A tail-swinging trajectory capturing test method

Abstract

The application discloses a tail-rotation type trajectory capturing test method, and aims to establish a trajectory capturing test capability of simulating a tail-rotation separation process of a separated body from a parent body in a wind tunnel, and belongs to the technical field of wind tunnel tests. The method comprises the following steps: a capturing trajectory technology that the separated body rotates around a tail fixed shaft, a technology that the separated body is switched from rotating around the fixed shaft to unconstrained rotation around the center of mass at a moment of unhooking, and a capturing trajectory technology that the separated body is in unconstrained free motion. The test is carried out by adopting the capturing trajectory method, and the trajectory and the attitude angle change of the separated body during the tail-rotation separation process from the parent body can be obtained, which is helpful to judging the safety and compatibility of the two-body separation. The method has the advantages of high simulation data precision and reliable data.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of experimental aerodynamics, and particularly relates to a tail-rotation type capture trajectory test method. BACKGROUND

[0002] Capture trajectory test (CTS) is a commonly used wind tunnel test method for aircraft / missile separation, which has the advantages of high prediction accuracy, can obtain test results basically consistent with full-size flight test data, can simulate complex separation conditions and special flight states of the external store by computer software in the test, such as pitch, climb or acceleration flight, etc., can adapt to the launch under certain envelope flight states of the aircraft, can directly give the separation trajectory of the external store in the test, and can timely evaluate the separation characteristics. The test can not only obtain the separation trajectory under full-size conditions, but also can directly measure the aerodynamic load of the external store at each measurement point on the separation trajectory, which is beneficial to the analysis and improvement research of the external store separation characteristics. In view of such advantages, it is a necessary aircraft / external store compatibility verification project before carrying out flight test.

[0003] The CTS wind tunnel test technology originated in the United States in the 1950s. Bamber of the David Taylor Naval Ship R&D Center initially adopted the CTS test system to conduct grid force measurement of a certain aircraft under missile, and later developed into closed-loop control, including the 4-inch transonic continuous wind tunnel of AEDC in the United States, the 4-inch supersonic wind tunnel of VKI, etc., which are mainly used to study the separation problems of external stores suspended on the wings or the belly, such as the CTS test of F / A-18C aircraft launching JDAM missile. Subsequently, the CTS test technology is also gradually used to study the separation of internal weapons, the separation of space vehicles and weapon systems in series / parallel stages, such as the F-35 fighter aircraft launching internal bomb bay, the B-1B bomber launching GBU-38 missile from bomb bay, and the Ares I-X rocket stage separation.

[0004] Traditional separation and launch problems are generally unconstrained / segmented for the separation body itself, including initial launch speed / angle, ejection force / ejection stroke, thrust, maneuvering (with overload) launch, etc. Such problems can be effectively simulated by the existing CTS test technology, but for the capture trajectory wind tunnel test under complex constraint conditions, such as the tail-rotation type separation problem of the aircraft launching auxiliary fuel tank, the space vehicle shedding the head fairing, etc., which first rotates around the fixed axis, and the separation body is completely separated after exceeding a certain angle, the solution is not mature. SUMMARY

[0005] The tail-turning type capture trajectory test method provided by the application meets the capture trajectory wind tunnel test requirements of the multi-section tail-turning separation problems such as the aircraft auxiliary fuel tank and the spacecraft head fairing, and has the advantages of high simulation data precision and reliable data.

[0006] The tail-turning type capture trajectory test method comprises: tail-turning movement of a separation body model; unhooking movement of the separation body model; and free movement of the separation body model.

[0007] In the tail-turning type capture trajectory test method, the tail-turning movement of the separation body model comprises: at the beginning of the test, the separation body model is moved to an initial position and an initial attitude by using a six-degree-of-freedom movement mechanism, the aerodynamic force and the aerodynamic moment of the separation body model at an initial time t0 are obtained by using an internal five / six-component force balance, and a restricted movement equation solution of the tail-turning movement is performed according to the aerodynamic force and the aerodynamic moment of the separation body model at the initial time t0 and preset parameters of the separation body model, so as to obtain the angular displacement, the angular velocity, the angular acceleration and the position of the separation body model at a next time t1 in the wind tunnel.

[0008] In the tail-turning type capture trajectory test method, the unhooking movement of the separation body model comprises: step S21: the position of the separation body model at the next time t1 is sent to a movement mechanism control system, the movement mechanism control system controls the six-degree-of-freedom movement mechanism to perform the tail-turning movement of the separation body model according to the position of the separation body model at the next time t1, and a position signal is sent to a wind tunnel measurement and control system after the separation body model is positioned. n When the tail-turning angle of the separation body model reaches or exceeds a preset unhooking angle, the rotation center of the separation body model is switched from the fixed axis of the separation body model to the center of mass of the separation body model, and the position, the linear velocity in three directions and the angular velocity in three directions of the center of mass of the separation body model at the time t n are obtained.

[0009] In the tail-turning type capture trajectory test method, the free movement of the separation body model comprises: step S31: the aerodynamic force and the starting moment of the separation body model at the time t n are obtained by using the internal five / six-component force balance, a six-degree-of-freedom movement equation solution is performed according to the aerodynamic force and the starting moment of the separation body model at the time t n and the preset parameters of the separation body model, so as to obtain the displacement, the attitude angle and the position of the separation body model at the time t n+1 ; the position of the separation body model at the time t n+1 is sent to the movement mechanism control system, and the movement mechanism control system controls the six-degree-of-freedom movement mechanism to drive the separation body model to perform the free movement to the time t n+1The position of the separated body model; step S32: repeating step S31 until the simulation time or the simulation stroke reaches the termination value.

[0010] In the tail-turning trajectory test method, the restricted motion equation of the tail-turning motion is:

[0011]

[0012] J z is the moment of inertia relative to the rotation axis, J zc is the moment of inertia relative to the z-axis around the center of mass, m is the mass of the separated body, l is the distance between the center of mass and the rotation axis, ω z is the angular velocity, t is the time, M zc is the moment of force of the aerodynamic force on the center of mass, g is the acceleration of gravity, θ is the angle between the center of mass and the horizontal axis x, and θ z is the rotation angle.

[0013] In the tail-turning trajectory test method, the time t n The position of the center of mass of the separated body model, the linear velocity in three directions, and the angular velocity in three directions are obtained by the following formula:

[0014]

[0015] X c , Y c , and Z c are the displacements of the center of mass of the separated body model in the X-axis, Y-axis, and Z-axis directions at time t n , θ , and φ are the pitch angle, yaw angle, and roll angle of the separated body in the separated body coordinate system, θ1 is the angle between the center of mass and the horizontal axis x at the unhooking moment, V xc , V yc , and V zc are the linear velocities of the center of mass of the separated body model in the X-axis, Y-axis, and Z-axis directions at time t n , ω xc , ω yc , and ω zc are the angular velocities of the center of mass of the separated body model in the X-axis, Y-axis, and Z-axis directions at time t n .

[0016] In the tail-turning trajectory test method, the preset unhooking angle is 20°.

[0017] In the tail-turning trajectory test method, the preset separated body model parameters include the mass, moment of inertia, and length of the preset separated body model.

[0018] The preset separation body model parameters include mass, moment of inertia and length of the preset separation body model.

[0019] In the tail-rotation type capture trajectory test method, the six-degree-of-freedom motion mechanism is connected to the tail end of the separation body model through the internal five / six-component force balance; the motion mechanism control system is connected to the six-degree-of-freedom motion mechanism; and the wind tunnel measurement and control system is connected to the motion mechanism control system.

[0020] Compared with the prior art, the present application has the following beneficial effects:

[0021] (1) The existing capture trajectory test is usually single-section type or unconstrained for the separation body, and the present application provides a multi-section type tail-rotation capture trajectory test method rotating around a fixed shaft, which widens the test capability.

[0022] (2) The present application provides a trajectory continuation technology that switches from rotation around a fixed shaft to unconstrained rotation around the center of mass at the instant of separation body unhooking, which can realize capture trajectory tests of two different motion types in a single test. BRIEF DESCRIPTION OF DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of preferred embodiments and are not intended to limit the scope of the application. Furthermore, the same reference numerals are used throughout the several views that appear on the drawings. In the drawings:

[0024] Figure 1 is a flow chart of the capture trajectory (CTS) test method for tail-rotation type provided by the embodiments of the present application;

[0025] Figure 2 is a schematic diagram of different stages of the capture trajectory test for tail-rotation type provided by the embodiments of the present application;

[0026] Figure 3 is a definition and schematic diagram of the coordinate system of the separation body rotating around a fixed shaft provided by the embodiments of the present application. DETAILED DESCRIPTION

[0027] Exemplary embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present disclosure are shown. It is to be understood that the present disclosure can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. It is to be understood that the embodiments and features of the present application can be combined with each other unless there is a conflict. The present application will be described in detail with reference to the accompanying drawings and embodiments.

[0028] Figure 1 is a flow chart of a test method for a tail turning form of a capture trajectory (CTS) provided by an embodiment of the present application. As shown in the figure, the method comprises the following steps: tail turning movement of a separated body model; unhooking movement of the separated body model; free movement of the separated body model. Figure 1

[0029] The tail turning movement of the separated body model comprises the following steps:

[0030] At the beginning of the test, the six-degree-of-freedom movement mechanism is used to move the separated body model to an initial position and an initial attitude, the aerodynamic force and the aerodynamic moment of the separated body model at the initial time t0 are obtained through the internal five / six-component force balance, and the restricted motion equation of the tail turning movement is solved according to the aerodynamic force and the aerodynamic moment of the separated body model at the initial time t0 and the preset mass, the moment of inertia and the length of the separated body model, so as to obtain the angular displacement, the angular velocity, the angular acceleration and the position of the separated body model at the next time t1 in the wind tunnel.

[0031] Specifically, at the beginning of the test, the six-degree-of-freedom movement mechanism is used to move the separated body model to an initial position and an initial attitude according to the test conditions. The aerodynamic force / moment of the test model is obtained through the internal five / six-component force balance, the obtained aerodynamic load data is received by the trajectory solving software, the restricted motion equation of the tail turning movement (rotation around a fixed axis) is solved, and the angular displacement, the angular velocity and the angular acceleration of the model at the next time in the wind tunnel are obtained.

[0032] The unhooking movement of the separated body model comprises the following steps:

[0033] Step S21: the position of the separated body model at the next time t1 is sent to the movement mechanism control system, the six-degree-of-freedom movement mechanism is controlled by the movement mechanism control system to perform the tail turning movement of the separated body model according to the position of the separated body model at the next time t1, and a position signal is sent to the wind tunnel measurement and control system after the separated body model is positioned;

[0034] Step S22: repeat step S21 until the time t n is reached, the tail turning angle of the separated body model has reached or exceeded the preset unhooking angle, the center of rotation of the separated body model is switched from the fixed axis of the separated body model to the center of mass of the separated body model, and the position, the linear velocity in three directions and the angular velocity in three directions of the center of mass of the separated body model at the time t n are obtained.

[0035] Specifically, the position command obtained by solving is sent to the movement mechanism control system, the tail turning movement of the separated body is performed by the movement mechanism control system according to the position command, and a position signal is sent to the wind tunnel measurement and control system after the separated body model is positioned. At this time, it is judged whether the tail turning angle of the separated body model in the wind tunnel reaches the unhooking angle, if not, the above process is repeated, and if yes, the unhooking movement of the separated body model is completed.​Figure 2 If the rotation angle of the model has reached or exceeded the unhooking angle, the rotation center needs to be switched from the rotation center to the mass center of the model in the trajectory calculation program at this time, which is Figure 2 The second stage in FIG. 2, the position and three directional linear velocities of the mass center of the model at the current time are obtained, as well as the three directional angular velocities of the model.

[0036] The free motion of the model includes the following steps:

[0037] Step S31: Obtain the aerodynamic force and starting torque of the model at time t n by the internal five / six component force balance, and perform six degree of freedom motion equation calculation according to the aerodynamic force and starting torque of the model at time t n , and the preset mass, moment of inertia and length of the model, to obtain the displacement, attitude angle and position of the model at time t n+1 ; send the position of the model at time t n+1 to the motion mechanism control system, and the motion mechanism control system controls the six degree of freedom motion mechanism to drive the model to perform free motion to the position of the model at time t n+1 ;

[0038] Step S32: Repeat step S31 until the simulation time or simulation distance reaches the termination value.

[0039] Specifically, the aerodynamic force / torque of the model is obtained by the internal five / six component force balance, and the trajectory calculation software receives the obtained aerodynamic load data, at this time the trajectory calculation program uses the standard six degree of freedom motion equation to calculate the displacement and attitude angle of the model in the wind tunnel at the next time. Send the position command obtained by calculation to the motion mechanism control system, and the motion mechanism control system drives the model to move to the specified position according to the position command, as shown in the third stage in FIG. 2, repeat the above process until the simulation time or simulation distance reaches the termination value, complete the CTS trajectory line test. Figure 2

[0040] The six degree of freedom motion mechanism is connected with the tail end of the model through the internal five / six component force balance; the motion mechanism control system is connected with the six degree of freedom motion mechanism; and the wind tunnel measurement and control system is connected with the motion mechanism control system.

[0041] As shown in Figure 2 ​As shown, the tail-rotation CTS test consists of three stages: the first stage is the capture trajectory test technique 1, which involves rotation around a fixed axis; the second stage is the trajectory continuation technique 2, which involves the instantaneous switch from rotation around a fixed axis to unconstrained rotation around the center of mass after the separated body disengages; and the third stage is the capture trajectory technique 3, which involves the unconstrained free motion of the separated body. This test method uses a continuation approach to simulate the trajectory of the separated body throughout the entire process from tail rotation to unconstrained free motion.

[0042] (1) A capture trajectory test technique involving rotation around a fixed axis during the tail rotation phase 1;

[0043] (2) The moment of disengagement is the relay point. At the relay point, the trajectory continuation technique 2 is adopted, which switches from rotation around a fixed axis to unrestrained rotation around the center of mass.

[0044] (3) After unhooking, a general capture trajectory technique of free movement (unconstrained) of the separated body is adopted.

[0045] The capture trajectory test technique 1 only includes one degree of freedom, pitch motion, and its dynamic and kinematic equations are as follows:

[0046]

[0047] Among them, J z J is the moment of inertia relative to the axis of rotation. zc Let ω be the moment of inertia about the z-axis relative to the center of mass, m be the mass of the separated body, l be the distance between the center of mass and the axis of rotation, and ω be the moment of inertia. z ω is angular velocity, t is time, M is angular velocity. zc Let g be the torque of the aerodynamic force about the center of mass, g be the acceleration due to gravity, and θ be the angle between the line connecting the center of mass and the horizontal axis x. z For the rotation angle, such as Figure 3 As shown.

[0048] Time t n The position of the center of mass, the linear velocities in three directions, and the angular velocities in three directions of the separated body model are obtained using the following formulas:

[0049]

[0050] Among them, X c Y c and Z c Let time t n The displacements of the centroid of the separated model in the X, Y, and Z axes, θ, φ represents the pitch, yaw, and roll angles of the separated body in the separated body coordinate system, θ1 is the angle between the line connecting the center of mass and the horizontal axis x at the instant of disengagement, and V xc V yc and V zc Let time t nLinear velocity of the center of mass of the separated body model in the X-axis, Y-axis and Z-axis directions, ω xc yc zc Angular velocity of the center of mass of the separated body model in the X-axis, Y-axis and Z-axis directions, ω n Angular velocity of the center of mass of the separated body model in the X-axis, Y-axis and Z-axis directions, ω

[0051] The initial separation parameters of the three-stage trajectory capture technology of free motion are the parameters (position, attitude angle, velocity and angular velocity, etc.) at the time of unhooking, and the solving equation is the unconstrained six-degree-of-freedom kinematics and dynamics equation, and the test is completed after triggering the simulation time or the simulation stroke termination condition.

[0052] The separated body in the trajectory capture wind tunnel test adopts a tail support form, considering that the motion angle in the pitch direction usually exceeds 30°, in order to avoid the interference between the six-degree-of-freedom motion mechanism and the parent support mechanism, the tail support adopts a certain preset angle (-10° to -20°).

[0053] The existing capture trajectory test is usually single-section or unconstrained to the separated body, and the application proposes a multi-section tail rotation capture trajectory test method rotating around a fixed shaft, which widens the test capacity; the embodiment proposes a trajectory continuation technology that switches from rotating around a fixed shaft to unconstrained rotation around the center of mass at the unhooking moment of the separated body, and the two different types of capture trajectory tests can be realized in a single test.

[0054] Although the application has been disclosed as above with reference to the preferred embodiments, it is not intended to limit the application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the application by using the disclosed methods and technical contents without departing from the spirit and scope of the application, therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application, which does not depart from the content of the technical solutions of the application, all belong to the protection scope of the technical solutions of the application.​​

Claims

1. A tail-swinging trajectory capturing test method characterized by The method comprises: The tail turning motion of the detached body model; The unhooking motion of the detached body model; The free motion of the detached body model; The tail turning motion of the detached body model comprises: The test starts, the detached body model is moved to an initial position and an initial posture by using a six-degree-of-freedom motion mechanism, the aerodynamic force and the aerodynamic moment of the detached body model at an initial time t0 are obtained by using an internal five / six-component force balance, and a restricted motion equation solution of the tail turning motion is performed according to the aerodynamic force and the aerodynamic moment of the detached body model at the initial time t0 and preset parameters of the detached body model, so as to obtain the angular displacement, the angular velocity, the angular acceleration and the position of the detached body model at a next time t1 in the wind tunnel; The unhooking motion of the detached body model comprises: Step S21: the position of the detached body model at the next time t1 is sent to a motion mechanism control system, the motion mechanism control system controls the six-degree-of-freedom motion mechanism to perform the tail turning motion of the detached body model according to the position of the detached body model at the next time t1, and a position signal is sent to a wind tunnel measurement and control system after the detached body model is positioned. Step S22: repeat step S21 until time t n When the tail turning angle of the detached body model reaches or exceeds the preset disengagement angle, the center of rotation of the detached body model is switched from the fixed axis of the detached body model to the center of mass of the detached body model, and the time t n The position of the center of mass of the detached body model, the linear velocity in three directions, and the angular velocity in three directions; The free motion of the detached body model comprises: Step S31: Obtain the aerodynamic force and starting torque of the separation body model at time t n by the internal five / six component force balance, according to the aerodynamic force and starting torque of the separation body model at time t n , and the preset separation body model parameters, perform six-degree-of-freedom motion equation solving to obtain the displacement, attitude angle and position of the separation body model at time t n+1 ; send the position of the separation body model at time t n+1 to the motion mechanism control system, and the motion mechanism control system controls the six-degree-of-freedom motion mechanism to drive the separation body model to freely move to the position of the separation body model at time t n+1 ; Step S32: step S31 is repeated until the simulation time or the simulation stroke reaches a termination value. The restricted motion equation of the tail turning motion is: where J z is the moment of inertia about the rotation axis, J zc is the moment of inertia about the z axis through the center of mass, m is the mass of the separated body, l is the distance between the center of mass and the rotation axis, ω z is the angular velocity, t is the time, M zc is the moment of the aerodynamic force about the center of mass, g is the gravitational acceleration, θ is the angle between the line connecting the center of mass and the rotation axis and the horizontal axis x, θ z is the rotation angle.

2. The tail-swinging capture trajectory test method according to claim 1, characterized by: Time t n The position of the center of mass of the separating body model, the linear velocity in three directions, and the angular velocity in three directions are obtained by the following equations: where X c , Y c and Z c are the displacements of the center of mass of the separating body model in the X, Y and Z axis directions at time t n , θ and φ are the pitch, yaw and roll angles of the separating body in the separating body coordinate system, θ1 is the angle between the instantaneous center of mass and the center of rotation of the separating body at the instant of unhooking and the horizontal axis x, V xc , V yc and V zc are the linear velocities of the center of mass of the separating body model in the X, Y and Z axis directions at time t n , ω xc , ω yc and ω zc are the angular velocities of the center of mass of the separating body model in the X, Y and Z axis directions at time t n .

3. The tail-swinging capture trajectory test method according to claim 1, characterized by: The preset unhooking angle is 20°.

4. The tail-swinging capture trajectory test method according to claim 1, characterized by: The preset parameters of the detached body model include the mass, the moment of inertia and the length of the preset detached body model.

5. The tail-swishing capture trajectory test method of claim 1, wherein: The six-degree-of-freedom motion mechanism is connected with the tail end of the detached body model through the internal five / six-component force balance. The motion mechanism control system is connected with the six-degree-of-freedom motion mechanism. The wind tunnel measurement and control system is connected with the motion mechanism control system.

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