Calculation of heat load of ablative polymer protective material taking into account the nonequilibrium kinetics of destruction

Аuthors

, , Netelev A. V.^*, Ramazanova D. R.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: netelev@mai.ru

Abstract

Ablative polymeric materials are widely used as elements of heat-shielding packages in modern rocket and space technology, in particular, descent vehicles designed to enter the atmosphere of planets. During the operation of such devices, the question of determining the thermal loading of the outer layer of thermal protection is acute. Direct measurement of the heat flux on the surface of the heat-shielding material in this case is not possible due to the high temperatures and the degradation process in the material. To solve this problem, sensors integrated in the thermal protection can be used, in which the measuring elements — thermocouples, are buried in the bulk of the material. The sensors themselves, in this case, are made of a material identical to the material of the external heat-protective layer. When choosing the installation depth of the measuring element in the sensor, it is important that during the destruction of the sensor material the measuring element does not fall into the destruction zone, because this may affect the accuracy of the measured data and lead to thermocouple bypass.
The presented article is devoted to the development of an algorithm for processing data from heat flow sensors installed in an external collapsing layer of a heat-protective package of a descent vehicle. The initial mathematical model of heat transfer in such a material contains the equation of nonequilibrium thermochemical kinetics of destruction. The mass destruction rate was calculated as a function of temperature and heating rate. The developed algorithm is based on solving the inverse heat transfer problem by the iterative regularization method. Testing of the developed algorithm was carried out according to an experiment carried out in the «Thermal Laboratory» of the MAI department 601 at the experimental stand TVS-2M.

Keywords:

ablative heat-shielding coatings, nonequilibrium destruction kinetics, inverse heat transfer problems, iterative regularization.

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12. https://www.netzsch.ru (assessed 05.03.2020)