Acoustic Characterization of Jet Interaction with Launch Structures During Lift-Off

Abstract

The structures that constitute the environment surrounding the launch vehicle affect the noise levels experienced by it during liftoff. Earlier studies modeled the launch scenario by incorporating a jet impinging on plate geometries, either flat or curved, ignoring contributions from the components of the launch structures such as the launch platform. Very little is known about the effect of the structures on the propagation of noise from the jet exhaust toward the vehicle. This renders any effort to modify them for noise reduction quite challenging. The present study attempts to address this concern by investigating the contribution of a principal launch structure component, namely, the launch platform, toward the acoustic and flowfield around a generic launch vehicle exhausting on a generic jet blast deflector. The measurements include flowfield visualizations and aeroacoustic measurements using microphones in the near and far field. The results indicate that the presence of the launch platform increased the noise levels experienced by the vehicle beyond certain . It is also observed that replacing the solid launch platform with a perforated one leads to lower levels of noise compared to the solid one but still higher than the case where launch platform is absent.