Flow and acoustic investigations into the impingement of single and multiple jets onto a jet blast deflector

Abstract

Current space launch vehicles, employ a combination of Solid Rocket Boosters and Liquid Rocket Engines to provide the thrust required during the first stage of lift-off. Such combinations lead to the deployment of a multitude of jets, whose interactions with the Jet Blast Deflector(JBD) can have a significant bearing on the overall acoustic loading experienced by the vehicle. Flow and acoustic fields of multiple jets impinging on a jet blast deflector has not been adequately explored in the past. The present work investigates the flow and acoustic characteristics of four identical jets impinging on a generic JBD and compares them against the results for a single equivalent jet impingement. All the jets studied, issue from conical C-D nozzles with design Mach number of 2.0. The combined mass flow from the multiple jets was equal to that of the single jet. The flow field characterization was carried out using schlieren and the acoustic field was studied using microphone measurements inside an anechoic chamber. Two different arrangements of the multiple jets were studied to understand their interactions with the JBD and their influence on the flow and acoustic field generated.