Experimental and numerical investigation on pressure characteristics of the dual-valve controlled fuel system for low-speed diesel engines

Abstract

In order to analyze the pressure performance of a dual-valve controlled fuel system, a test bench for low-speed diesel engine fuel system was used. The experimental results showed that the system pressure fluctuation is obvious. Then theoretical analysis was performed to verify the mechanism for the apparent pressure fluctuation. The results show that the excessive pressure peak is caused by the high rising rate of fuel pressure. The difference between the fuel pressure and injection pressure is mainly correlated to the pressure loss along high-pressure fuel tube. And the pressure surge after fuel injection is due to water-hammer effect. In order to improve system structure, an AMESim model that has been validated fully was used to develop response surface prediction models of injection pressure peak, steady injection pressure and fuel injection quantity. For the determination coefficient and adjusted determination coefficient for each prediction model are more than 0.98, the calculation results from the prediction models are reliable. Based on the prediction models and Non-dominated Sorting Genetic Algorithm II, a multi-objective optimization was carried out to reduce the injection pressure peak and increase the steady injection pressure while ensure the variation of fuel injection quantity is within 10% finally. After optimization, at the cost of fuel injection quantity loss of about only 7.07%, the injection pressure peak is decreased by about 22.27% and the steady injection pressure is increased by about 33.32%.