Experimental analysis of the pressure–velocity correlations of external unsteady flow over rocket launchers

Abstract

Based on simultaneous wall pressure and velocity measurements, the aerodynamic load of a launcher body model is investigated. Two different configurations are considered in order to study the influence of geometrical artifacts on the after-body flow and consequently on the aerodynamic load. After a brief presentation of the experimental setup used to get the unsteady wall pressure and external velocity field, a global analysis of the integrated pressure along the nozzle is presented for both configurations. It is shown that the unsteady load induced on a configuration with attachment device involves characteristic frequencies which fits the mechanical response of the structure whereas no particular behavior is observed on the configuration without attachment device. Then, a Proper Orthogonal Decomposition (POD) is successively performed from the wall pressure field and from the external velocity field highlighting the relationship between the most energetic structures of the flow and the involved phenomenon. Finally, a pressure–velocity correlation of the POD modes is presented and the most energetic structures of the velocity field are linked to the unsteady load observed on the nozzle. It is then confirmed the structural influence of the attachment device and its contribution to the unsteady loads acting on the nozzle.