SIMULATION OF BACK PRESSURE EFFECT ON BEHAVIOUR OF CONVERGENT DIVERGENT NOZZLE

Abstract

ABSTRACT:- In this research a simulation of steady flow of a gas through a convergentdivergent nozzle which has a varying cross sectional area will be considered. The nature ofthe flow can be explained by considering how the flow and its characteristics in the nozzlechanges as nthe back pressure Pb is decreased.The characteristics of gas flow i.e.(Mach number, static pressure, density, velocitymagnitude and static temperature) distributions for the convergent divergent nozzle areimplemented by using the ANSYS Fluent 12.1 software to solve the quasi-one dimensionalnozzle flow.The reductions in the back pressure cannot affect conditions upstream of the throat. Thenozzle is, therefore, choked. The shock wave increases the pressure, density and temperatureand reduces the velocity and Mach number to a subsonic value, and as back pressure isfurther reduced to a certain value, the extent of the supersonic flow region increases, theshock wave moving further down the divergent portion of the nozzle towards the exit plane.