Wall Pressure Fluctuations on a Cone-Cylinder Model at Transonic Regime

Flow induced vibrations and interior noise are inevitable issues for aerospace vehicle design. Panel vibrations under fluctuating pressure excitation can cause fatal damage to aerospace vehicle structures. In order to identify the characteristics of wall pressure fluctuations, wind tunnel test using a cone-cylinder model is performed. The test is conducted at transonic Mach numbers and for variable angle of incidence which are the most critical in terms of occurrence of flow instability. The root-mean-square values of fluctuating pressures (Prms) reveal that the ogive of cone-cylinder is usually critical region to encounter large Prms values as flow separation occurs here. Also, at large mach numbers, shockwave arises on the cylinder and moves downstream as upstream flow speed increases. At transonic regime the shockwave is usually unstable and easily oscillating, which induces severe flow conditions around the cylinder. The test suggests that shockwave oscillation and flow separation are the typical environments which induce large fluctuating pressures. Mach number is the key parameter to influence flow condition as it determines the strength of flow separation and shockwave instability. Angle of incidence appears not to influence the fluctuating pressure significantly.