Thermal computational fluid dynamics analysis of a converging-diverging rocket nozzle at varying inlet temperatures using k-w Turbulence Model

Abstract

Rocket nozzles play a critical role in propulsion systems by converting thermal energy into kinetic energy to generate thrust. This study investigates the thermal and flow characteristics of a converging–diverging rocket nozzle using Computational Fluid Dynamics. The simulations were performed using the standard k-w turbulence model at four inlet temperatures of 300, 350, 400, and 500 K, while inlet pressure, inlet velocity, and outlet pressure were maintained constant. The energy equation was incorporated to account for the thermodynamic effects of compressible flow. A mesh-independence study based on the Grid Convergence Index was conducted to assess numerical accuracy, with estimated discretization errors below 0.5%. The effects of inlet temperature on exit velocity, pressure, temperature, Mach number, and wall shear stress were subsequently evaluated. The results show that increasing the inlet temperature significantly enhances flow acceleration through the nozzle. The exit velocity increased from 612.4 m/s at 300 K to 791.0 m/s at 500 K, while the exit Mach number increased from 2.62 to 2.84. Higher inlet temperatures also resulted in a greater temperature drop across the nozzle, indicating enhanced conversion of thermal energy into kinetic energy. The pressure and temperature distributions exhibited the expected expansion behavior associated with converging–diverging nozzle flow. The highest wall shear stress occurred near the nozzle throat, where strong velocity gradients developed under choked-flow conditions. Overall, the findings demonstrate that inlet temperature significantly influences the aerodynamic and thermal performance of converging–diverging rocket nozzles and should therefore be considered in nozzle performance and thermal-loading analyses.