An automated procedure for analyzing the effects of vortex-induced fin pressure on roll torque for a finned body of revolution.

Vijlee, Shazib Z.

Sandia National Laboratories

关键词: Data Analysis;    Torque.;    Pressure Measurement;    Aerodynamics;    Wind Tunnels;   

DOI  :  10.2172/919113
RP-ID  :  SAND2004-4378
RP-ID  :  AC04-94AL85000
RP-ID  :  919113

美国|英语

来源: UNT Digital Library

【 摘 要 】

In flight tests, certain finned bodies of revolution firing lateral jets experience slower spin rates than expected. The primary cause for the reduced spin rate is the interaction between the lateral jets and the freestream air flowing past the body. This interaction produces vortices that interact with the fins (Vortex-Fin Interaction (VFI)) altering the pressure distribution over the fins and creating torque that counteracts the desired spin (counter torque). The current task is to develop an automated procedure for analyzing the pressures measured at an array of points on the fin surfaces of a body tested in a production-scale wind tunnel to determine the VFI-induced roll torque and compare it to the roll torque experimentally measured with an aerodynamic balance. Basic pressure, force, and torque relationships were applied to finite elements defined by the pressure measurement locations and integrated across the fin surface. The integrated fin pressures will help assess the distinct contributions of the individual fins to the counter torque and aid in correlating the counter torque with the positions and strengths of the vortices. The methodology produced comparisons of the effects of VFI for varying flow conditions such as freestream Mach number and dynamic pressure. The results show that for some cases the calculated counter torque agreed with the measured counter torque; however, the results were less consistent with increased freestream Mach numbers and dynamic pressures.