ABSTRACT
A facility that remains quiet to higher Reynolds numbers was therefore needed. The low operating costs of the Mach-4 tunnel had to be maintained. However, hypersonic operation was needed in order to provide experiments relevant to the hypersonic transition problems described above. Operation at Mach 6 was selected, since this is high enough for the hypersonic 2nd-mode instability to be dominant under cold-wall conditions, and high enough to observe hypersonic roughness-insensitivity effects, yet low enough that the re quired stagnation temperatures do not add dramatically to cost and difficulty of operation. Schneider (1998b) describes the overall design of the facility, and the detailed aerodynamic design of the quiet-flow nozzle, carried out using the e
N method.
