Underexpanded free and confined jet structures: CFD simulations

The study is focused on the flow characteristics of underexpanded jets with an increase of the total pressure. The simulations have been performed for a supersonic flow exhausted from an axisymmetric conic opening nozzle with nozzle pressure ratio (NPR) ranging from 2 to 7 using a commercial CFO Software. Numerical study reveals that the shock structure significantly depends on the geometry considered - free or confined exhausted flow. The comprehensive analysis shows that with the NPR increase, the both jets undergo Mach reflection forming the Mach disk in a different manner. The Mach disk height has been evaluated and compared for both geometries.