Multi‒scale numerical investigations on the atomization performance of liquid‒liquid pintle injector

Three‒dimensional atomization field of the radial annular slot type liquid‒liquid pintle injector under different total momentum ratio (TMR) is simulated based on the volume of fluid to discrete particle model (VOF to DPM) method and the octree adaptive mesh refinement (AMR). The typical spray morphology of the injector is obtained, the variation of spray angle, breakup length of liquid film, amplitude of disturbance waves before liquid film breaking and its causes are analyzed. The results show that the injector can form a hollow conical spray during operation, and there are two recirculation zones near the inner surface of liquid film. According to the characteristics of the spray morphology, the spray can be divided into four areas: undisturbed liquid film, disturbed liquid film, fluctuating breakup zone and small droplets accumulation zone. The simulated spray angle is close to the model proposed by Heister when TMR is smaller than 0.6 and is close to the model proposed by Boettcher when TMR exceeds 0.6, with the maximum relative error of 9.5%. TMR has little influence on the amplitude of disturbance waves before liquid film breaking, while the breakup length of liquid film increases at first and then decreases with the increase of TMR. The breakup length is relatively large when TMR is close to 1, within the range of 20∼22 mm, while it is relatively small when TMR is far away from 1, within the range of 12∼15mm.