Comparative analysis of flow patterns in planar and conical nozzles with narrow divergent angles

The flow pattern in supersonic nozzles applied to the aerospace area is recurrently studied, since the geometrical profiles of the internal walls have a significant effect on the development of the flow regime. In the present work, the objective is to perform a comparative analysis of the flow patterns in planar and conical nozzles with very narrow divergent angles, for half-angle a = 1°, 1.21° and 2°. The viscous flow field was simulated in 2D with the ANSYS-Fluent R16.2 code. The RANS model and the SAS turbulence model were used for the transient state flow conditions. For viscosity as a function of temperature, the Sutherland's law equation was used. Numerical results of the flow field were obtained for the NPR range 3.98 to 6.95. In the divergent the shock train is presented, being for the conical nozzle the one with the highest velocity fluctuation in the shock fronts. For the flow at the nozzle outlet, for pressure load NPR 6.95, the conical nozzle with a = 1° has an average Mach number velocity increase of 8.81% with respect to the planar nozzle; likewise, for a = 1.21° it has an increase of 9.73% and for a = 2° it has an increase of 12.88%, respectively.