Performance Prediction of Conical Nozzle Using Navier–Stokes Computation

Abstract

This paper describes the numerical investigation of convergent conical nozzles done in the AIAA Propulsion Aerodynamic Workshop number one. Axisymmetric, three-dimensional, and unsteady computations were conducted for three main test cases. These test cases were 1) axisymmetric convergent conical nozzles of 15, 25, and 40 deg half-angle as well as a reference nozzle; 2) the 25 deg half-angle nozzle with a splitter plate inserted in its plane of symmetry; and 3) the vortex shedding observed at the base of the splitter plate. The effects of base drag and freestream Mach number on calculated velocity coefficient were analyzed. The discharge coefficients and velocity coefficients determined from the axisymmetric solutions matched the experimental data well. The wall Mach numbers and sonic line positions were also well predicted. In the axisymmetric computations, the shock position was well captured by the fine grid. However, when the nozzle pressure ratio was high, the three-dimensional Reynolds-averaged Navier–Stokes results may have been less reliable. Three-dimensional results with the splitter plate in the nozzle show that the shock wave location is changed by the presence of the splitter plate. The unsteady zonal shear stress transport-detached eddy simulation method was used to simulate the vortex shedding at the base of the splitter plate. The primary shedding frequency of 32.2 KHz was obtained by analyzing the viscous force at the splitter trailing edge.