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An existing multidimensional in-cylinder flow code, KIVA, was modified to conduct port-and-cylinder gas flow, fuel spray, and combustion calculations in a port-fuel-injection engine. The effect of a moving valve with a stem was modeled using a novel internal obstacle technique in which the valve was represented by a group of discrete computational particles. Previously developed spray and combustion models were used to simulate fuel injection and combustion processes for a solid-cone shaped, pressure-atomized spray with isooctane as the fuel. The spray model was further modified to handle interactions between the spray drops and the valve. The model was applied to a generic port-fuel-injection engine with variations in port orientation, spray cone angle, and valve configuration (without and with a 180-degree shroud).

Increasing the injection pressure in DISI engine is an efficient way to obtain finer droplets but it will also potentially cause spray impingement on the cylinder wall and piston. Consequently, the fuel film sticking on the wall can dramatically increase the soot emission of the engine especially in a cold start condition. On the other hand, ethanol is widely used as an alternative fuel in DI engine due to its sustainable nature and high octane number. In this study, the fuel film characteristics of single-plume ethanol impinging spray was investigated. The experiments were performed under ultra-low fuel/plate temperature to simulate the cold start condition in cold areas. A low temperature thermostatic bath combined with specially designed heat exchangers were used to achieve ultra-low temperature for both the impinging plate and the fuel. Laser induced fluorescence (LIF) technique was employed to measure the thickness of fuel film deposited on the impinging plate.