Comparison of euler and navier-stokes solutions for nozzle flows with secondary injection

Flowfields resulting from the injection of a sonic gas jet into the divergent section of a two dimensional convergent-divergent supersonic nozzle are analyzed numerically. The unsteady mass averaged Navier-Stokes and the Euler equations are solved using the explicit timesplit finite volume scheme of MacCormack for this purpose. Effects of fine scale turbulence are simulated in the Navier-Stokes equations by the algebraic turbulence model of Baldwin and Lomax with a limiter imposed on the turbulent eddy viscosity. A switched Shumann filtering algorithm is adopted for shock capturing. A grid refinement study is included to determine the required mesh spacing. The effect of limiting the turbulent eddy viscosity is studied. Comparison of the computed results with the experimental data are made in terms of injection side wall static pressure distribution and secondary specific impulse. The Navier-Stokes model predicts both the experimentally observed flow structure and the pressure distribution near the slot whereas the Euler model fails to predict both of them. Surprisingly the gross system performance parameter namely, the secondary specific impulse has been predicted well by both the Euler and the Navier-Stokes models.