NUMERICAL ANALYSIS AND VISUALIZATION OF SHOCK STRUCTURES IN A CONVERGENT-DIVERGENT NOZZLE

Abstract

High-speed gas flow through Convergent-Divergent Nozzles is a fundamental aspect of aerospace and propulsion engineering, where efficient energy conversion is critical. This study presents a detailed numerical investigation of shock structure formation and flow behaviour within a Convergent-Divergent nozzle. Although the nozzle is initially designed for a Mach number of 2.0, the analysis reveals that the exit Mach number varies significantly with nozzle pressure ratio, ranging from approximately 2.1 under over-expanded conditions (NPR ≈ 6.81) to about 2.7 under under-expanded conditions (NPR ≈ 12.25) based on boundary conditions. A Computational Fluid Dynamics approach is employed using a density-based implicit solver to simulate compressible flow across different regimes, including choked, over-expanded and under-expanded conditions. The study evaluates variations in key flow parameters such as Mach number, static pressure, temperature, and velocity, highlighting their dependence on NPR and nozzle geometry. The results provide detailed visualization of shock structures and their propagation within and downstream of the nozzle. It is observed that both the location and intensity of shock waves are strongly influenced by NPR. The findings are consistent with compressible flow theory and contribute to a better understanding of shock dynamics, offering valuable insights for optimizing nozzle design and improving performance in high-speed propulsion systems.