Experimental and numerical investigations on flow field characteristics of pintle injector

Abstract The objective of this study is to investigate the mechanism of mixing and atomization of pintle injectors numerically and experimentally using water and nitrogen. During the experiments, three cases with identical water injection condition and different nitrogen mass flow rate were performed. The nitrogen injection velocity was adjusted by changing the cross section of the exit gap. In other words, three cases with different gas/liquid momentum ratio and Weber number were analyzed. Meanwhile, simulations consistent with test conditions were conducted to compare with the experimental data. High-speed imaging was applied to capture of the movement of the flow field. In order to obtain the atomization cone angles, a series of image processing algorithms named principal component analysis (PCA) and region growing were adopted. Conclusions can be drawn that both the experimental and numerical results show a decrease tendency of atomization cone angle with the increase of gas/liquid momentum ratio. The PCA and region growing method was verified to be feasible and accurate for calculating atomization cone angle. The distribution characteristics of Sauter mean diameter (SMD) are determined together by Weber number and gas/liquid momentum ratio. Increasing the Weber number will help to reduce SMD and make its distribution more uniform. However, the SMD near the axis line is relatively large in the case of large momentum ratio.