Coding and velocity profile analysis of an elliptical exhaust nozzle

The thrust of an aircraft or rocket engine is largely dependent upon the momentum imparted to the products of combustion by discharging them through an exhaust nozzle. The design of an exhaust nozzle has special importance in determining the thrust and performance of an aircraft / rocket. In recent years, the design of the exhaust nozzle has received considerable attention as it directly impacts the overall performance. The aim of this paper is to study the behavior of a velocity field at the exit cross section of an elliptical nozzle. In this regard, an algorithm has been developed using the governing equations to compute the velocity at the exit of an elliptic exhaust nozzle for various aspect ratios and widths. The algorithm also provides the maximum Mach number at the exit. Subsequently plotting of Mach number contours for a range of aspect ratios is carried out. Flow is assumed to be moving under the influence of a pressure gradient. The analysis of velocity profile at exit plane of an elliptical nozzle in subsonic, supersonic and hypersonic regime is carried out which provides an understanding of the behavior of flow with variation in aspect ratio or width of an elliptical exhaust nozzle. The velocity profile obtained from algorithm for different aspect ratio and width is then compared to find the optimal design. The criteria for the optimal design of an elliptical exhaust nozzle is delivering the maximum exhaust velocity and thus thrust which is of prime importance in the design of an aircraft exhaust nozzle. This exhaust velocity, leading to thrust, is dependent mainly on the configuration of the nozzle walls i.e. geometry of the exhaust nozzle. In future, experimental validation of these results is suggested using the wind tunnel and also through computational techniques. The same approach can be used to study exhaust nozzles of varying cross sections for example triangular, square, rectangular, circular etc. The study will help in the development of optimized aircraft exhaust nozzles for future advanced aircraft.