Effect of Flow Compressibility in Convergent-Divergent Nozzle

Abstract

Nozzles come in a range of shapes and sizes based on a purpose such as the De Laval nozzle also known as the converging-diverging nozzle. The convergent-divergent nozzle is commonly used in modern rocket engines that accelerate at high velocity till the supersonic region Ma>1. This paper aims to investigate numerically the effect of the area ratio of the convergent-divergent throat and the Mach number from the incompressible flow to compressible flow. The software that was used to simulate cases is ANSYS Computational Fluid Dynamics (CFD) code FLUENT. The area ratio throat (AR= 5mm, 6mm, 7mm, and 8mm) and Mach number (Ma = 0.2, 1.0 and 1.8) were varied to obtain a more specific result. The result from this paper has shown that the most effective Mach number and area ratio are at 0.2 Ma with the AR=5mm According to the findings of this research, the most effective Mach number and area ratio is at 0.2 Ma with AR=5mm. According to the calculations performed in this research, the percentage variation of velocity at 0.2Ma was larger than at 1.0 Ma and 1.8 Ma. This happens cause in the sonic and supersonic flow there is a factor that disturbs the flow such as back pressure and normal shock.