Evaluation of Injection Strategies in Supersonic Nozzle Flow

Bernhard Semlitsch,Mihai Mihăescu

doi:10.3390/aerospace8120369

Abstract

The ability to manipulate shock patterns in a supersonic nozzle flow with fluidic injection is investigated numerically using Large Eddy Simulations. Various injector configurations in the proximity of the nozzle throat are screened for numerous injection pressures. We demonstrate that fluidic injection can split the original, single shock pattern into two weaker shock patterns. For intermediate injection pressures, a permanent shock structure in the exhaust can be avoided. The nozzle flow can be manipulated beneficially to increase thrust or match the static pressure at the discharge. The shock pattern evolution of injected stream is described over various pressure ratios. We find that the penetration depth into the supersonic crossflow is deeper with subsonic injection. The tight arrangement of the injectors can provoke additional counter-rotating vortex pairs in between the injection.

Highlights

A wide range of engineering applications capitalises on the benefits of fluidic injection into supersonic crossflows, e.g., flame-holding [1], thrust vectoring [2], supersonic airbreathing engines, and noise suppression [3,4]
We shade light into the effects of fluidic injection into a supersonic convergent–divergent nozzle flow using the Large Eddy Simulations (LES) approach, where we focus on a beneficial location identified by Semlitsch & Mihăescu [16]
We define the shock pattern occurring without injection as the baseline, where an oblique shock anchors slightly downstream of the nozzle throat and merges in the core in the form of a Mach-disk

Summary

Introduction

A wide range of engineering applications capitalises on the benefits of fluidic injection into supersonic crossflows, e.g., flame-holding [1], thrust vectoring [2], supersonic airbreathing engines, and noise suppression [3,4]. Semlitsch & Mihăescu [16] applied multiple injection into nozzle crossflows to manipulate the shock pattern of supersonic exhausts using steady-state RANS simulations. The understanding of the mutual influence of injected streams is limited especially in supersonic flow regimes where flow and shock structures interact. With this investigation, we shade light into the effects of fluidic injection into a supersonic convergent–divergent nozzle flow using the LES approach, where we focus on a beneficial location identified by Semlitsch & Mihăescu [16]

Methods

Results

Conclusion