Preliminary Study on Sonic Boom Measurement in Wind Tunnel Based on PIV Technique

A PIV technique-based measurement method of near-field sonic boom in wind tunnel has been proposed. Sonic boom which imposes restrictions on the development of supersonic transport is a peculiar acoustic phenomenon to supersonic flight. To verify the low boom design, measurements of near-field sonic boom are usually carried out in wind tunnels with pressure rails. The pressure rails introduce disturbances to flow fields. Furthermore, the rails are difficult to be fabricated and installed in small size wind tunnels. The near-field sonic boom is essentially formed by a series of shock and expansion waves. On this basis, the off-body pressure distributions can be obtained from the corresponding velocity field measured with PIV technique. Starting with an undisturbed point, flow parameters are calculated by the oblique shock wave formulas and the P-M expansion wave formulas respectively in compression regions and expansion regions, which are determined by the velocity magnitude. Numerical simulation has been conducted to validate the proposed measurement method. The calculated results are agreed well with the real results. Analysis of effects of parameters’ errors shows that the random errors of velocity magnitude have a significant effect on the sonic boom results.