Experimental Study On Breakup And Atomization Characteristics Of Coaxial Swirling Liquid Jet

Liquid rocket engine has the advantages of high specific impulse, repeated started, working time can be arbitrarily set, repeated use, adjustable thrust and so on. In the development history of human space technology, liquid rocket engine has long occupied the main position. And the satellite and space detector which is using normal temperature, non toxic liquid propellant is now a hot research topic in many countries. As the key component of the engine, the liquid-liquid coaxial swirl nozzle and the coaxial swirling liquid jet play a decisive role on combustion efficiency and stability of the engine. So it is of great significance to carry out the research on the atomization process of the nozzle.In this paper, cold spray experiments were carried out on two types of the external and internal mixed coaxial swirl nozzle and the atomization experiment device which were designed and built. The effects of operating conditions and nozzle geometry parameter on the breakup and atomization characteristics of the coaxial swirling liquid jet were researched under simulated propellant using high speed photography and Malvern particle size analyzer. And as a supplement to experimental research, the influence of the operating conditions on the internal flow characteristics of the liquid/liquid coaxial swirl nozzle was studied when the inner and outer nozzle are injected alone by using the numerical simulation method. The results indicated that:1. The gas entrainment effect of the recirculation zone formed by the inner and outer swirling liquid jet is the main reason for the formation of the external mixed coaxial swirling liquid jet. The change of liquid film impact wave caused by different position of interaction point is the main reason for the change of the breakup characteristics.2. The breakup length, SMD and droplet size distribution of the external mixed coaxial swirling liquid jet are the main effects of the inner operating conditions. Spray cone angle is affected by the inner and outer operating conditions.3. The distance between the position of interaction point and the nozzle orifice plays a leading role in the breakup length, SMD and droplet size distribution of the internal mixed coaxial swirling liquid jet. The spray cone angle is also affected by the inner and outer operating conditions.4. The gas entrainment effect of the recirculation zone formed by the counter-swirling coaxial liquid jet is weaker than that of the co-swirling coaxial liquid jet.5. The two dimensional axisymmetric model, the VOF model, and the RNG k-e model can accurately predict the internal flow characteristics of the liquid/liquid coaxial swirl nozzle. And numerical calculation of the spray cone angle is in good agreement with experimental measurement.