PECULIARITIES OF TESTING TECHNIQUES OF LANDING SPACECRAFTTHERMAL PROTECTION AT THE HIGH ENTHALPY TEST BED

摘要

The methodological peculiarities of ground testing ofthermal protection of spacecraft being returned atsecond space velocity into the Earth atmosphere areconsidered. The tests were carried out at a highenthalpy electric arc device at the realization ofmaximal heat flows, which are defined by preliminarycalculations at the reentry trajectory of spacecraft andhave the values of 10 kW/cm2. It is necessary to realizesuch levels of the heat flows at the ground tests,because it allows to estimate with great confidencemaximum velocity of ablation of primary material ofthermal protection of returned spacecraft expected inthe real condition. However non-steady process andhigh velocity of ablation of thermal protectionmaterials at this conditions made it very difficult tocarry out measurements and require to develop specialmethodical approaches for maintenance of reliability ofreceived characteristics of destruction of materials.Results of measurements of parameters of highenthalpy flow at the variation of operating modes of thetest bed are submitted. Optimum form and size ofworking surface of a sample of a material for groundtests of thermal protection are investigated anddetermined. Tests were carried out using three thermalprotection materials having principally differentmechanisms of destruction in high temperature flow atthe condition of high enthalpy flow of arc device. Theresults of the tests are analyzed. Series of providedtests at high enthalpy electric arc device has allowed tocreate reliable technique of carrying out parallel tests ofmaterials for selection thermal protection of spacecraftreturned in the Earth atmosphere. Optimum conditionsfor application of different types of thermal protectionmaterials were recognized.