Detemination of a heat transfer between injected diesel fuel and a temperature controlled wall

The paper presents results of the experimental determination of heat fluxes between diesel fuel jet and a steel wall. The experiments were performed in the high pressure and temperature rig at the Chalmers University. The experimental stand allowed setting the pressures and the temperatures in the chamber similar to the conditions in a diesel engine during the compression stroke. A standard common rail injecting system and an injector with a single hole nozzle were used. The measurements were taken for different pressures/temperature combinations. However, in respect to have similar jet formation conditions and fuel droplets penetration range, the air density in the chamber was kept on constant level. The temperature-controlled wall was mounted perpendicular to the fuel jet. The wall was equipped with coaxial thermocouples for recording the surface temperatures. The thermocouples had very thin vacuum deposited junctions that offered very fast response. The recorded time histories of the surface temperatures were used to calculate the local heat fluxes on a basis of the one-dimensional transient heat conduction model. The experimental chamber had an optical access allowing observing the jet and the swirl formation when the fuel reached the wall. A high-speed camera was used to record the jet behaviour.