ДВА МЕХАНИЗМА АЭРОТЕРМОМЕХАНИЧЕСКОГО РАЗРУШЕНИЯ ПРИ ГИПЕРЗВУКОВЫХ СКОРОСТЯХ ОБТЕКАНИЯ В ВОЗДУХЕ

Abstract

The issues of protecting the Earth from the collision with space objects are considered. The effectiveness of various methods of crushing such space objects, to alleviate the detrimental effects of their falling onto the Earth, are analyzed. In the framework of the task, the problem of experimentally studying aerothermomechanical carryover at the initial stage of the acceleration of a model of a meteorite at hypersonic velocities in the conditions of intensive background radiation is solved. Based on x-ray pictures and photographs of a body moving through the Earth's atmosphere at hypersonic velocities, a qualitative picture of the aerothermomechanical carryover and the deceleration of steel balls and balls made of a composite wolfram-nickel-iron alloy is presented. The processes observed during the motion of the steel balls and the balls of the composite alloy are shown to differ in their character. Their motion under the effect of the heat flow (convective or radiation) is accompanied by intensive heating of the frontal surface of the objects, followed by its carryover, which results in the changes of its mass and outline. During the motion from the polar part of the frontal surface along the flow, the level of thermal loading decreases and, hence, the film cools down. Accordingly, the viscosity of the melt increases, the flow rate of the film decreases, and a burl is formed. The accumulating melt periodically drops from the body surface. In the process of deceleration the flows decrease, the carryover stops, after which the outline of the objects no longer changes, and the surface temperature drops. For the steel balls, the carryover results from melting through the outer layer and drop losing. The carryover mechanism in the balls of the wolfram-nickel-iron alloy is connected with the different melting temperatures of its components and results in the motion of the wolfram particles in the direction normal to the direction of the motion of the body.Keywords: aero-thermo-mechanical ablation, aeroballistic experiment, X-ray imaging.