Nozzle Flow Classification

Nozzle Flow Classification

April 2026
MATLAB Compressible Aerodynamics Flow Classification Numerical Methods Data Visualization

Objective

The goal of this project was to analyze flow in a converging-diverging nozzle under different flow conditions in order to identify key elements of nozzle flow, such as exit velocity, as well as shock location and angle wherever possible.

Methodology

A MATLAB program was developed to classify flow within a converging-diverging nozzle based on the specified back pressure ratio. The implementation applied compressible flow relations to determine the operating regime and calculate key flow properties, including exit conditions and the location of normal shocks when present. The results were then compared against theoretical nozzle behavior to verify the accuracy of the classification algorithm.

Results

The developed MATLAB program successfully classified all seven operating conditions for the converging-diverging nozzle by varying the back pressure ratio. Representative outputs for each operating regime are shown below.

Case 1. Not Choked Flow
Case 1
Case 2. Choked at the Throat
Case 2
Case 3. Normal Shock in the Diverging Section
Case 3
Case 4. Normal Shock at the Exit Plane
Case 4
Case 5. Overexpanded Flow
Case 5
Case 6. Perfectly Expanded Flow
Case 6
Case 7. Underexpanded Flow
Case 7

Key Takeaways

  • Implemented a MATLAB tool to classify converging-diverging nozzle operating regimes.
  • Applied compressible flow theory to compute exit conditions and identify shock locations.
  • Verified predicted flow behavior against theoretical expectations for seven representative pressure ratios.
  • Strengthened understanding of compressible flow and numerical implementation techniques.