Thermal boundary layer measurements using a multiple thin wire resistance thermometer in an internal combustion engine

Abstract

ABSTRACT A stand alone probe and a data acquisition system was designed and manufactured for collecting experimental data on the thermal boundary layer of the gases over the surface, as well as the local surface temperature of the cylinder head of a reciprocating internal combustion engine. The physical quantities to be measured were the instantaneous differential temperature of the inside and outside surfaces of the cylinder head, the gas temperatures at various distances from the surface and the gas pressure inside the combustion chamber, combustion chamber. 8 bit A/D converter, multiplexer, I/O interface and synchronization / interrupt / coder circuits were designed and manufactured. The resistance wire measurements were only possible during motored engine operation. The compression ratio of the engine, the temperature of the induced air and the cylinder head temperature were varied during the tests without stopping the engine.