Asymptotic Solutions of Normal Shock Wave Structured by Nonequilibrium Radiative and Collistional Ionization PDF Download

Author: Brown University
Publisher:
ISBN:
Category :
Languages : en
Pages : 83

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Author: Brown University. Division of Engineering
Publisher:
ISBN:
Category :
Languages : en
Pages : 67

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Author: Joseph Henry Clarke
Publisher:
ISBN:
Category :
Languages : en
Pages : 87

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Normal shock waves structured by nonequilibrium radiative and collisional ionization are solved analytically. On the basis of current literature, an earlier radiation model for monatomic gases is generalized to include the second continuum with the first continuum and the lines; in the model, the one-step radiative ionization process of interest is interior to a much thicker region only weakly structured by the two-step radiative ionization process. Just downstream of the interior embedded discontinuity, it is assumed that electron-atom collisional ionization to local thermodynamic equilibrium occurs over a length that is small compared with the relevant one-step photon path. It is discovered that the appropriate emmission-convection ratio is also a rather small quantity. Both small quantities lead to iterations studied to second approximation. The resulting shock morphology consists of a strong precursor, the embedded discontinuity, an inner collisional tail, and an outer radiative tail. The interaction of the two small parameters requires certain final reinterpretations. Calculations for helium and argon are presented for a downstream degree of ionization of 0.8, an upstream temperature of 300K, and upstream pressures of .001, .0001, and .00001 atmospheres. (Author).

Author: Carlo Ferrari
Publisher:
ISBN:
Category :
Languages : en
Pages : 40

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The general theory about gas-dynamics with nonequilibrium radiative and collisional ionization is applied to the strong normal shock wave. It is shown that the problem is reduced to the solution of a system of two non-linear integral equations. It is proved that, if certain conditions are satisfied, an iteration method, to resolve these equations, can be applied; it turns out then that the fundamental parameter controlling the convergence or non convergence of the procedure is the value of the degree of ionization just on the front of the shock. Numerical results are given and the physical complete structure of the shock is analyzed. (Author).

Author: Joseph Henry Clarke
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ISBN:
Category : Radiation
Languages : en
Pages : 18

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Author: William Henry Foley
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

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Ionizing shock waves in helium and argon are structured by nonequilibrium radiative and inelastic collisional transitions. The model atom of the monatomic gas has three electronic energy levels. The monatomic gas is not in local equilibrium with respect to population, and local translational equilibrium between the heavy species present and the electron gas is not assumed either. For the flow conditions studied the physics and morphology of the shock is further developed on a continuum basis from previous work, and the shock is found to consist of a far precursor due to radiative excitation, a near precursor due to radiative ionization, an embedded transport shock, an inelastic and thermal collisional relaxation zone, and an equilibrium radiating tail. Of particular interest in the results are the heating of the electron gas in the precursor by the said radiative and the associated de-exciting collisional mechanisms and the subsequent, electron-triggered collisional relaxation zone which is optically transparent to radiation; thus, nonequilibrium radiative and collisional processes are locally uncoupled throughout the shock. A family of numerical examples are displayed diagrammatically for an upstream temperature of 300 degrees K and upstream pressures bbetween 1/1000 and 1/100,000 atmospheres. Selected were those accompanying downstream temperatures giving nominal equilibrium degrees of ionization of either 0.8 or 0.95. (Author).

Author: Martin Philip Sherman
Publisher:
ISBN:
Category : Radiation
Languages : en
Pages : 62

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The problem of a normal shock wave in air or other gas with complex chemistry and coupled radiation is considered. Molecular transport properties are neglected and the gas mixture is assumed in translational, rotation, vibrational and electronic equilibrium with the local temperature. Only continuum radiation is included. Solutions are presented for strong shock waves in air, where air is assumed to consist of eleven species, N2, O2, O, NO, NO+, N+, O, N2+, O2+ and electrons. The usal methods of integrating the stiff ordinary differential equations of chemical nonequilibrium flow are limited to very small step sizes. Methods are developed which permit vastly larger step sizes. Solutions are obtained for the optically thin case, and with absorption of radiation behind the shock front. The spectrum is broken into regions inside of which the absorption cross sections are only a function of temperature. (Author).

Author: Maheshinder Singh Grewal
Publisher:
ISBN:
Category : Ionized gases
Languages : en
Pages : 160

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The structure of a shock wave in a partially ionized gas, which is in thermal on-equilibrium ahead of the shock wave, is investigated. A method is developed to solve this problem by separating it into two parts. First the structure of the shock wave associated with the mixture of ions and atoms, which are assumed to behave alike through the shock transition, is taken to be of the Mott-Smith form. Then the behavior of electrons as they pass through this ion-atom shock is analyzed. Using this method, calculations are made for the shock wave structure in partially ionized argon for Mach numbers equal to 8, 10 and 12, and for the values of the lectron-ion temperature ratio ahe d of the shock wave equal to 3, 5 and 8. (Author).

Author: William M. Hilbun
Publisher:
ISBN: 9781423571810
Category : Ion acoustic waves
Languages : en
Pages : 274

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An analysis and assessment of three mechanisms describing plasma/ shock wave interactions was conducted under conditions typically encountered in a weakly ionized glow discharge. The mechanisms of ion-acoustic wave damping, post-shock energy addition and thermal inhomogeneities were examined by numerically solving the Euler equations with appropriate source terms adapted for each mechanism. Ion-acoustic wave damping was examined by modeling the partially ionized plasma as two fluids in one spatial dimension using the Riemann problem as a basis. Post-shock energy addition in the form of nonequilibrium vibrational energy relaxation was also examined in one spatial dimension using the Riemann problem as a basis. The influence of thermal inhomogeneities on shock wave propagation was examined in two spatial dimensions for both a Riemann shock and a shock generated by a spark discharge. Shocks were propagated through realistic thermal profiles with the resulting shock structure examined through the numerical application of various optical diagnostic techniques. Results from shock simulations indicate that ion-acoustic wave damping has an insignificant effect on the neutral flow at fractional ionization levels typical of glow discharges. Post-shock vibrational energy relaxation is also unable to effect the shock structure on the time scales of interest. An analysis of the effects of thermal inhomogeneities reveals that many of the observed plasma/shock anomalies can be explained based solely on this mechanism.

Author: Leroy L. Presley
Publisher:
ISBN:
Category : Chemical reactions
Languages : en
Pages : 10

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