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

Abstract

Microwave energy deposition is a novel method for flow control in high-speed flows. Experiments have demonstrated its capability for beneficial flowfield modification in supersonic flow including, for example, drag reduction for blunt bodies. A fully three-dimensional, time-accurate gas dynamic code has been developed for simulating microwave energy deposition in air and the interaction of the microwave-generated plasma with the supersonic flow past a blunt body. The thermochemistry model includes 23 species and 238 reactions. The code is applied to the simulation of microwave energy deposition in supersonic flow past a hemisphere cylinder. The computed centerline surface pressure is compared with the experiment. The interaction of the microwave-generated plasma with the flowfield structure is examined. Nomenclature c p i = specific heat at constant pressure for species i D = diameter of cylinder E, E o = electric field, maximum electric field H = total enthalpy per unit mass of mixture h o f i = heat of formation of species i at temperature T ref h i = static enthalpy of species i per unit mass of species i h = static enthalpy per unit mass of mixture K k = reaction coefficient for reaction k k = Boltzmann constant, 1:38 10 23 J=K k E = microwave wave number, 2= M = representative mass for ions and neutrals M i = molecular weight of species i, kg=kg mol M i = species i (e.g., M 1 e) M 1 = Mach number m = number of reactions m e = mass of electron N = total concentration of species excluding electrons, cm 3 N e , N crit e = electron concentration, critical electron concentration, cm 3 N i = concentration of species i, cm 3 n = number of species including electrons p = static pressure _ p i k = rate of production of species i from reaction k Fig. 1 Interaction of microwave-generated plasma with cylinder. Fig. 2 Centerline pressure vs time. _ q = rate of heating of gas per unit volume R = universal gas constant, 8314 J=kg mol K T = static (translational) temperature of mixture T e = electron temperature u i = mass-averaged velocity component in i direction V dr = drift velocity x i = Cartesian coordinate Y i = mass fraction of species i, Y i i = i = fraction of h i converted into heating of gas h i = rate of change in enthalpy due to reaction i = 2m e =M " = total energy per unit mass of mixture = wavelength of microwave = rotational relaxation factor, dimensionless e = effective frequency of electron collisions 0 ik , 00 ik

Joule heating flow control methods for high-speed flows

“…130 The thermochemistry model also allows the gas processes which result in the rapid heating to be better understood. The findings of Knight et al, 143 as shown in Figure 55, validated against experimental results show that this type of model can accurately model the impact of microwave energy deposition on high speed flows. The same model is used in a study by Knight et al 123 in an effort to replicate the experimental results of Kolesnichenko et al 122 The minimum achieved surface pressure of the numerical model showed excellent comparison to the experimental data, however the duration of this feature was debated.…”

“…So in effect, the ideal gas simulations are defining inputs based on previous experimental conditions rather than using the actual energy deposition input parameters themselves. 143 This would seem to indicate that the ideal gas simulations, although useful for the general study of microwave energy deposition, are somewhat limited by their inputs.…”

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 latter effect was named the vortex drag reduction. The reduction of drag force together with the decrease of the stagnation parameters was obtained experimentally and numerically for air, in particular, in [9][10][11]. Effects of a local heating on wave drag reduction were investigated in [12][13][14].…”

“…In the problems being discussed, changing the structures of the triple-shock configurations connected with physical-chemical transformations and characteristics of an energy source define a significant modification of dynamical and heat loadings on an AD body [9,10]. For strong shock waves when physicochemical reactions occur behind the shock fronts, the self-similarity assumption does not hold true because of relaxation effects.…”

A summary of laser and microwave flow control in high-speed flows

“…The inelastic collisions provide energy transfer through several di¨erent mechanisms including rotational excitation, vibrational excitation, excitation of electronic states, dissociations, and ionizations. The three main kinetic paths for energy transfer from these modes to the kinetic energy of the heavy particles (i. e., increasing the gas temperature) are rotational excitation, collisional quenching of the excited states, and electronion recombination [12].…”