A pneumatic configuration design method considering reducing the interference of shock waves on canards

Abstract

The present invention discloses a pneumatic configuration design method for considering reducing the interference of shock waves on canards. First, according to the cone angle of the warhead of the projectile body, the interference angle and interference range of the oblique shock wave of the projectile body are calculated; secondly, according to the position of the canard on the projectile body, the distance between the projectile body and the oblique shock wave at this position is determined, so as to determine the span length of the canard; finally, taking the thermal response temperature of the leading edge of the rudder as the judgment criterion, the radius of the leading edge of the rudder and the sweep angle of the leading edge of the rudder are determined, so as to further reduce the surface temperature of the leading edge of the rudder, achieving the purpose of reducing the cost of the allowable material of the canard. Through this pneumatic configuration design method, the canard can avoid the interference of the shock wave of the projectile body, and the radius of the leading edge of the canard can be as low as 2 mm, which can ensure that no ablation deformation occurs when the maximum heat flux at the leading edge of the rudder does not exceed 11 MW / m<supgt;2< / supgt>. Compared with the traditional canard, it has the characteristics of reducing the cost of the materials used for the canard and nearly zero ablation, and maintaining a good aerodynamic shape.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft, and particularly relates to an aerodynamic configuration design method considering reducing the interference of shock waves on canards. Background Art

[0002] At present, the development trend of various aircraft is to have a longer range, a smaller volume, and a lighter mass. In order to facilitate the high-maneuver flight of the aircraft and improve the control response, a canard layout is selected for control. Within the range of flight Mach number and flight angle of attack, the canards are generally arranged at the head of the aircraft. The canards will be interfered by the shock waves generated at the head of the fuselage, resulting in a complex aerodynamic heat environment for the canards, increasing the local heat flux at the leading edge of the canards by 3 to 5 times. The traditional method is to passively adapt by increasing the thickness and performance of the thermal protection layer, but this will lead to an increase in the thermal protection cost and at the same time increase the total drag of the whole missile.

[0003] Therefore, researching a low-cost canard applicable to high-speed aircraft is a key problem to be solved urgently. For the design process of the canard, it usually ensures to meet the structural space requirements first, and then meets the basic aerodynamic performance indicators. The most important thing is to reduce the cost of the thermal protection material of the rudder surface. In the design process, usually the aerodynamics proposes the initial aerodynamic shape, and then evaluates its aerodynamic heat environment and structural thermal response temperature. If the temperature of the canard does not meet the allowable requirements of the structural material, it is necessary to improve the aerodynamic shape of the canard. After several iterations of such design, the final canard shape is obtained.

[0004] This design method mainly based on aerodynamic force and supplemented by aerodynamic heat is not optimal in terms of design results and design cycle. The main disadvantages are as follows: First, the canard shape mainly aims to meet the requirements of aerodynamic performance indicators. The result of aerodynamic design often only meets the basic aerodynamic performance indicator requirements, and the structural thermal response temperature is not relatively optimal; Second, the design cycle is relatively long. Usually, the structural designers only design the canard shape by meeting the aerodynamic performance indicators, which cannot meet the allowable requirements of the temperature of the used material, resulting in an extended design iteration cycle of aerodynamic force and aerodynamic heat. Therefore, how to streamline the design process, shorten the design cycle, simultaneously take into account the aerodynamic heat and aerodynamic force performance of the canard, and reduce the thermal protection cost of the canard has become a technical problem urgently to be solved in the aerodynamic design of supersonic canards. Summary of the Invention

[0005] To overcome the deficiencies of the prior art, the present invention provides a pneumatic configuration design method that takes into account reducing the interference of shock waves on canards. First, according to the cone angle of the missile body head, the interference angle and interference range of the oblique shock wave of the missile body are calculated; secondly, according to the position of the canard on the missile body, the distance from the missile body to the oblique shock wave at this position is determined, thereby determining the span of the canard; finally, taking the thermal response temperature of the leading edge of the rudder as the judgment criterion, the radius of the leading edge of the rudder and the sweep angle of the leading edge of the rudder are determined, so as to further reduce the surface temperature of the leading edge of the rudder and achieve the purpose of reducing the cost of the allowable material of the canard. Through this pneumatic configuration design method, the canard can avoid the interference of the missile body shock wave, and the radius of the leading edge of the canard can be as low as 2 mm, which can ensure that the maximum heat flux at the leading edge of the rudder does not exceed 11 MW / m 2 When there is no ablation deformation, compared with the traditional canard, it has the characteristics of reducing the cost of the materials used for the canard and nearly zero ablation, and maintaining a good aerodynamic shape.

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

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

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

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

[0010] According to the overall indicators, the canard indicators are decomposed and designed. The decomposed indicators are: 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; according to the limitation of the missile body interference area, the maximum span of the rudder surface is determined;

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

[0012] The leading edge of the rudder uses heat-resistant materials and reserves a design margin. Based on the thermal response temperature at the stagnation point, the fillet radius of the leading edge of the rudder surface and the sweep angle of the leading edge are designed by inverse design;

[0013] Step 4: Design of the canard plane configuration and temperature check;

[0014] According to the design results of the canard span and sweep angle and the flight ballistic conditions, the interference flow field check calculation of the missile body and the canard is carried out to make the canard 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 is determined; otherwise, return to Step 2 for iterative loop design until the canard shape simultaneously meets the temperature allowable requirements of low-cost materials and the overall indicator requirements.

[0015] Preferably, the specific content of Step 1 is:

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

[0017] (1)

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

[0019] Preferably, the specific content of step 2 is as follows:

[0020] According to the size limit of the canard, determine the installation position of the canard on the body. Then, according to the installation position of the canard on the body, calculate the distance between the body and the oblique shock wave, so as to determine the maximum span of the canard.

[0021] Preferably, the specific content of step 3 is as follows:

[0022] According to the flight envelope of the aircraft in a wide speed range and a wide airspace, introduce the engineering calculation formula of the stagnation point heat flux density function of the body, as shown below:

[0023] (2)

[0024] Where: represents the heat flux density on the leading edge stagnation line; represents the stagnation radius of the leading edge of the rudder surface; represents the density of the oncoming atmosphere, represents the oncoming flow velocity, represents the wall enthalpy value, represents the stagnation enthalpy value, represents the power coefficient, represents the effective sweep angle of the leading edge of the rudder surface;

[0025] The leading edge of the canard is made of metal material. According to the maximum temperature borne by the metal material, the maximum heat flux at the leading edge of the rudder surface is calculated inversely, and then the fillet radius and leading edge sweep angle of the rudder leading edge are optimized and iteratively selected to meet the allowable requirements.

[0026] Preferably, the specific content of step 4 is as follows:

[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 based on 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. According to the response temperature of the upper conical surface of the canard, the thickness of the skin on the canard is determined; and 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 loop 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 When .

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

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

[0031] (1) The canard avoids the interference of the shock wave generated by the body, resulting in a significant reduction in the heat flux in the interference area at the leading edge of the rudder.

[0032] (2) The material of the leading edge of the rudder is selected as a low-cost heat-resistant material. Through the comprehensive optimization design of the radius and sweep angle of the leading edge of the rudder surface, the radius of the leading edge of the rudder can be as low as 2 mm, which can ensure that no ablation deformation occurs when the maximum heat flux at the leading edge of the rudder does not exceed 11 MW / m 2 . Description of the Drawings

[0033] Figure 1 is the workflow diagram of the present invention.

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

[0035] Description of the Drawings: 1. Shock wave generated by the body; 2. Interference area of the shock wave on the canard; 3. Leading-edge sweep angle of the canard. Detailed Embodiments

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

[0037] The present invention proposes a design method for the aerodynamic configuration of a canard that avoids shock wave interference. Based on the nominal trajectory of the current state and taking the thermal response temperature of the leading edge of the canard as the judgment criterion, the canard is made to avoid the interference of the head shock wave of the body, thereby reducing the temperature at the leading edge of the canard, achieving the ultimate goal of reducing the use cost of the rudder surface material and realizing the reduction of the cost of the canard.

[0038] For long-range projectiles flying within the atmosphere, the flight speed and altitude span a large range. Throughout the entire flight envelope, the shock wave generated at the head of the projectile body will also cause shock interference to the leading edge of the rudder, doubling the heat flux at the leading edge of the rudder. The traditional method is to passively adapt by increasing the thickness of the thermal protection layer and replacing the structural material that can withstand higher temperatures, which will lead to an increase in thermal protection costs and at the same time increase the total drag of the projectile. The present invention first calculates the shock interference region throughout the entire ballistic trajectory, determines the spanwise distance of the oblique shock wave from the projectile body at the installation position of the canard rudder, and determines the maximum span length of the canard rudder; secondly, based on the allowable temperature of the leading edge material of the rudder, determines the leading edge radius and leading edge sweep angle of the canard rudder. By reasonably designing the span length and leading edge sweep angle of the canard rudder to avoid the interference of the projectile body shock wave and taking into account the aerodynamic performance of the canard rudder, the geometric shape of the canard rudder is determined, reducing the usage cost of the rudder surface, and thus realizing the integrated design of the aerodynamic configuration under the aerodynamic heat constraint of the canard rudder.

[0039] The steps are as follows:

[0040] Step 1, calculation and analysis of the shock interference region of the projectile body;

[0041] First, according to the flight trajectory of the aircraft, select a typical ballistic trajectory and obtain the ballistic characteristic points with the maximum Mach number and angle of attack. Secondly, based on the half-cone angle of the projectile body head, determine the interference angle and interference range of the oblique shock wave of the projectile body head.

[0042] Step 2, design of the span length dimension of the canard rudder;

[0043] According to the overall indicators, decompose and design the canard rudder indicators. The decomposed indicators are: the minimum static stability of the entire projectile, the control efficiency and the maximum overload, and determine the projected area of the rudder surface. The key is to determine the maximum span length of the rudder surface according to the limitations of the projectile body interference region.

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

[0045] The leading edge of the rudder uses a low-cost thermal protection material, reserves a design margin, and inversely designs the fillet radius and leading edge sweep angle of the rudder surface according to the thermal response temperature at the stagnation point.

[0046] Step 4, design of the planar configuration of the canard rudder and temperature check;

[0047] According to the design results of the span length and sweep angle of the canard rudder and the flight ballistic conditions, carry out the check calculation of the interference flow field between the projectile body and the canard rudder, so that the canard rudder avoids the interference region of the oblique shock wave generated by the projectile body. If the design results meet the design requirements, the final canard rudder shape can be determined; otherwise, return to Step 2 for iterative loop design until the canard rudder shape simultaneously meets the temperature allowable requirements of the low-cost material and the overall indicator requirements.

[0048] Example:

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

[0050] The shock wave angle of the oblique shock wave generated by the airframe is calculated according to the blunt leading edge flat plate to calculate the interference area of the canard oblique shock wave. It is mainly calculated according to the flow deflection angle of the opposite one-cone. The expressions of the canard oblique shock wave and the one-cone deflection angle are as follows:

[0051] (1)

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

[0053] Secondly, according to the overall indicators, the canard indicators are decomposed and designed. The decomposed indicators are: 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 on the airframe according to the canard size limit, and then calculate the distance between the airframe and the oblique shock wave at the installation position of the canard on the airframe, so as to determine the maximum span of the canard.

[0054] Then, according to the canard span determined above, the leading edge sweep angle and leading edge radius of the canard are optimized and combined. To ensure that the leading edge of the rudder still has sufficient strength and shaping ability under the action of high-temperature thermal load, the material of the leading edge of the rudder is made of low-cost metal material.

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

[0056] (2)

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

[0058] According to the minimum static stability of the aircraft, control efficiency, etc., the area of the canard is determined. According to the canard span and leading edge sweep angle determined in the previous two steps, the root chord length and tip chord length of the canard are determined, so as to design the aerodynamic shape of the canard. According to the response temperature of the upper one-cone surface of the canard, the skin thickness of the canard is determined. And its basic aerodynamic performance is evaluated. If the design result meets the design requirements, the final canard shape can be determined. Otherwise, return to step two for iterative loop 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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