Crossflow instabilities on a 2:1 elliptic cone in hypersonic flow have been investigated in the M6QT and ACE wind tunnels at the Texas A&M National Aerothermochemistry and Hypersonics Laboratory. Experiments on a PEEK 38.1% scale model of the HIFiRE-5 flight test geometry were conducted to investigate the development of crossflow instabilities as well as to characterize the freestream and surface conditions responsible for their initial amplitudes. The freestream environment was varied not only by testing the model in both quiet and conventional tunnels but also by passively changing the fluctuation levels experienced in the conventional facility through systematic model placement. ACE freestream measurements, using a Kulite pressure transducer mounted in a pitot probe configuration and a hot-wire anemometer, indicated that fluctuation levels at the upstream model station were half those at the downstream stations. Fast-response PCB and Kulite surface mounted pressure transducers allowed examination of pressure fluctuation amplitudes and
An experimental campaign was conducted to measure and to characterize the freestream disturbance levels in the NASA Langley Research Center 20-Inch Mach 6 Wind Tunnel. A pitot rake was instrumented with fast pressure transducers, hot wires, and an atomic layer thermopile to quantify the fluctuation levels of pressure, mass flux, and heat flux, respectively. In conjunction with these probe-based measurements, focused laser differential interferometry was used to optically measure density fluctuations. Measurements were made at five nominal different unit Reynolds numbers ranging from 3.28-26.5×10 6 /m. The rake was positioned at two different streamwise locations and several different roll angles to measure flow uniformity within the test section. In general, noise levels were spatially consistent within the tested region. Pitot pressure fluctuation levels ranged from 0.84% at the highest Reynolds number tested to 1.89% at the lowest Reynolds number tested. Freestream mass-flux fluctuations remained relatively constant between 1.8-2.5% of the freestream. The pressure transducers were also used to determine the dominant disturbance speed and angle of propagation. The disturbances were estimated to travel at approximately 54-81% of the freestream speed at an angle of approximately 21-44°from the freestream direction, but these measurements had a significant amount of uncertainty. A comparison to previous measurements of pressure made in 2012 and of mass flux made in 1994 show almost no change in the RMS fluctuation of these flow quantities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.