ID 161

Experimental Investigation on the Effects of Nozzle Geometry on Spray Characteristics Combining with Internal Cavitation Patterns

 

Abstract:

The diesel nozzle orifice geometry has great impact on the internal cavitation flow and spray characteristics. For this investigation, three different conicity nozzles with the same outlet diameter were adopted. A detailed comparison of spray characteristics and internal cavitation flow were investigated under injection pressure of 120MPa by using spray visualization method (Shadowgraph) and a validated model. The results indicate that the increase of the nozzle conicity is helpful to improve the mass flow rate, discharge coefficient and the average velocity, while the vapor phase fraction and turbulence kinetic energy decrease. Meanwhile, the cavitation domain is consistent with the high turbulence kinetic energy zone. Moreover, the spray tip penetration of cylindrical nozzle is smaller than conicity nozzle, because the cavitation in the cylindrical nozzle can strengthen the spray unstability. Furthermore, the spray cone angle increases as the nozzle conicity decreases, and the spray cone angle for cylindrical geometry nozzle is wider than that of conical2 geometry nozzle by 37.5% at 0.55ms, because the cavitation inside the cylindrical nozzle leads to an increment of the turbulence kinetic energy and cavitation, which is conductive to enlarge the spray cone angle.