On the selection of optimal values for the thermal contact of structural components of aircraft engines

Аuthors

Mesnyankin S. Y.

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

e-mail: heat@mai.ru

Abstract

This paper deals with the problems related to the determination of the temperature state of contacting elements of aircraft engines, when contact thermal resistance occurs due to the imperfections of the mechanical coupling due to the discrete nature of the contact. It also considers physical aspects of the contact heat exchange and analyzes three components of thermal energy transfer.

The known analytical equations describing contacting in the air were analyzed in detail. The conclusion was drawn that the known dependences cannot be universal for practical problems, though the difference between the calculated values and the experimental data due to the uncertainty of numerous empirical coefficients and conditions of generalizing dependencies is essential. This statement is supported by the calculations with respect to the contact pair of stainless steel in a wide range of thermal and mechanical stress, which further allowed us to estimate additionally the contribution of different components of point contacts thermal resistance and environment.

Taking into consideration the revealed discrepancies and for the purpose of a more rigorous recordkeeping of temperature losses in the contact zone, the author suggests a fundamentally new generalized equation, which derivation is based on the classic analysis of the contact conductance components.

Describing successively the share of each value of the total thermal resistance in dimensionless form and justifying the influence of each of the values the author proposed the structural formula. The empirical coefficients of this formula are obtained by statistical processing of the well-known experiments. The results of summarizing are shown in the form of a graphic dependence of the contacting materials and their surface finishing.

According to the results of generalization a conclusion about a successful correlation of experimental and calculated data is made. The reasons of the marked differences are analyzed as well.

The results of the work with great certainty and precision allow us to determine the values of the thermal contact resistance between materials of special interest and to select their optimal values.

Keywords:

thermal contact, contact thermal resistance, analysis of calculated dependencies, generalized dependence, comparison with experiment

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