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Supersonic Flows

FLOW-3D has a powerful compressible flow capability across a variety of aerospace applications, including supersonic flows.

Supersonic (Mach 3.1) Flow through a Jet Engine with a Spike

CFD aerospace simulation of supersonic flow through a jet engine

Supersonic flow through a jet engine

In this example, the gas is air. The engine is about 5 meters long and 1.5 meters in diameter. The spike is designed to optimize the flow of air in the intake by moving forward and backward as the plane's speed and the upstream flow conditions change (similar to a Blackbird spy plane engine). Ideally, the spike should be positioned so that the primary shock wave originating at its nose impinges exactly on the leading edge of the intake nozzle.

The spike is not positioned optimally in the simulation, therefore, the shock wave is located inside the engine, about 20 cm from its leading edge. Multiple reflections of the primary shock inside the engine create secondary waves, as can be seen in the insert. Heat is added to the air near the downstream end of the spike to simulate the burning fuel.

Supersonic Pingpong Balls

   
Modeling the effects of supersonic pingpong balls. Images courtesy of Littler Diecast Corporation.

The simulation on the left shows the evolution of air pressure in the tube. The development of a shock wave behind the ping-pong ball is clearly visible. It is caused by the flow of the high-pressure air from the open end of the tube, around the ball and into the low pressure region behind it. Since the exit end of the tube is closed, the shock wave is reflected there creating a high pressure zone. Units are Pa.

The simulation on the right takes into account the Mach number in the flow behind the ping-pong ball, which is clearly supersonic.