PREDICTIONS OF THE STRUCTURE OF TURBULENT, HIGHLY UNDEREXPANDED JETS

A mathematical model capable of predicting the shock and flow structur e of turbulent, underexpanded jets is described. The model is based on solutions of the fluid flow equations obtained using a second-order a ccurate, finite-volume integration scheme together with an adaptive gr id algorithm. Closure of these equations is achieved using a k-epsilon turbulence model coupled to the compressible dissipation rate correct ion proposed by Sarkar et al. (1991a). Extending earlier work which de monstrated the ability of this model to predict the structure of moder ately underexpanded jets, the present paper compares model predictions and experimental data, reported in the literature, on a number of hig hly underexpanded releases. The results obtained demonstrate that the model yields reliable predictions of shock structure in the near field , inviscid region of such jets, while in the far field results derived using the compressibility corrected turbulence model are adequate for predicting mean flow properties, and are superior to those obtained u sing a standard k-epsilon approach.