Abstract
Numerical study into the effects of area contraction on shock tube performance has been reported in this paper. The shock tube is an important component of high speed fluid flow test facility was designed and built at the Universiti Tenaga Nasional (UNITEN). In the above mentioned facility, a small area contraction, in form of a bush, was placed adjacent to the diaphragm section to facilitate the diaphragm rupturing process when the pressure ratio across the diaphragm increases to a certain value. To investigate the effects of the small area contraction on facility performance, numerical simulations were conducted at different operating conditions (diaphragm pressure ratios P4/P1 of 10, 15, and 20). A two-dimensional time-accurate Navier-Stokes CFD solver was used to simulate the transient flow in the facility with and without area contraction. The numerical results show that the facility performance is influenced by area contraction in the diaphragm section. For instance, when operating the facility with area contraction using diaphragm pressure ratio (P4/P1) of 10, the shock wave strength and shock wave speed decrease by 18% and 8% respectively.
Highlights
A short duration high speed flow test facility is an apparatus used to generate gas flow conditions of high enthalpy and high Mach number for a very short duration
From this Figure, it is possible to follow the physics of the flow inside the shock tube
The shock wave compresses and heats the test gas as it is traveling towards the end of the shock tube, and subsequently reflects off at the closed end of the driven section to further compresses the test gas and increases its pressure to around 450 KPa
Summary
A short duration high speed flow test facility is an apparatus used to generate gas flow conditions of high enthalpy and high Mach number for a very short duration (in the order of milliseconds). Such facility includes shock tube, shock tunnel, plasma jet, arc heated tunnel, free piston tunnel, and gun tunnel [1]. A numerical study using a finite volume based code was performed by Jacob et al [7] In their study, they simulated the shock reflection process in an axi-symmetric shock tube and a high Mach number nozzle using a perfect gas with no boundary layers applied on the shock tube walls. For more details on the solver, refer to References [9, 10]
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