Fluid-structure interaction characteristics of inflatable reentry aeroshell at subsonic speed

Abstract

Inflatable aeroshells, made of flexible membranes and pressurized inflatable torus, experience significant aerodynamic loads during atmospheric entry. The aerodynamic forces deform the lightweight, flexible membrane, and such deformation changes the flow field, changing the aerodynamic characteristics and increasing the deformation even further. Thus, fluid-structure coupled modeling of these problems is crucial for the reliable performance prediction of such reentry vehicles. This study provides wind tunnel experimental results on subsonic fluid-structure interaction (FSI), focusing on the aeroshell deformation and oscillatory behavior designed to validate coupled simulations. Wind tunnel experiments were conducted using a scaled membrane aeroshell model for subsonic speed. Aerodynamic coefficients, pressures at the rear of the model, and structural vibrations were measured for freestream Mach number of 0.3. A two-way coupled FSI model was set up in a partitioned manner for analyzing detailed distributions of the flow field properties, which was validated by the experimental data. The model was based on the open-source fluid solver OpenFOAM, computational structural solver CalculiX and coupling library preCICE. The present FSI analysis model well reproduced fundamental features such as swing motion, membrane deformation, and the wake in the flow field simulation, which were observed in the experiment. The results indicated that the membrane surface deforms elastically by aerodynamic force caused by the large pressure difference between the front and rear sides of the vehicle. The continuous generation and shedding of the wake vortex caused unsteady behavior in the flow field, followed by the small amplitude oscillation of the aeroshell. An external aerodynamic force caused the oscillation because the frequency of this oscillation did not correspond to that of natural frequencies.