Survey of Ballute Technology for Aerocapture

The drag coefficient for inflatable reentry vehicles shows discrepancies between a wind tunnel experiment and a flight test in a transonic regime. These discrepancies exist in the drag decrease behavior in the transonic regime and local minimum values of drag above the sonic speed in a wind tunnel. Hence, the present paper focuses on uncovering the reasons and mechanisms behind the same and investigates transonic flow fields around a vehicle by using a transonic wind tunnel and the computational fluid dynamics (CFD) approach. Several test models with diameters ranging from 56 to 96 mm are used to quantitatively evaluate the effects of scale and a sting attached on the rear. Aerodynamic coefficients, pressures at the rear of the model, and density gradient distributions are measured for operation conditions of free-stream Mach numbers ranging between 0.8 and 1.3. In addition, detailed distributions of the flow field properties are clarified using the CFD method, which is validated by the experimental data. The results indicate that a sting behind the test models reduces the steep drag decrease at transonic speeds and that shock waves reflected on the test-section walls of the wind tunnel result in local minimum values at supersonic speeds.

mentioning

confidence: 99%

Drag Behavior of Inflatable Reentry Vehicle in Transonic Regime

Takahashi

Matsunaga

Oshima

et al. 2019

“…In general, the use of a deployable aeroshell allows the vehicle to be decelerated at a higher altitude compared with a conventional rigid reentry vehicle. This provides several advantages for the entry, descent, and landing (EDL) approach, such as a lower heat load from aerodynamic heating and reduction in radio-frequency blackout [1][2][3][4][5][6][7][8][9]. Recently, a reentry vehicle with an inflatable aeroshell has also been developed in the Membrane Aeroshell for Atmospheric-entry Capsule (MAAC) project, in cooperation with several universities and JAXA.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic Heating Around Flare-Type Membrane Inflatable Vehicle in Suborbital Reentry Demonstration Flight

Takahashi

Yamada

Abe

et al. 2015

A demonstration flight of an advanced reentry vehicle was carried out using a sounding rocket. The vehicle was equipped with a flexible (membrane) aeroshell deployed by an inflatable torus structure. Its most remarkable feature was the low ballistic coefficient that enables reduction in aerodynamic heating and deceleration at a high altitude. During the suborbital reentry, temperatures at several locations on a backside of the flexible aeroshell and inside the capsule were measured by means of embedded thermocouples. The aerodynamic heating behavior of the vehicle was investigated using the measured temperature history, in combination with a numerical prediction in which a flow-field simulation of the heating was conducted. In this flow-field simulation, both laminar flow and turbulent flow were assumed, and the deformation of the flexible aeroshell was considered. A thermal model of the capsule and membrane aeroshell was developed, and the heat flux profiles of the vehicle surface during aerodynamic heating were constructed based on the measured temperatures. The measured temperature data were found to be in reasonable agreement with the predicted data if the flow field near the capsule of the vehicle was assumed to be laminar, with a transition to turbulent flow near the membrane aeroshell.

“…This technology can provide several advantages, e.g., reduction in aerodynamic heating during atmospheric reentry [1][2][3][4][5][6][7][8][9]. For flare-type thin-membrane aeroshells, several studies of elemental technologies and demonstration flights have been performed as part of the Membrane Aeroshell for Atmospheric-entry Capsule (MAAC) project [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Aerodecelerator Performance of Flare-Type Membrane Inflatable Vehicle in Suborbital Reentry

Takahashi¹,

Ha²,

Oshima³

et al. 2017

A flight experiment of an inflatable reentry vehicle, equipped with a thin-membrane aeroshell deployed by an inflatable torus structure, was performed using a JAXA S-310-41 sounding rocket. The drag coefficient history was evaluated by analyzing the acceleration of the vehicle with atmospheric density and temperature using a global reference atmospheric model. The vehicle successfully demonstrated deceleration. During the reentry flight, the position, velocity, and acceleration of the vehicle were obtained by using the Global Positioning System. The experimental drag coefficient had an almost constant value of 1.5 in the supersonic region but decreased to 1.0 in the subsonic region. In the transonic region, a steep decrease of the drag coefficient was confirmed. To study the detailed aerodynamics for the reentry vehicle, flow-field simulations were conducted with computational fluid dynamics techniques. The aerodynamic force acting on the vehicle was investigated with the measured data throughout the supersonic and subsonic regions. In the flow-field simulation, the computed result for the drag coefficient shows reasonable agreement with the experimental one. In addition, a compressible effect in front of the vehicle was seen to appear in the supersonic region and a vortex ring at the rear of the vehicle was formed in the subsonic region.