Computational Simulation of an Altitude Adaptive Nozzle Concept

Abstract

A computational analysis of an annular converging-diverging (CD) and an altitude adaptive expansion-deflection (ED) nozzle is presented. Numerical results were generated using a 2D axisymmetric, pressure-coupled solver in conjunction with the Spalart-Allmaras turbulence closure model and second order spatial discretisation schemes. Results were recorded over a theoretical altitude range and compared to experimental static pressure readings and schlieren images. The correlation between numerical and experimental static pressure values was high for all cases. Comparison of schlieren imagery outlined the large variety of flow regions within the ED nozzle flow field. The interactions between these regions were highly sensitive to turbulence and reinforced that conventional inviscid analytical techniques are unable to accurately describe behaviour within the ED nozzle flow field. The results highlight the salient effect of viscous effects within the ED nozzle flow field and justify a continued approach utilising computational fluid dynamics to increase understanding of the ED nozzle concept.