PRESSURE FLUCTUATIONS RESULTING FROM AN ALTERNATING FLOW SEPARATION AND ATTACHMENT AT TRANSONIC SPEEDS

Abstract

Abstract : Investigations of unsteady pressures on conecylinder bodies at transonic Mach numbers were conducted in the Propulsion Wind Tunnel Facility (PWT). Static and unsteady pressure measurements were obtained for cone- cylinder bodies with cone half angles of 15, 20, 25, and 30 deg to determine characteristics of the various unsteady flow phenomena. This report presents a detailed analysis of the alternating separation and attachment flow phenomenon that occurs at the shoulder of the cone-cylinder. Results of this analysis indicate that from the static pressure distributions, one may determine the regions of the model to be subjected to unsteady loads, the free-stream Mach number at which this will occur, and the peak-to-peak and root mean square amplitude of these loads. The magnitude of the pressure fluctuations ranges from 0 to 43 percent of the free-stream dynamic pressure, depending on cone angle, angle of attack, and position on the model surface, which correlates with predicted magnitudes from static pressure measurements. (Author)