An Analytical Approach to Modeling Supersonic Retropropulsion Flow Field Components

Abstract

The propulsive-aerodynamic interaction created by a vehicle employing supersonic retropropulsion results in a complex flow field where the bow shock forms in response to the effective obstruction created by the vehicle and the nozzle exhaust plumes. Wind tunnel and computational efforts provide high fidelity insight into these flow structures at the expense of a significant time investment for running simulations. Leveraging analytical techniques to model this flow field allows for more efficient exploration of the effects of supersonic retropropulsion and provides more information on expected interactions prior to utilizing higher fidelity approaches. This paper proposes a method for analytically determining plume structure and the resulting bow shock structure for single and three nozzle supersonic retropropulsion configurations. The single nozzle model is used to validate plume generation methods, and the three nozzle models are used to validate the full flow field structure, including both plumes and the bow shock. Computational simulations at zero angle of attack with a freestream Mach number of 2 show favorable correlation with the developed model.