OH, soot and temperature distributions of wall-impinging diesel fuel spray under different wall temperatures 2019-01-2184

OH, soot and temperature distributions of wall-impinging diesel fuel spray were investigated in a high-temperature high-pressure constant volume combustion vessel. The ambient temperature (T_a) was set as 773 K, and the wall temperature (T_w) was set as 523 K, 673 K, 773 K, respectively. Three different injection pressures (P_i) of 60 MPa, 100 MPa, 160 MPa, and the ambient pressures (P_a) of 4 MPa were applied. The OH spatial distributions of wall-impinging spray were measured by the method of OH chemiluminescence imaging. Two-color pyrometry was applied to evaluate the spatial distributions of KL factor and flame temperature of wall-impinging spray. The results reveal that, OH chemiluminescence is observed in the region near the impingement point firstly. The regions of high OH chemiluminescence intensity and high KL factor appear in the location near the wall surface along the whole combustion process. As the wall temperature increases, the appearance time of the OH moves up, the intensity and area of OH chemiluminescence increase. Besides, KL factor and the average flame temperature, the soot formation and oxidation rates also increase when the wall temperature increases. As the injection pressure increases, the intensity of OH chemiluminescence decreases. It can be concluded that the change of the wall temperature affects the spatial distributions of OH, KL factor and flame temperature of wall-impinging spray.