A supersonic wind tunnel is a windtunnel which produces supersonic speeds(1.2<M<5) The first problem with a supersonic wind is to produce superonic speeds. This can be achieved with an appropriate design of a convergent divergent nozzle. The Mach number and flow are determined by the nozzle geometry. The Reynolds number is varied changing the density level (Pressure in the Settling Chamber). Therfor a high pressure ratio is required (for a supersonic regime at M=4, this ratio is of the order of 10). A part from that, condensation or liquefaction can occur. This means that a supersonic wind tunnel needs a drying or a pre-heating facility. A supersonic wind tubbel has a large power demand leading in only intermittent operation. This page is about high speed motion of bodies such as airplanes through air or other fluids. ... Mach number (Ma) (pronounced mack in British English and mock in American English) is defined as a ratio of speed to the speed of sound in the medium in case. ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ... The Reynolds number is the most important dimensionless number in fluid dynamics and provides a criterion for determining dynamic similitude. ...
Optimistic estimate: Pressure ratio the total pressure ratio over normal shock at M in test section:
Examples:
Reduction: The partial pressure recovery with convergent-divergent diffuser will lead into a reduced shock. This lead to losses with second throat.
Temperature effects: condensation
Temperature in the test section:
with T_t = 330K: T_m = 70K at M_m = 4
The Mach range is limited by reservoir temperature
Power requirements
The power required to run a supersonic windtunnel is enormous. It is in the order of 50MW per square meter of test section. For this reason most wind tubbels operate intermittently using energy stored in high-pressure tanks. These windtunnels are also called intermittent supersonic blowdown windtunnels (from which a schematic preview is given below). Another way of achieving the huge power output is with the use of a vacuum storage tank. These tunnels are called indraft supersonic wind tunnels. Other problems operating a supersonic windtunnel include:
enough supply of dry air
wall interference effects
fast instruments needed for intermittent measurements
the total pressure ratio over normal shock at M in test section:
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