Study on Unsteady Numerical Analysis of Plume Duct Flow Caused by Lifting-up Rocket

Abstract

A study to establish a prediction method for acoustic environment during rocket launch has been conducted using a multidisciplinary analysis method of fluid, acoustics, and structure in JAXA. This coupling method consists of following elements: numerical analyses of sound generation, sound propagation, sound transmission to fairing, and sound vibration of a payload. In this paper, a study of sound propagation analysis is reported. Using an Euler flow solver, the following two cases are compared; one is that a lifting-up rocket is modeled quasi-steadily according to rocket ascent, and the other is that a rocket is fixed above a modeled launch pad. The results of these calculations indicate that characteristic frequencies of sound wave observed at a point on flight path are different from each other and that one of the low frequency characteristics of observed sound wave at the observer point is caused by the inner acoustic resonance of a rocket plume duct.