The heat transfer rate was measured using global phosphor thermography and the resulting images and heat transfer rate distributions were used to infer the state of the boundary layer on the windside, leeside and side surfaces. Boundary layer trips were used to force the boundary layer turbulent, and a study was conducted to determine the effectiveness of the trips with various heights. The experimental data highlighted in this test report were used determine the allowable roughness height for both the windside and side surfaces of the vehicle as well as provide for future tunnel-to-tunnel comparisons.

No abstract

High-frequency pressure-fluctuation measurements were made in AEDC Tunnel 9 at Mach 10 and the NASA Langley 15-Inch Mach 6 and 31-Inch Mach 10 tunnels. Measurements were made on a 7 •-half-angle cone model. Pitot measurements of freestream pressure fluctuations were also made in Tunnel 9 and the Langley Mach-6 tunnel. For the first time, second-mode waves were measured in all of these tunnels, using 1-MHz-response pressure sensors. In Tunnel 9, second-mode waves could be seen in power spectra computed from records as short as 80 µs. The second-mode wave amplitudes were observed to saturate and then begin to decrease in the Langley tunnels, indicating wave breakdown. Breakdown was estimated to occur near N ≈ 5 in the Langley Mach-10 tunnel. The unit-Reynolds-number variations in the data from Tunnel 9 were too large to see the same processes. In Tunnel 9, the measured transition locations were found to be at N = 4.5 using thermocouples, and

No abstract

No abstract

No abstract

No abstract

Experiments have been carried out in the NASA Langley Research Center 20-Inch Mach 6Wind 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.