The effect of magnetohydrodynamic (MHD) plasma actuators on the control of hypersonic shock wave/turbulent boundary layer interactions is investigated here using Reynolds-averaged Navier-Stokes calculations with low magnetic Reynolds number approximation. A Mach 5 oblique shock/turbulent boundary layer interaction was adopted as the basic configuration in this numerical study in order to assess the effects of flow control using different combinations of magnetic field and plasma. Results show that just the thermal effect of plasma under experimental actuator parameters has no significant impact on the flow field and can therefore be neglected. On the basis of the relative position of control area and separation point, MHD control can be divided into four types and so effects and mechanisms might be different. Amongst these, D-type control leads to the largest reduction in separation length using magnetically-accelerated plasma inside an isobaric dead-air region. A novel parameter for predicting the shock wave/turbulent boundary layer interaction control based on Lorentz force acceleration is then proposed and the controllability of MHD plasma actuators under different MHD interaction parameters is studied. The results of this study will be insightful for the further design of MHD control in hypersonic vehicle inlets.
In order to accurately simulate the aerothermal environment of hypersonic vehicles, research on the grid convergence and influence of wall temperature is conducted in this paper. Two kinds of gas models are utilized for numerical simulations, namely the thermochemical non-equilibrium gas model and the perfect gas model. A typical hypersonic vehicle-the Orbital Reentry Experiment capsule-is used as the simulation object. After designing a series of coarse and refined grids, numerical simulations are conducted with the two gas models under different wall temperatures. Results indicate that the heat transfer prediction is very sensitive to normal grid spacing at the wall. Grid convergence for the two gas models is basically the same. When the grid is convergent in the hypersonic flow heat flux calculation, the required normal height of the first layer is smaller for the low wall temperature condition, compared with the high wall temperature case. Moreover, when the grid-convergence requirement is met, the heat flux increases with the reduction of wall temperature for all of the simulated flight conditions.
Under the assumption of the low magnetic Reynolds number, the coupled model is established for the turbulent flow field and the externally applied magnetic field. The AUSMPW+ scheme and LUSGS method are used to solve turbulent MHD flow equations, in which the Spalart-Allmaras one-equation turbulence model is used. A series of numerical simulations over various geometry configurations, namely, a flat plate and a compression corner, is conducted by using an external electromagnetic field. Results show that the performance of MHD boundary layer flow control is determined mainly by the Lorentz force in the streamwise direction. With an external magnetic field used,the low velocity fluid in the boundary layer can decelerate and increase the static temperature locally. Moreover, the counter-flow Lorentz force always brings a negative effect on the turbulent skin friction coefficient, and the location for the MHD zone has a great influence on the control efficiency of the ramp-induced separation. A reasonable magnetic field layout scheme should be configured in practical engineering application.
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