Shock Tunnels for Real Gas Hypersonics,
QUEENSLAND UNIV BRISBANE (AUSTRALIA) DEPT OF MECHANICAL ENGINEERING
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The application of free piston shock tunnels to the simulation of real gas effects in hypersonic flight is discussed. It is pointed out that the primary simulation variables for this purpose are the stagnation enthalpy and the binary scaling parameter. The free piston reflected shock tunnel is considered first, and it is shown how test time limitations play a major role in determining the limiting stagnation enthalpy for a given model size. Nevertheless, flight values of the two simulation variables, for vehicles similar to the Space Shuttle Orbiter, can be matched by an existing free piston shock tunnel up to speeds of 7 kms. Experiments performed in this shock tunnel are used to demonstrate real gas effects in model flows. Radiative energy loss limits the maximum stagnation enthalpy available with reflected shock tunnels. Fortunately, operation in the non-reflected mode circumvents this limitation and, in addition, allows higher values of the binary scaling parameter although it also leads to greatly reduced test times. The use of the prior steady flow technique to enable high enthalpy non-reflected shock tunnel operation is described, and examples of experiments performed in facility are used to demonstrate that short test times do not preclude worthwhile experimentation. A variant of the free piston shock tunnel, which is intended for propulsion research at high velocities, also is briefly described.
- Fluid Mechanics
- Test Facilities, Equipment and Methods