Highly Expanded Flashing Liquid Jets

Results arepresented of experiments with highly expanded e ashing liquid jets along with a one-dimensional numericalmodel.Theexperimentswerecarriedoutwithliquidiso-octanejetsissuing from asmallconical convergent nozzle into a low-pressure chamber. Images of the expanding jet off the nozzle exit section were obtained from a schlieren setup using a charge-coupled device camera. Analyses of these images enabled a qualitative visualization of the e ashing jet structure and geometry. At very low backpressures, it has been observed that the emerging jet wasformedbya central liquid core,and thephasechangeprocessoccurred onthesurfaceofthatliquidcore,giving rise to a sonic two-phase e ow. In addition, it is also inferred that the freshly formed two-phase e ow proceeded further to higher velocities and Mach numbers to terminate eventually with a complex shock wave structure to adjust pressures, as usual. A one-dimensional numerical analysis is carried out. The sudden phase change in the metastable liquid jet surface is modeled as an evaporation wave, for which the jump equations are solved. Next, the supersonic expansion of the two-phase mixture downstream of the evaporation wave is analyzed in a radial direction. Theone-dimensional calculation yielded theradial position of the shock wavelocation. It has been found that the numerical results are consistent with the experimental data.