Flow Field and Acoustic Investigations of the Launch Vehicle Environment during Lift-off

Abstract

During the lift-off phase, a launch vehicle is exposed to severe acoustic loads which are detrimental to the vehicle structure as well as sensitive equipment onboard. Any effort to reduce these loads is beneficial, as it reduces the additional strengthening of the vehicle structure and consequently the weight of the vehicle itself. The design of the jet deflector and launch environment such as launch platform influences the noise levels significantly. Any modifications to them for achieving noise reduction is quite challenging as it should take into account, the factors other than acoustics, such heat transfer, ease of vehicle access etc. Existing literature dealing with simplified jet impingement do not replicate the launch scenario faithfully, ignoring contributions from the factors like launch platform geometry and cutouts in launch platform. Very little is known on the level of impact of these factors on the propagation of noise from the jet exhaust. The present study attempts to address this by investigating the influence of presence of a launch platform with cut-outs on the acoustic field and flow field around a generic launch vehicle exhausting on a realistic jet deflector. The measurements include flow field visualization using shadowgraphy and aeroacoustic measurements using microphones in the near and far-field.