Supersonic Nozzle Flow: Separation and Shock Wave

Supersonic Nozzle Flow Separation and Shock Wave — ANSYS Fluent CFD Simulation

Description

Welcome to the Supersonic Nozzle Flow Separation and Shock Wave CFD Simulation module. This project explores supersonic nozzle flow using ANSYS Fluent, focusing on the intricate phenomena of flow separation and shock-wave formation. A supersonic nozzle accelerates gas from subsonic to supersonic speeds through a converging-diverging passage, but under off-design conditions the flow can separate from the walls and form shock waves — sharp discontinuities across which pressure, temperature, and Mach number change abruptly. Capturing these effects is central to the design of rocket engines, supersonic wind tunnels, and high-speed propulsion systems. Within the Compressible Flow: Beginner CFD Training Package, this project builds on the convergent-divergent nozzle case by focusing on the shock waves and boundary-layer separation that dominate supersonic nozzle behavior.

Methodology

The setup is built around the governing equations of compressible flow in the supersonic regime, with a turbulence model chosen to suit high-speed flow and its shock-turbulence interactions. The simulation captures the transition from subsonic to supersonic flow through the converging-diverging passage, resolving both normal shock waves and the oblique shock structures that form in an overexpanded nozzle and interact with the walls. The boundary-layer development is modeled to reveal where the flow separates under the adverse pressure gradient, and the setup supports varying the back pressure to study how the nozzle flow adapts across overexpanded and underexpanded regimes.

Analysis

The results provide Mach number contours that reveal the flow acceleration and shock formation along the nozzle, together with the pressure and temperature jumps across the shocks — the pressure discontinuities and the temperature rise from shock compression that matter for material selection and thermal management. From these you can identify the separation point under different pressure ratios, quantify nozzle performance through the thrust coefficient and efficiency, and visualize complex shock structures such as shock diamonds. By the end of this project, you'll be able to set up a supersonic nozzle simulation with a compressible solver, capture normal and oblique shock waves and boundary-layer separation, study the effect of back pressure on the flow, and interpret the Mach, pressure, and temperature fields that govern rocket-nozzle and high-speed propulsion design.