燃油温度对正庚烷喷雾和着火特性的影响

A constant volume combustion chamber model was built on the computational fluid dynamics software Converge, and n-heptane was used as the surrogate fuel. At two ambient temperatures of 775 K and 850 K, the impact of fuel temperature dropping from 353 K to 233 K on spray and ignition characteristics was studied. The results show that, with the dropping of fuel temperature, the vapor penetration length of the spray keeps nearly the same, and the liquid penetration length increases by up to 16%. When the spray is quasi-steady, the evaporation ratio of higher fuel temperature increases, and the number of remaining parcels decreases but their sizes increase by up to 24%. The peak value of the mixture concentration along the nozzle axis rises by up to 16%. The ignition delay decreases nearly linearly with the increase of fuel temperature. The start time of low temperature reaction of n-heptane changes little as the fuel temperature rises, but its speed increases, and the formation of high temperature reaction production OH is earlier, as well as the higher combustion efficiency. Fuel temperature has two methods to affect ignition delay at different ambient temperatures. At the ambient temperature of 850 K, the dropping of fuel temperature increases the ignition delay mainly by decreasing the local concentration and temperature of the mixture, and the ignition delay can rise by 0.14 ms. At the ambient temperature of 775 K, the dropping of fuel temperature increases the ignition delay mainly by slowing down the process of chemical reaction before ignition, and the ignition delay can rise by 0.49 ms.