Philip Hill

Given the problems of maintaining safely breathable air in cities, and the threat of global warming due to “greenhouse gas” emissions, increasingly strict regulations on engine emissions are to be expected. The diesel engine, though the most efficient engine ever to be widely used in transport, is a substantial contributor to ambient concentrations of particulates and oxides of nitrogen; it may not survive unless new technology is introduced. A promising way to make this engine more environmentally acceptable is to switch to natural gas fueling. To make use of natural gas with highest efficiency and acceptable emissions requires new understanding. Key research issues are: (1) how to enhance auto-ignition of the natural gas (which has high auto-ignition temperature), (2) how to inhibit formation of the oxides of nitrogen during the combustion process, (3) how to estimate kinetically limited and turbulence-limited combustion rates, (4) how to optimize the coupling between fluid motion and combustion.

Techniques that are available to us in this research include flow visualization (in an optical chamber in which we can see gas the jet injection), flame visualization (in an engine in which we can watch flame initiation and development), measurement combustion pressure rise and emissions (in single- and multi-cylinder engines), and numerical simulation of the entire injection-mixing-combustion-pollutant formation process. With the benefit of experimental information the numerical simulation is able to represent the main features of the process and should in time become capable of prediction for design and control optimization.

As this knowledge unfolds we are busy designing new high pressure gas injector prototypes to meet the stringent requirements of high efficiency and low emissions. Another high priority design task is focused on the need for an efficient variable-duty gas compression system. With our own facilities we are able closely to integrate research, design, and testing of laboratory prototypes for gas compression and injection in engine operation.

Selected Publications

• Ouellette, P., and Hill, P.G., “Turbulent Transient Gas Injections”, ASME Journal of Fluids Engineering, Vol. 122, pp. 743-753, December 2000.
• Hill, P.G., “Analysis of Combustion in Diesel Engines Fueled by Directly Injected Natural Gas”, ASME Journal of Engineering for Gas Turbines and Power”, Vol. 122, pp. 141-149, January 2000.
• Hill, P.G., “Transient Turbulent Gaseous Fuel Jets”, ASME Journal of Fluids Engineering”, Vol. 121, pp. 93-101, March 1999.
• Hill, P.G., “Relating Burning Rate and NO Formation to Pressure Development in Two-Stroke Diesel Engines”, ASME Journal of Energy Resources Technology, Vol. 119, pp. 129-136, June 1997.
• Hodgins, K.B., Ouellette, P., Hung, P., and Hill, P.G., “Directly Injected Natural Gas Fueling of Diesel Engines”, SAE Paper No. 961671, 1996.
• Mtui, P.L., and Hill, P.G., “Ignition Delay and Combustion Duration with Natural Gas Fueling of Diesel Engines”, SAE Paper No. 961933, 1996.
• Hill, P.G., and Zhang, D., “A Review of Swirling Flow and Combustion in Spark-Ignition Engines”, Progress in Energy and Combustion Science, Vol. 20, pp. 373-429, 1994.