Numerical Simulations On Impact Of Moving Shock Wave On A Liquid Droplet

The evolution of droplet morphology under shock wave impact is a canonical prob-lem in the compressible multiphase interface flow.It has a great variety of scientific relevances and engineering applications.In this thesis,numerical simulations have been performed to study the shock/droplet interaction.Some salient flow features and the underlying physics are discussed.The results and conclusions are briefly given as fol-lows:(1)The shock/droplet interaction before a standing wall is studied numerically.It is found that the influence of varying L is very complex as it changes the impacting regime of the reshock on droplet.The increase of the shock Mach number Ms is to intensify the flow features,and cause more complicated droplet deformation.The maximum wall pressure in four typical cases is closely monitored,and it is indicated that the second peak value is always maximum and occurs near the axis.This finding has great significance in relevant engineering applications.In addition,the kinematic research demonstrates that the droplet moves downstream towards the wall at the early stage,then turns to move upstream away from the wall.The impact between the droplet and the wall never happens.(2)Elliptic droplets are employed in studying the shock/droplet interaction,aimed to explore the influence of initial droplet shape on droplet's motion and deformation.It shows that,for elliptie droplets with different axial leength ratios e,signifiecant differences occur in wave structures when Ms increases.e and Ms both have oobvious effects on the long elliptic droplets deformation.Two typical deforination modes,which are respectively governed by the shear effect and the impact effect,are found by varying these two parameters.Moreover,the deformation rate of the droplet is mainly affected by Ms,while affected less by e.In addition,The center-of-mass velocity increases with a decreasing e.The drag coefficient Cd demonstrates violent oscillation because of the vortex shedding in the wake,but its mean value varies around 0.9 in the early deformation stage.