Experimental Method for Determination of Boundary Conditions of Heat Exchange in Parts of External Combustion Engines

Abstract

The paper presents the validation of the experimental method for the determination of boundary conditions of heat exchange in the combustion chamber of internal-combustion engines. It is shown that despite great opportunities for the modern numerical methods for determination of thermal state of engine parts and the integrated packages which are available on their basis, the accuracy of the received results of the thermal state of the engine parts forming the combustion chamber depends on the accuracy of the experimental determination of boundary conditions of heat exchange. Boundary conditions of heat exchange for the differential equation describing the process of a non-stationary heat emission from a reaction mass to sides of the parts forming the engine combustion chamber are the values of the instantaneous heat transfer coefficient from gas to sides of the combustion chamber parts, gas temperature in combustor chamber, the instantaneous surface temperature of parts of the combustion chamber and temperature gradient on a normal to a surface of parts. A method was developed for measuring of flame temperature in the chamber condition based on pyrometry of spectral ratio with special optical system with interference light filters for determination of heat rejection ratio from gas to sides of the parts forming the engine combustion chamber. The membranous thermocouple is developed and the study of thermocouple dynamic characteristic was undertaken for measurement of instantaneous surface temperature of surface of details and temperature gradient on a normal to a surface of parts. Amplifying and recording equipment is developed and experimental measurement of the basic parameters in the engine combustion chamber is permormed. The results confirm the efficiency of the proposed methods for the experimental determination of boundary conditions of heat exchange in internal combustion engines.