ID 172

Simulations on the performance of shedding bubble clouds in cavitating jets and corresponding primary atomization

 

Abstract:

In order to make a further study on the cavitation flow and its effects on primary breakup progress, LES simulation coupled with VOF method was conducted to investigate the influence of shedding cavitation bubbles on jet breakup and atomization near the nozzle outlet. Detailed analysis has been made on the initial state of cavitating jet development progress ejected from a circle nozzle, and the shedding bubble clouds flowing inside the liquid jet were captured successfully. Simulation results illustrate that shedding clouds play an important role in surface wave formation and jet atomization. The increasing in amplitude of surface wave leads to the initial breakup off of the liquid ligament and droplets from the liquid domain. Besides, the breakups of another three noncircular cavitating jets with different eccentricities generated by asymmetric diesel nozzle were performed, and corresponding micro spray characteristics were analyzed near the nozzle outlet. The bottom semi-angle of elliptic jet was reduced significant as eccentricity increasing, but it has little influence on the upper semi-angle of spray. The eccentricity of initial jet was found having negative effects on liquid jet atomization. Both the profile spray angle in horizon and vertical plane decreased and the liquid core length grow as the liquid jet changing from an orifice one to an elliptical one.