Accession Number : AD0675149
Title : ELECTRON DENSITY FLUCTUATIONS IN HYPERSONIC WAKES WITH DISSOCIATIVE-NEUTRALIZATION CHEMISTRY.
Descriptive Note : Research rept.,
Corporate Author : AVCO EVERETT RESEARCH LAB EVERETT MASS
Personal Author(s) : Schapker,Richard L.
Report Date : JUN 1968
Pagination or Media Count : 65
Abstract : A complete theory is presented for calculating electron density fluctuations, beginning in the near wake of bodies in hypersonic flight, for the case of dissociative-neutralization electron chemistry. Phenomenological diffusivity coefficients are used to relate turbulent transport of fluctuations to gradients in mean quantities. Allowance is made for variable properties along the wake boundary, and first-order compressibility effects are accounted for by using the Howarth-Dorodnitsyn transformation. Radial variations of flow properties are included through assumed Gaussian profiles in the compressible plane. The dissipation rate of electron fluctuations is obtained by integrating the conservation equation for turbulence kinetic energy. This approach, fully described in the text, yields the turbulence kinetic energy dissipation rate as well as velocity fluctuation levels and the energy-containing eddy size. Results obtained by integration of the coupled differential equations for mean and mean-square fluctuations of electron density are presented. Sensitivity to some of the input parameters is examined for a typical ballistic range case. It is shown that the ratio of rms fluctuation to mean electron density becomes constant in the region 500 to 1000 body radii. A comparison is made to ballistic range measurements, with satisfactory agreement. (Author)
Descriptors : (*ATMOSPHERE ENTRY, WAKE), (*WAKE, *ELECTRON DENSITY), DISSOCIATION, NEUTRALIZATION, DIFFERENTIAL EQUATIONS, COMPRESSIBLE FLOW, ANALYSIS OF VARIANCE
Subject Categories : Aerodynamics
Plasma Physics and Magnetohydrodynamics
Distribution Statement : APPROVED FOR PUBLIC RELEASE