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Visualization of Mechanical Processes: An International Online Journal


ISSN Online: 2152-209X

Visualization of Mechanical Processes: An International Online Journal

DOI: 10.1615/VisMechProc.v1.i3.100

VISUALIZATION OF ABLATION AND SPALLATION OF ICY OBJECT IN HYPERSONIC FLOW AT MACH NUMBER 7

Kojiro Suzuki
Japan Society for Aeronautical and Space Sciences
Osamu Imamura
Department of Sustainable Engineering, College of Industrial Technology, Nihon University, 1-2-1 Izumi-cho, Narashino, Chiba 275-8575, Japan
Takeo Okunuki
Department of Aeronautics and Astronautics, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan

ABSTRACT

To investigate the aerothermodynamic phenomena around an icy meteorite entering the atmosphere, a series of experiments have been conducted by putting a spherical ice piece in the test section of the hypersonic wind tunnel in Kashiwa campus, the University of Tokyo. The ablation, spallation, and fragmentation of an icy object are successfully simulated and observed in the Mach number 7 flow. The liquid water and the vapor produced under the severe aerodynamic heating in the stagnation region go downstream over the surface and are refrozen into icy columns in the shoulder region, forming a brimlike structure. The IR camera images clarify that the surface temperature of the icy body is kept around 273 K in the hypersonic flow due to the latent heat of the ablation. The high-speed movie reveals that small ice pieces are spalled at the tips of the icy columns. The fragmentation of the object is initiated by the removal of icy columns from the body. It is observed that a large amount of mist is injected from the surface just before the fragmentation. These results will become useful for the discussion on the survivability of the meteorite in the atmosphere and the possibility of the delivery of the extraterrestrial material into the atmosphere during its entry flight.