Unsteady interaction of a sphere with atmospheric temperature inhomogeneity at supersonic speed

Abstract

The structure of the shock layer and the abrupt aerodynamic forces acting on a sphere moving in an atmosphere with inhomogeneous inclusions of various shapes are considered.Inhomogeneities of the medium, through which a body moves at supersonic speed, can produce considerable changes in the shape and structure of the leading shock wave. The motion of a sphere through a plane inhomogeneity was studied in various aerodynamic formulations in [1--8]. In [1--3] the problem of the penetration of blunt axisymmetric bodies (sphere-cone, sphere, and cylinder end-face) into gases with different aerodynamic properties was investigated using the Euler equations (the interaction with the shock wave was simulated). The flow in the vicinity of the stagnation streamline was considered in [4], with chemical relaxation behind the shock wave taken into account. The experimental results of [5] concern the flow past a smooth duralumin sphere moving at a speed of 1.98 kin/see through a region of heated air. In [6] a viscous shock layer model was applied to the axisymmetric flow upstream of a sphere moving through a high-temperature region. Inviscid non-heat-conducting supersonic flow through a medium with periodic stratified temperature inhomogeneity was numerically investigated in [7]. Threedimensional air flow with nonequilibrium reactions past a body entering a heated half-space was considered in [8].Hence considerable knowledge has been accumulated concerning the interaction between differently shaped bodies and plane inhomogeneities. However, closed (spatial) inhomogeneities of various kinds can also be created in the atmosphere. Plane shocks, passing through such regions, were studied experimentally and theoretically in [9--13].In [9] experimental data on a gas-dynamic pulse with a shock front passing through the decaying plasma of an electrodeless microwave discharge in air at medium pressure are given. Shock waves passing through the weakly ionized plasma of a laser spark late in its development in air at atmospheric pressure were experimentally studied in [10]. The shock wave was said to be eagerly absorbed in the "fireball" region. In [11] it was demonstrated that during the interaction of a shock wave with the hot region of a laser spark the shock wave front is accelerated and deformed due to the lens effect and then recovers, so that complete absorption of the shock wave [10] does not take place.The interaction of a plane shock wave with a spherical volume of hot gas was numerically investigated in [12] for the Reynolds number Re=50 using the complete Navier--Stokes equations. In practice, this problem corresponds to the interaction of shock waves with the hot gas cloud ejected by a volcano. The interaction of shock waves with spatial inhomogeneities of various shapes in an inviscid non-heat-conducting gas was numerically studied in [13]. In particular, the interaction of a plane shock wave with a cylindrical region of gas with relaxation was studied (in a model formulation). The interactions of a shock wave with a reactin...

Interaction of Microwave-Generated Plasma with a Hemisphere Cylinder at Mach 2.1

“…The principal effect of the interaction of a microwave-generated plasma with the flowfield surrounding a blunt body is thermal, that is, the effect of the interaction of a finite heated region with the flowfield structure (e.g., shock waves, expansions) generated by the aerodynamic body. Validation of this statement is provided by numerous ideal gas simulations (e.g., Georgievsky and Levin [9], Azarova et al [10], Farzan et al [11]) which have demonstrated drag reduction for the interaction of a finite heated region with a blunt body. However, in ideal gas simulations, the amount of energy deposited in the flowfield is parameterized by an assumed initial spatial distribution of thermodynamic properties (i.e., translational-rotational temperature and density) and velocity in a finite spatial region.…”

Control of Triple-Shock Configurations and Vortex Structures Forming in High Speed Flows of Gaseous Media past an AD Body under the Action of External Energy Sources

“…The first minimum in the curves is caused by a rarefaction wave reflection which is generated at the very beginning of the interaction process (see [8]). This rarefaction wave is an element of the solution of the Riemann problem which describes the interaction of the boundary of the heated area with the bow shock.…”

“…Energy sources of different types (microwave, laser, discharge) were used for these purposes [6,7]. Two mechanisms have been established causing this phenomenon, the reflection of a rarefaction wave from the body's surface [8] and the effect of a vortex structure generating via the interaction of an energy source with a bow shock [6]. The latter effect was named the vortex drag reduction.…”

Survey of Aerodynamic Drag Reduction at High Speed by Energy Deposition

“…Unsteady Energy Deposition 1. Levin (1993, 2004) Georgievskii and Levin [52] performed a series of Euler simulations at M 1 3 for the interaction of a thermal spot of various configurations with a sphere. The thermal spot originated upstream of the blunt body shock and was defined by a region of uniform reduced density s of the shape Fig.…”