Design of Asymmetric Supersonic Propulsion Nozzles: A Computational Analysis

Abstract

Air-breathing hypersonic systems require better integration of their constituting elements in order to achieve higher thrust-minus-drag capabilities. Asymmetric supersonic nozzles are pivotal parts of these systems. On the basis of axisymmetric flow-field calculations, a technique for designing complex arbitrary cross-section nozzles is provided. The method of characteristics (MoC) is applied for the design of the original axisymmetric configuration profile having the required length and Mach number. The needed asymmetric profile is then defined at its exit cross-section and described by an adequate number of stations that define its geometry. They are therefore followed back to the throat, resulting in the required asymmetric configuration. Two asymmetric nozzles were created using this method, one with an elliptic cross-section and a corrugated one. The Ansys-Fluent environment was used to analyze the three-dimensional (3D) flow-fields within the asymmetric profiles, and the k-ω SST turbulence model was applied to close the system required to offset the effect of the boundary layer. The numerical results obtained were compared to those gathered from an analogous elliptical nozzle. They were further compared to the results obtained on the original axisymmetric configuration from which the two asymmetric elliptic and corrugated profiles were generated earlier. The good agreement obtained between the diverse components of the study provides much credence to the method developed, proving that it is possible to design satisfying asymmetric configurations.