Verification of Convergent-Divergent Nozzle Designs in Propulsion Aerospace Applications

Abstract

The performance of convergent and divergent nozzles is critical in aerospace propulsion systems, where the efficient expansion of high-temperature, high-pressure gases directly impacts thrust generation. In this study, we investigate a series of nozzle geometries using numerical simulations in ANSYS Fluent, guided by classical compressible flow theory, initially developed by Ludwig Prandtl. The governing equations of conservation of mass, momentum, and energy are solved under steady-state conditions, with emphasis on shock formation, boundary-layer effects, and Mach number distributions across the nozzle throat and divergent section. Parametric analyses are conducted to evaluate the influence of nozzle contour, area ratio, and throat geometry on flow acceleration and thrust coefficient. The results demonstrate close agreement with theoretical predictions of isentropic compressible flow while also highlighting deviations due to viscous and three-dimensional effects. These findings provide design insights for optimizing nozzle performance across propulsion applications, from launch vehicles to high-speed air-breathing systems. We obtained absolute error differences of 2.05 percent, 6.03 percent, and 9.9 percent in the throat temperature measurements for the RL10B2, SSME-40k, and A-1 nozzles, respectively.