wave generated by the missile body is calculated according to the blunt leading edge flat plate. The interference area of ​​the canard oblique shock wave is mainly calculated according to the deflection angle of the opposite cone flow. The expression of the canard oblique shock wave and the cone deflection angle is as follows:

[0051] (1)

[0052] in is the Mach number before the shock wave, is the oblique shock angle, is the flow deflection angle, is the specific heat ratio;

[0053] Secondly, the canard rudder index is decomposed and designed according to the overall index, and the decomposed index is: the minimum static stability of the whole missile, the control efficiency and the maximum overload, and the projected area of ​​the rudder surface is determined. The key is to determine the installation position of the canard rudder on the missile body according to the size limit of the canard rudder, and then calculate the distance between the missile body and the oblique shock wave according to the installation position of the canard rudder on the missile body, so as to determine the maximum span of the canard rudder.

[0054] Then, according to the canard rudder span determined above, the leading edge sweep angle and leading edge radius of the canard rudder are optimized and combined. In order to ensure that the leading edge of the rudder still has sufficient strength and shape-maintaining capacity under high-temperature thermal loads, the material of the leading edge of the rudder is low-cost metal material.

[0055] According to the wide speed range and wide airspace flight envelope of the aircraft, in order to quickly iterate the calculation of the aerodynamic thermal environment of the canard, the engineering calculation formula of the heat flux density function of the missile body stagnation point is introduced, as shown below:

[0056] (2)

[0057] The leading edge of the canard rudder is made of low-cost metal material. According to the limit temperature of the low-cost metal material, the maximum heat flux at the leading edge of the rudder is inversely calculated, so as to optimize and iterate the fillet radius and leading edge sweep angle of the rudder leading edge to meet the allowable requirements.

[0058] The area of ​​the canard is determined according to the minimum static stability and control efficiency of the aircraft, the span and leading edge sweep angle of the canard are determined according to the previous two steps, and then the root chord length and tip chord length of the canard are determined, so as to design the aerodynamic shape of the canard, and the thickness of the skin on the canard is determined according to the response temperature of the cone surface on the canard. And its basic aerodynamic performance is evaluated. If the design results meet the design requirements, the final canard shape can be determined, otherwise return to step 2 for iterative design until the canard shape meets both the structural strength requirements and the overall index requirements.

Claims

1. An aerodynamic configuration design method considering reducing the interference of shock waves on canard rudder, characterized in that: The steps include: Step 1: Calculation and analysis of the shock wave interference zone of the missile body; Firstly, according to the flight trajectory of the aircraft, a typical trajectory is selected to obtain the trajectory characteristic points with the maximum Mach number and angle of attack; secondly, according to the semi-cone angle of the projectile head, the interference angle and interference range of the oblique shock wave at the projectile head are determined; Step 2: Design the span size of the duck rudder; According to the overall indicators, the canard rudder index is decomposed and designed. The decomposed indicators are: the minimum static stability of the whole missile, the control efficiency and the maximum overload, and the projection area of ​​the rudder surface is determined; according to the limitation of the interference area of ​​the missile body, the maximum extension length of the rudder surface is determined; Step 3: Design the sweep angle and radius of the leading edge of the canard rudder; The leading edge of the rudder is made of heat-resistant material, with a design margin reserved. The radius of the rudder leading edge fillet and the leading edge sweep angle are reversely designed based on the thermal response temperature at the stationary point. Step 4: Canard rudder plane configuration design and temperature verification; According to the design results of the canard span and sweep angle and the flight trajectory conditions, the interference flow field between the projectile body and the canard is checked and calculated so that the canard can avoid the interference area of ​​the oblique shock wave generated by the projectile body. If the design results meet the design requirements, the final canard shape is determined. Otherwise, return to step 2 for iterative design until the canard shape meets the allowable temperature requirements of low-cost materials and the overall index requirements.

2. The aerodynamic configuration design method according to claim 1, characterized in that: The step 1 is specifically as follows: The shock wave angle of the oblique shock wave generated by the missile body is calculated according to the blunt leading edge flat plate to calculate the interference area of ​​the canard oblique shock wave. According to the opposite cone flow deflection angle, the expression of the canard oblique shock wave and the cone deflection angle is as follows: （1） in is the Mach number before the shock wave, is the oblique shock angle, is the flow deflection angle, is the specific heat ratio.

3. The aerodynamic configuration design method according to claim 2, characterized in that: The step 2 is specifically as follows: According to the size limitation of the canard rudder, the installation position of the canard rudder on the missile body is determined, and then the distance between the missile body and the oblique shock wave is calculated based on the installation position of the canard rudder on the missile body, so as to determine the maximum span of the canard rudder.

4. The aerodynamic configuration design method according to claim 3, characterized in that: The step 3 is specifically as follows: According to the wide speed range and wide airspace flight envelope of the aircraft, the engineering calculation formula of the heat flux density function of the missile body stagnation point is introduced as follows: （2） in: represents the heat flux density on the leading edge stagnation line; Indicates the stagnation point radius of the rudder surface; represents the incoming atmospheric density, Indicates the incoming flow velocity, represents the wall enthalpy, represents the stagnation point enthalpy, represents the power coefficient, Indicates the effective sweep angle of the rudder front edge; The leading edge of the canard rudder is made of metal material. According to the limit temperature of the metal material, the maximum heat flux at the leading edge of the rudder is calculated, so as to optimize and iterate the fillet radius and leading edge sweep angle of the rudder leading edge to meet the allowable requirements.

5. The aerodynamic configuration design method according to claim 4, characterized in that: The step 4 is specifically as follows: The area of ​​the canard is determined according to the minimum static stability and control efficiency of the aircraft. The span and leading edge sweep angle of the canard are determined according to the previous two steps. Then the root chord length and tip chord length of the canard are determined, so as to design the aerodynamic shape of the canard. The thickness of the skin on the canard is determined according to the response temperature of the cone surface on the canard. The basic aerodynamic performance of the canard is evaluated. If the design result meets the design requirements, the final canard shape is determined. Otherwise, return to step 2 for iterative design until the canard shape meets both the structural strength requirements and the overall index requirements.

6. The aerodynamic configuration design method according to claim 5, characterized in that: The effective sweep angle of the leading edge satisfies hour, .

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