Peculiarities of the flows forming in processes of an impulse starting of a supersonic wind tunnel with different diffusers
Yu.P. Gounko, I.N. Kavun
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: сверхзвуковая аэродинамическая труба, сопло, диффузор, импульсный процесс запуска, нестационарное сверхзвуковое течение, supersonic wind tunnel, nozzle, diffuser, impulse starting process, unsteady supersonic flow
Abstract
The peculiarities of supersonic unsteady flows forming in the processes of an impulse starting of a wind tunnel including a fore-chamber, a nozzle, a diffuser, and an exhaust tank are considered. The fore-chamber is separated from the flow duct by a thin breakable diaphragm. Before the wind tunnel starting, the gas contained in the exhaust tank is pumped out down to a very small pressure, and then the high-pressured working gas is fed into the fore-chamber. Upon reaching some value of this pressure, the diaphragm “instantaneously” ruptures, and the working gas starts exhausting through the nozzle: a rapid unsteady process of the wind tunnel starting arises. The numerical simulation of the flows forming at the impulse starting of the simplest experimental gas-dynamic facility has been carried out; the facility is arranged with a nozzle forming at its exit a two-dimensional supersonic flow with the Mach number of 2.9, and with replaceable diffusers having different relative areas of the throat. The numerical computations of two-dimensional unsteady flows have been carried out using the Reynolds-averaged Navier-Stokes equations and the SST k-w turbulence model. The flow patterns computed numerically are compared with the data of the optical visualization of the flow obtained in the experimental gas-dynamic facility in the process of its starting.
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