Abstract
The variation of composition with position in the exhaust jets of model rockets operated in a large wind tunnel has been measured at selected simulated altitudes and freestream conditions. Measurements were obtained only far downstream from the nozzle exit. Samples were withdrawn from the exhaust by means of a cooled probe and analyzed by the use of a mass spectrometer. Data obtained at sea level with zero freestream velocity are in reasonably good agreement with theoretical predictions based on the behavior of low-speed jets and of isoenergetic high-speed jets in the region where data were taken. The apparent origin of the far-field flow is considerably displaced (in a downstream direction) from that predicted by current theories of jet mixing. Data from the observed region agree with the results of a linearized far-field theory that assumes constant-pressure mixing and confirms the downstream displacement. Nomenclature a — sonic velocity c* — characteristic velocity DT = eddy diffusivity H = total enthalpy h = static enthalpy M_ = Mach number M = average molecular weight p = pressure R = 0/F ratio r = radial coordinate THI = jet half-radius SCT = turbulent Schmidt number T = temperature u = velocity wex = mass fraction of exhaust gases -Xequiv = axial coordinate defined by Eq. (2) x = axial coordinate y — mole fraction Z = altitude r = any mean flow quantity AT = temperature difference from freestream e = area ratio of nozzle r} — similarity variable, r/x p = density Subscripts and superscripts c = j et centerline e = freestream j = nozzle exit plane conditions n = conditions for the jet isentropically expanded to ambient pressure * = Howarth-plane or incompressib le variable
Published Version
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