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IBL Design Activity (CD Supersonic Wind Tunnel): In propulsion, we deal a lot with supersonic applications, and it is always desired to subject a test object to the flow conditions that the object will undergo in actual flight. This requires a supersonic wind tunnel that can be constructed by allowing air entering at atmospheric pressure to pass through a CD nozzle into a vacuum tank as shown below. With this setup, constant conditions are maintained in the test section until the pressure in the tank rises to a value such that a normal shock appears in the test section, the biggest challenge is how to delay the appearance of the normal shock and provide a longer running time at the design Mach number. PR co Nette www lich a) For a range of supersonic design Mach numbers (M = 1 to 3) at sea level (P = 101325 pa and T=20 C°). Find the maximum running time to maintain uniform conditions in the test section before a shock appears if the test run started with a pressure of zero in the tank. The wind tunnel test section to be circular of 10 cm diameter and the tank volume is 2 m. Assume isentropic flow everywhere except across the shock (no boundary layer or friction effect). * You are required to show all equations and results tabulated for the indicated range of design Mach numbers. * Plot the design Mach numbers against the running time to maintain uniform conditions. * Comment on the results. b) Plot in the same graph the design Mach numbers against the running time to maintain uniform conditions for multiple tank volumes (2,4 & 6 mº). Comment on the results. c) What are the main parameters that could affect the running time of the wind tunnel maintaining uniform conditions? d) Provide a sample calculation of your results for M=2.