Aerodynamic instability of flare-type membrane inflatable vehicle in suborbital reentry demonstration

Abstract

An inflatable membrane reentry vehicle has been developed as one of the innovative reentry technologies. A suborbital reentry demonstration using a sounding rocket was carried out in 2012. Contrary to the result of a preliminary study, the vehicle always had an angle of attack (AoA) during its reentry. In addition, the amplitude of AoA gradually increased as altitude decreased, and the vehicle rotated vertically under Mach number of 0.1 (M0.1). As a first step to clarify the cause of attitude instability and vertical rotation, the aerodynamic characteristics, that concern static stability, are numerically investigated. Numerical simulations were carried out for the cases of Mach 0.9 (M0.9), 0.6 (M0.6), 0.3 (M0.3), and 0.1 (M0.1) and pitching moment coefficients () were obtained. Analysis software "RG-FaSTAR" for M0.9, and "FrontFlow/red" for M0.6, M0.3 and M0.1, are used, respectively. Large eddy simulation (LES) was performed using the standard Smagorinsky model to resolve highly unsteady flow features. Because the slope of with respect to AoA was negative for all cases, it was found that the vehicle is statically stable. For M0.9, M0.6 and M0.3 cases, absolute values of were almost the same. On the other hand, for M0.1, had a particularly large value, because the surface pressure distribution on rear side of the vehicle was different from the other cases. This difference was attributed to the separation point on the lower torus moving backward and turbulence in wake being enhanced with a decrease in Mach number and an increase in the Reynolds number.

Aerodynamic instability of an inflatable aeroshell in suborbital re-entry

“…Despite SMAAC being statically stable at all speeds, as reported by Ohashi et al, 10 its attitude was unstable during the mission. This can be attributed to a dynamic instability mode in the attitude.…”

Thermal Aeroelastic Characteristics of Inflatable Reentry Vehicle Experiment (IRVE) in Hypersonic Flow

“…Traditional thermal-fluid-solid coupling problems are mainly about conventional elastomers such as airfoils and turbine blades, but it becomes more complicated for flexible inflatable structures. Due to the unique properties of flexible materials, the structural dynamics shows strong geometric and material nonlinear features, which bring difficulty to the coupling of structural dynamics, hypersonic flow, and thermal dynamics [11]. In the past research about the IRVE system, the thermal aeroelasticity was divided into the aeroheating and aeroelastic problems based on the premise that the characteristic time of the flow field is much smaller than heat transfer [12].…”