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A zero-dimensional computation model for the heat release rate of a swirl chamber diesel engine is established in this paper. With the aid of control volume analysis method of variable mass thermodynamic system, the instantaneous discharge coefficent of the connecting passage of combustion chambers is accurately determined by calculating the motored indicator diagrams of main and swirl chambers. A deeper study is also made on the heat release rate and other combustion characteristics under various conditions of the swirl chamber diesel engine such as connecting passages with different structural parameters, different shapes of main combustion chambers and different operating conditions. Thus some beneficial conclusions are reached, that is, the combustion delay in the main combustion chamber of the swirl chamber diesel engine is an important reason for its fuel economy lower than that of a DI diesel engine besides its greater losses of flow and heat.

This paper presents the results of experimental studies carried out on a spark-assisted, direct-injection, diesel engine operating on methanol, ethanol and gasoline (all having low cetane numbers) as well as on diesel fuel. The key measures that ensure reliable ignition and stable flame propagation through the inhomogeneous mixture are the character and location of the fuel spray in the combustion chamber relative to the location of the spark in both the vertical and horizontal directions, the spark plug gap, and the timing of injection and spark. When these parameters are optimized, the engine runs smoothly over a wide range of speeds and loads. The ignition characteristics, rates of heat release, cycle-to-cycle variations, NOx emissions, and thermal efficiencies of the engine operating on these four fuels are analyzed and compared in detail.

Compared with bathtub combustion chamber which is widely used in SI engines especially in China, this paper introduces an experimental investigation on the performances of SI test engine with a new squish jet-turbulence combustion chamber. The new chamber can combine inlet swirl and squish effectively. Results show that the engine with the new chamber gives better comprehensive performances. The combustion process shortens, and the lean burn limit extends.