Hypersonic Flow and Shock Wave Structure Control by Low Temperature Nonequilibrium Plasma of Gas Discharge

Abstract

Shock wave -non-equilibrium plasma interaction is investigated and analysis of possible gas dynamics drag reduction under such conditions is provided. Experiments with controlled excitation of the translation-rotational and vibration electronic degrees of freedom of the gas by non-equilibrium glow discharge stabilized by gas flow in the hypersonic nozzle and investigations of the possibility of shock wave structure control by non-equilibrium plasma were performed. Stagnation pressure decrease up to 15%was determined for air flow at M=8.2. Temperature measurements shows the temperature increase due to gas excitation in the discharge and internal degrees of freedom relaxation. The conclusion was made that the gas discharge affects the flow mainly by thermal heating in the investigated range of parameters. Calculations support the conclusion about the thermal nature of the shock wave-plasma interaction.

Shock wave refraction enhancing conditions on an extended interface

“…Examples would include high voltage glow discharge stabilized by the gas flow at ultra-high overvoltage. 16 In general, the presence of plasma in this process is not necessary because the refraction phenomena does not include charged particles and will work in case of any thermal media. Based on this, the findings can be used to interpret or describe qualitatively the shock front transformations…”

“…The changes existed for significant time (on the order of 1 ms) after the discharge was terminated. 16 In deciding what kind of mechanisms are contributing to the shock dispersion, it is important to determine if the gas dynamic flow is in thermal equilibrium or not. While the energy transfer processes on a molecular/atomic level (such as electronic excitation, vibrational excitation or relaxation, chemical reactions, ionization and dissociation, or radiation) can significantly contribute in nonequilibrium, the pure thermal mechanisms would be more important in the flows with established local equilibrium.…”

The cumulative energy effect for improved ignition timing

“…1-13 Significant shifts in the timing of interaction between a shock and a media are also observed as the continuing changes in the shock front structure after the discharge is off, or still observable shock front modifications after the shock wave leaves the discharge area. 14 The most common result of interaction between the shock and gas inhomogeneities is the shock wave acceleration. 15 Depending on the specific gas state, geometry of the interaction, and the gas parameter distribution, it can also decelerate until its full stop.…”

“…The thermal plasma/gas regions are always present, for example, in the energy deposition experiments and they are described, in the absence of diffusion, as nonuniform gas objects, with a temperature profile for the initial temperature distribution that can be approximated with a Gaussian function. 23 The effects of the shock-plasma interaction have been an area of interest mostly due to its applications in aerospace for aerodynamic flow control in supersonic flights and for atmospheric reentry; 14,[24][25][26][27][28][29][30][31][32][33][34][35] in MHD for shock wave structure control; in astrophysics for shock waves generated in stellar interior; 15,16 and in environmental science for sonic boom suppression. Another area of considerable interest is the shock wave assisted combustion, where a shock wave can be used to affect the ignition conditions in the gas.…”

Nonequilibrium Plasma Aerodynamics

“…The clarification was done in papers [Khorunzhenko et al, 2003;Anokhin et al, 2004]. Papers [Khorunzhenko et al, 2002[Khorunzhenko et al, ,2003] describe the results of measurements of the structure of the strong shock waves in plasma with strong electric fields (E/n ~ 10 kTd). The authors obtained profiles of gas rotational temperature, distribution of electron number density and electric field in air flow at M = 8.2.…”