A STUDY OF MOLECULAR SUPERSONIC-FLOW USING THE GENERALIZED BOLTZMANN-EQUATION

We report a model based on the generalized Boltzmann equation to predict the properties of a free-jet expansion of a single-component gas, with particular emphasis on polyatomic flow. Contrary to many other studies on this subject, we do not assume a constant beam speed. A new set of boundary conditions is obtained for the solutions to the moment equations which describe the evolution of the flow properties. The variation of the different temperature components, speed, and density as a function of distance is presented assuming an anisotropic Maxwellian distribution function. An expression for the bulk rotational relaxation time is also derived from first principles. Comparison is made between the new model and currently available models. © 1990 American Institute of Physics.