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Laws concerning emissions from heavy duty (HD) internal combustion engines are becoming increasingly stringent. New engine technologies are needed to satisfy these new requirements and to reduce fossil fuel dependency. One way to achieve both objectives can be to partially replace fossil fuels with alternatives that are sustainable with respect to emissions of greenhouse gases, particulates and nitrogen oxides (NOx). A suitable candidate is methanol. The aim of the study presented here was to investigate the possible advantages of combusting methanol in a heavy duty Diesel engine. Those are, among others, lower particulate emissions and thereby bypassing the NOx-soot trade-off. Because of methanol’s poor auto-ignition properties, Diesel was used as an igniting sources and both fuels were separately direct injected. Therefore, two separate standard common rail Diesel injection systems were used together with a newly designed cylinder head and adapted injection nozzles.

It is generally accepted that knocking combustion influences the heat transfer in SI engines. However, the effects of heat transfer on the onset of knock is still not clear due to lack of experimental data of the thermal boundary layer close to the combustion chamber wall. This paper presents measurements of the temperature in the thermal boundary layer under knocking and non-knocking conditions. The temperature was measured using dual-broadband rotational Coherent anti-Stokes Raman Spectroscopy (CARS). Simultaneous time-resolved measurements of the cylinder pressure, at three different locations, and the heat flux to the wall were carried out. Optical access to the region near the combustion chamber wall was achieved by using a horseshoe-shaped combustion chamber with windows installed in the rectangular part of the chamber. This arrangement made CARS temperature measurements close to the wall possible and results are presented in the range 0.1-5 mm from the wall.

Two experimental techniques, Particle Image Velocimetry (PIV) using a water-analogy Dynamic Flow Visualisation Rig (DFVR) and Laser Doppler Anemometry (LDA) in a motored research engine, were used to investigate the flow pattern generated within the combustion chamber of a gasoline direct injection (G-DI) engine. The in-cylinder flow was also modelled for the two cases using the Computational Fluid Dynamics (CFD) code VECTIS; that is, models were created using first water and then air as the working fluid. The experimental and computational results were converted into the same format and hence compared qualitatively and quantitatively. All results showed good agreement and were used to validate the different techniques. The correlation between the CFD air simulation results and the LDA results demonstrates that the CFD code can be used to predict reliably the air motion created in the combustion chamber of a G-DI engine.