Modeling and analysis of velocity profile of a rectangular aircraft exhaust nozzle

This research is aimed to investigate the flow behavior at the exit plane of a rectangular aircraft exhaust nozzle for different aspect ratios. An algorithm has been developed to evaluate the velocity profile at the exit cross section of a rectangular aircraft exhaust nozzle. The same algorithm has also been used to calculate the velocity field and plot the velocity contours for that cross section. This algorithm has been run for four different aspect ratios. Each aspect ratio has been investigated for three flow regimes i.e. subsonic, supersonic and hypersonic. After running the algorithm for all twelve cases, the results have been compared for finding the optimal aspect ratio for a specific flow regime which offers the maximum flexibility for design of exhaust nozzle. Criteria for the optimal aspect ratio has been based on the maximum exhaust velocity as maximum exit speeds are of prime importance in an engine exhaust nozzle design for thrust maximization. This study would serve as a benchmark for aircraft exhaust nozzle designers and scientists for the future investigation of the impact of varying aspect ratio on exit velocities for rectangular exhaust nozzles. In future, the same analysis may be validated experimentally using the wind tunnel as well as computationally. The proposed methodology may be followed to study other non-circular exhaust nozzles such as elliptic, triangular, rounded rectangle etc. This will give an insight into the behavior of flow when geometric characteristics of the exhaust nozzle are varied. Further it will help to optimize the design of exhaust nozzles as advanced manufacturing technologies have enabled us to manufacture difficult contours without compromising the strength of components.