Numerical analysis of the flow field in a planar nozzle for different divergent angles

Abstract

In the present work, the flow field is analysed for Mach number, pressure and temperature in 2D computational domains for a planar nozzle of symmetrical geometry as used in the experimental tests for cold (air) flow. The study has been considered for three mean angles of the divergent section: α = 9°, α = 11.01° and α = 13°, and for four pressure ratios: NPR = 2.412, NPR = 3.413, NPR = 5.423 and NPR = 8.78. For the numerical simulation of the turbulence in the presence of shock waves, the RANS model, the Sutherland equation and the Spalart-Allmaras turbulence model were used in the ANSYS-Fluent R16.2 code. The results obtained show fluctuations at the intersections of the internal shocks in the divergent, and the fluctuation decreases as the angle of the divergent increases. For NPR = 3.413, NPR = 5.423 and NPR = 8.78, the Mach number at the nozzle exit is the same, where for α = 11.01° Mach 2.00 was obtained, and based on this reference, for α = 13° there is an increase in velocity of 4.15% and for α = 9° a decrease in velocity of 3.78%. The lowest pressure and temperature drop occurs at the nozzle outlet for α = 13°.