The sea-effect missile refers to a kind of 6-ship missile that can cruise in the sea surface effect area for a long time. It has strong penetration capability and attacking power, and has a large lift-to-resistance ratio of 6 lines in free space. A new concept missile with a promising future. The aerodynamic characteristics of the missile flying in the sea surface area are different from space and fire. The first is that the lift with the height of the flight 1 is strongly due to the disturbance of the sea surface wind and waves, and the aerodynamic force has an unsteady effect. These features make the shape design of the sea-effect missile and the aerodynamic cloth have different flying missiles. Before entering the sea and in the ground-effect area, the sea-effect missile must first be 6 or more in space, or the actual use of environmental conditions should be changed. The missile should be modified to cruise outside the ground effect area. The shape design and layout should also be considered. To 0 by space.
Despite the established experience of the aerodynamic design of ground-effect aircraft, the sea-effect missile cannot be fully borrowed. Based on the analysis of the aerodynamic characteristics of the ground effect area, this paper proposes a method of aerodynamic design of the sea effect missile. Of course, the shape design of the sea-effect missile must be determined through various simulation tests.
2 Flow characteristics in the ground effect area 2.1 Ground effect and increase mechanism When the 6-way device is close to the ground, the ground is close to the underside of the wing, forcing the air below the ground to flow only through the ground and cannot penetrate the ground, causing the lift of the wing. When increased, the induced resistance decreases and the pressure center moves back. Ground free space for the aircraft.
Ground effect is also called surface effect, slab effect, floor mat effect. Although this effect was solved by people in the 1920s, the airflow flowed through the mountain angle of attack within the ground effect, and the presence of the surface with the flashing ground was squeezed to form the mantle 8. Still, the heart, face music increase people, and 1. The face is basically unaffected, so in the same angle of attack, the lift of the airfoil of the ground effect area will be outside the area of ​​the effect area, and the space will be lifted. At the small angle of attack, this increase effect begins with the decrease of the height of the 6 lines. After the gas drops to a certain critical height, the idle mat is destroyed, and the lift is reduced. When the angle of attack increases, i will mention The emergence of the government, even into the ground effect area, the lift will decrease with the decrease of H. This is because the airflow of the F-wing is blocked, and the floor mat expands forward and escapes. At the negative angle of attack, the Venturi effect occurs, so that the negative pressure of the F-wing increases with the decrease of H, causing the lift to decrease with the decrease of H. It is known that the increase effect mainly depends on the shape under the airfoil, and the shape of the surface is not related. 122.2 The change of the pressure center in the pressure-effect zone inside and outside the ground effect has a significant significance for the analysis of the operational stability of the missile and the aerodynamic layout. Both theoretical and experimental studies have shown that in the effective area, the lift acting on the airfoil can be divided into two parts, independent of the row height, acting near the supersonic speed of the 14-string subsonic horse 2 string; 5; It is the lift caused by the floor mat, which is basically evenly distributed along the string, and the pressure center is between 40. and 50 strings long. Therefore, the total claw center of the airfoil in the ground effect area is shifted back from the space, and the amount of backward movement increases with the angle of attack or the height decreases at a small angle of attack, but the suction force at the high angle of attack is due to the leading edge. More intense than free space, the total pressure center has to move forward, even before the free space pressure.
2.3 Nonlinear unsteady characteristics In the effective area, the variation of the aerodynamic lift pressure pitching moment resistance with the angle of attack and the row height may be nonlinear and non-monotonic, depending on the plane and cross-sectional shape of the airfoil, and the wing tail Layout form. The nonlinear characteristics of the corpse large aspect ratio and the small aspect ratio wing include a small 6 high and a large angle of attack in a fairly wide range of 6 heights and angles of attack. The theoretical calculations agree well with the experimental results. For a large aspect ratio of 5 wings, the linear relationship of aerodynamic force with the angle of attack will decrease with the decrease of day; at the same height, the linear range will decrease with the decrease. The nonlinear characteristics of the medium aspect ratio are more difficult to calculate.
Install the end plate or end body at the wing tip to reduce the drag, increase the lift, and reduce the nonlinear effect of the small and medium aspect ratio wings. From the point of view of the line control, it is always desirable to have a linear relationship with the aerodynamic characteristics as a function of the 6-line parameters.
Due to the movement of the waves and the disturbance of the sea surface, the aerodynamic forces in the sea surface area are always unsteady, especially in the high seas. An important characteristic of unsteady aerodynamics is the time lag effect, which results in the unsynchronization of the height of 6 rows and the height of the waves, that is, the peak of the wave is not the highest point of the 6-row trajectory, resulting in the 6-row device hitting the water during the 6-row process. Danger.
The solution of the nonlinear 1 constant aerodynamic force is much more difficult than the aerodynamic force. In the strict sense, it must be coupled with the flight dynamics calculation. 1 2.4 The wing effect In the sea surface effect area, if the airfoil can be in the jet of the engine and obtain the extra energy of the high-speed jet, the airfoil wing effect depends on the jet velocity, and the airfoil shape is especially the trailing edge. Part and angle of attack If you can add end plates to both ends of the wing, the effect of the wing is better.
3 component shape design 3.1 airfoil design airfoil is the main part of the floor mat lift. In the ground effect area, the aerodynamic characteristics of the airfoil mainly depend on the shape of the cross section. The principle of section design is that within the design height and angle of attack, the flow in the ground effect zone is not damaged, and the total lift energy increases with the increase or decrease of the angle of attack. At the same time, it is necessary to take into account the flow characteristics in space. The Clarke airfoil is chosen for the airfoil of the ground effect machine. The sea effect missile can be selected with a rounded head with a curvature. If you want to obtain the wing effect, the trailing edge of the wing should be equipped with a flap. When cruising, the trailing edge of the flap should be adjusted to a suitable position to make a match. The effect is good.
The most important aspect of the plane parameters is the aspect ratio. From the point of view of increasing the ground effect, the aspect ratio is better. However, when the sea-effect missile enters the sea surface effect area, the wing will be subjected to a large periodic unsteady load, and may also be accompanied by a fixed wave impact. The wing must be set to be a tip-shaped person's trapezoidal wing. And the aspect ratio and wingspan can't be too big. Considering the launch condition, the end plate or the end body should be installed, which also reduces the elementary effect of the flow field of the wing, reduces the effect of the end plate, and improves the lift-to-drag ratio of the full-bomb. If the end plate end body is not used, the lower anti-swept wing can be used to ensure that the wing end is close enough to the water surface, so that the range and strength of the wing end vortex are reduced.
3.2 The design of the control surface of the control surface is very important for the safety of the sea-effect missile. The following characteristics should be noted in the design: (1) The elevator elevator is the most important control surface of the sea-effect missile, because the missile must enter or exit the ground effect area. Operate by the elevator.
Outside the ground effect area, the elevator should be able to generate sufficient pitching moment when deflecting to ensure that the missile can safely enter or exit the ground effect area according to control requirements under various sea conditions. In order to improve the efficiency of the operation, the trailing edge rudder is used.
The flap-like flying missiles have no flaps. When cruising in the ground effect zone, the lift value of the wing pad has a great relationship with the shape of the underside of the wing and the distance from the trailing edge of the wing to the sea surface. If the flaps are installed on the wing and the appropriate angle is adjusted, the shape of the lower airfoil and the distance from the sea edge to the sea surface can be controlled to maximize the lift of the mat.
The ailerons and the sea surface flow are not disturbed, and the left-hand flow field of the wing cannot be completely symmetrical. When the direction of flight of the sea-effect missile in the ground effect area is approximately 90 with the direction of wave propagation, the asymmetry of the left and right flow fields of the missile is the most serious. Asymmetry in the flow field leads to asymmetry in lift. The resulting rolling disturbance torque must be balanced by the +-off deflection aileron. Since the end plates or end bodies are to be installed at both ends of the wing, the ailerons cannot be placed at the wing tips.
The natural frequency of the natural frequency control surface is automatic. 3 The frequency of the missile is reduced. The frequency of the missile is reduced. The number of flying waves per second should not be 3.3. The ground effect produced by the body is very small. The design principle is the same as that of the 6-air missile.
4Aerodynamic layout research and flight parameter design 4.1 Layout basis and principle The basis of the aerodynamic layout of the sea-effect missile is still the missile's technical indicators. The main target is the missile's range cruise speed and the high launch conditions using the sea conditions; The difference between aeronautical missiles is that cruising altitude is the most important basis for aerodynamic layout.
In the case of the sea-effect missile, it is necessary to cruise in the ground-effect zone. In addition, it must first experience free space before entering the ground-effect zone. At the same time, it may also have to cruise outside the ground-effect zone when using high sea conditions. The characteristics of both free space and ground effect areas. The biggest characteristic of the 6 lines in the area of ​​the effect area is that the longitudinal static stability of the missile changes sharply with the height of the 6 lines, and the height range of the ground effect area is very small. Therefore, the principle of the layout of the sea effect missile is to ensure that the ground effect area has both inside and outside the area. Necessary stability and maneuverability.
4.2 The layout type is to ensure that the ground effect area has 6 high stability, and the ground effect aircraft, the sea effect missile like the normal layout. There are several schemes for the flat tail arrangement. The flat tail is placed outside the ground effect area, that is, the high flat tail arrangement is adopted.
The flat tail is in the ground effect zone, but has a negative mounting angle; or the wing has a positive mounting angle and the flat tail has no mounting angle.
Move the flat tail to the no-wash zone beyond the tip of the wing.
If the missile is to be hung up or launched from underwater, the layout of the high flat tail is difficult to achieve. It is also difficult to move the tail to the outside of the wing under the underwater launch.
In order to utilize the engine jet, the engine should be installed at the front end of the wing, so that the jet generated by the engine can flow between the bottom of the wing and the water surface to form a wing. The engine can also be mounted on the vertical tail to avoid the effects of seawater splashing on the engine.
In order to avoid different 0 degrees of motion such as pitch and sink and float coupling, the full-elastic centroid should be placed as close as possible to the lift point of the change. The position ratio of the flat tail and the mounting angle should be chosen so that the pitching moment around the center of gravity is balanced and the pitch stability is also ensured outside the ground effect zone.
4.3 Cruise height design From theory 1 and the lower the cruising altitude, the higher the lift-to-resistance ratio, the better the 6-line concealment, which should be the goal pursued by the design. However, when cruising in the sea surface area, the sea surface disturbance will cause the 6-line missile to deviate from the set cruising altitude. The higher the sea level, the higher the wave height deviates from the Tongyue people; if the giant deviation exceeds the cruising altitude, the missile may City water. Therefore, the cruising altitude should be determined according to the actual use of the sea. The height design must be noted that in the ground effect area, the lift increases with the decrease of the height, the critical point, and the lift point decreases after the critical point. In addition, the height is too small, which makes the longitudinal static stability too human, thus causing the missile to be effective. Okane is difficult. The oscillation is unstable, affecting 6 lines of safety. 1 4.4 leveling angle of attack in the ground effect area, only 6 angles of attack angle missiles may have 6 high stability. The design of the flat 6 angle of attack is mainly determined according to the mass cruising speed of the missile and the aerodynamic characteristics of the bomb. The level 6 angle of attack should be small and unpleasant, and the aerodynamic force generated by the angle of attack can maintain a linear relationship with the angle of attack. At the same time, the floor mat effect will not be destroyed under the small angle of attack. It is also possible to maintain a linear relationship with the 6 high, so that it is beneficial to the manipulation of the missile.
4.5 Mutual Coordination in Design The design of missile parameters and combat technology indicators are dependent on each other. Different parameters or different indicators will also have mutual influence. Therefore, the parameter design process must be coordinated with each other or with the requirements of combat technology indicators. For example, when the cruising altitude and the angle of attack are set, it is not only necessary to verify whether the stability and pitch stability of the missile 6 meets the requirements, but also whether the missile has speed stability at the specified cruising speed. To complete a good shape and layout design, this coordination often has to be repeated many times.
8 Guo Yi, Zhou Danjie, Xu Zhiguo, Research on linear unsteady aerodynamic calculation method. Department of China Aerospace Electromechanical Corporation, 2000.5 Lu Guoxin, Zhou Danjie, Research on Longitudinal Stability and Maneuverability of Sea-effect Missiles. China Aerospace Electromechanical Collectives Department, 2000.7
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