Pressure Fluctuation Measurements in the NASA Langley 20-Inch Mach 6 Wind Tunnel

Abstract

Experiments have been carried out in the NASA Langley Research Center 20-Inch Mach 6 Wind Tunnel to measure the freestream pressure fluctuations, or tunnel noise, using a pitot rake. These experiments are part of an on-going effort to characterize the freestream disturbances of the Langley hypersonic wind tunnels along with other facilities around the country. Once the freestream disturbances have been characterized, a better understanding of the effect of these disturbances on boundary layer instability and transition measurements can be gained. The current experiments use a multi-probe pitot rake instrumented with both Kulite and PCB pressure transducers. Data were obtained over a range of Reynolds numbers and test section axial and radial positions. In general, noise levels were consistent spatially across the test section and ranged from 1% at the highest Reynolds numbers tested to approximately 1.6% at the lowest Reynolds number tested.