Overview

Raphael Lardat and Alain Dervieux
INRIA, Sophia-Antipolis, France

Bruno Koobus
Department of Mathematics, Universit de Montpellier II, France

Eric Schall
IUT G nie Thermique et Energ tique, Universit de Pau, France

Charbel Farhat
Department of Aerospace Engineering Sciences, University of Colorado at Boulder, USA

1. Introduction

Anyone who has examined the movie of the starting of a rocket would note how violent is the transient interaction of hot gases rushing out from the engine divergent. These jets are of high pressure and therefore quickly accelerate to a high supersonic regime before reaching the end of the divergent. Loads induced by supersonic flows on aerodynamical surfaces can lead to transient effects sometimes with flutter phenomena. A well known example is the flutter of a flat panel when a fast enough supersonic flow is applied along it [ASH 62]. The panel instability problem can be simulated by 2D calculations relying on a classical Euler model for the fluid flow.

Some papers also show this kind of behavior for axisymmetric nozzles under the action of an axisymmetric flow [LEF 00], [LDV 00]. In that case, the excited mode is not one of the main modes of the nozzle structure. Indeed, for generic divergents the first main modes are not axisymmetric. The purpose of the present work is to consider non-axisymmetrical coupling between an inviscid flow and a simplified model of the divergent (or nozzle). Different flow configurations involving shock waves behind or inside the nozzle are considered, and the possible flutter phenomenon is investigated...