Effect of divergence on the compressible flow patterns in off-design planar nozzles

In the present work, the objective is to determine the Mach number and static pressure flow field behavior for off-design planar nozzle geometries with divergent angles of 1.21° (model A1) and 10.85° (model B1). ANSYS-Fluent R16.2 code was employed, and the RANS model and SAS turbulence model were applied to simulate in 2D the viscous flow field for the nozzle pressure ratio range of NPR 2.49 to 8.91. For model A1, in the divergent, the shock train is present, and the lateral pressure loads show fluctuations; in the centerline, the velocity is in the range of Mach 0.849 to 1.405. For model B1, the shock train is not present in the divergent, and the lateral pressure loads show flow separation; in the centerline, it is in the range of Mach 0.849 to 1.991. The flow velocity at the exit of the A1 model nozzle reaches Mach 1.357, which is 52.2% lower with respect to the B1 model, which has Mach 2.066. However, for the supersonic jet in the region of the atmosphere, the A1 model reaches Mach 2.967, which is 14.9% higher than with respect to the B1 model, which has Mach 2.522.