Analysis of aerodynamic forces and moments by a single video camera and its application to falling motion of bowl-shaped body

Abstract

The method to know aerodynamic forces and moments acting on a flight body in unsteady motion by a single video camera was developed in the research. The location and posture of the body was decided by the correlation method similar to that of the particle tracking velocimetry with the addition of the flight body rotation. Since the body location and attitude gained from a picture image essentially has an optical apparent error, it was modified to get more precise aerodynamic forces and moments loaded on the body The experimental results for the certainty of the method indicated that the location of the body could be gained within the error of ±1.5 mm on the picture plane perpendicular to the optical line and the rotation angle of the body within the error of it 3° . The position of the body in the direction of the optical line could although be measured with larger error. This method was applied to the falling motion of a bowl-shaped reentry body in the wind tunnel, the exit of which was directed upward After calculating the location and attitude of the body by the single camera method, the results were approximated by polynomials to get the external forces and moments by the derivative action. Furthermore, the data for the ground axes system were converted to these of the body axes system. It was found from the converted data excluding the effect of the gravity that the oscillating aerodynamic side-forces were loaded onto the body with the immediate reduction of the amplitude, and the reentry body fell into the stable posture with balancing the longitudinal