Experimental and numerical study on mixture concentration distribution and ignition characteristics of biodiesel/n-butanol dual-fuel spray impingement in inert and combustion environments

Dual-fuel spray impingement is an important means to realize the reactivity and concentration stratification in dual direct injection engines. In the present study, the dual-fuel (biodiesel and n-butanol) spray impingement in inert and combustion environments was experimentally and numerically investigated. The mixture concentration distribution and ignition characteristics were analyzed. The results show that as the biodiesel and n-butanol sprays impinge with each other, the overall equivalence ratio reaches maximum value around the initial impingement region and decreases outwardly, forming the concentration and reactivity stratification. Biodiesel has a slower evaporation rate but a faster reaction rate than n-butanol. As the impingement angle increases, the spray area after the collision decreases, and the low-temperature region and high-equivalence ratio region are more concentrated, reducing the spray evaporation and temperature distribution. Conversely, increasing the injection pressure can enhance the mixing between spray and ambient gas and increase the temperature distribution.