Investigation Of The Dynamics Characteristics Of Droplet Under Supersonic Conditions

It is a classic multiphase fluid mechanics problem that liquid droplets will be deformed and broken when exposed to supersonic flow environment suddenly,which includes the study of compressible gas dynamics,interface stability,interface dynamics evolution and other fields.At the same time,this kind of phenomenon also exists widely in daily life and engineering application.Based on the deformation behavior and mechanism of droplet deformation under supersonic conditions,the deformation and fracture process of submillimeter water droplets(0.44?1.09)under shock shock is studied experimentally in a horizontal shock tube.The shock Mach number range is 1.07?2.11Ma,through the high-resolution high-speed camera combined with the shadow method to record the deformation and fracture characteristics of droplets under different crush modes,and obtain the liquid in the form of Bag breakup?Bag and stamen breakup?Shear or Stripping?Catastrophic or Shattering.The shadow image is dropped,and the motion parameters of the droplet are analyzed in a spatiotemporal relationship.Through the non-dimensional analysis of experimental results and motion parameters,the paper draws the following conclusions:(1)In the stage of droplet deformation,the dimensionless lateral width shows a linear change with the dimensionless time;(2)In the same fragmentation mode.Under aerodynamic conditions,the dimensionless transverse maximum deformation width of the droplet decreases with increasing diameter;(3)When the initial diameter of the droplet is the same,the dimensionless lateral maximum deformation width of the droplet in the explosive crushing is compared with other broken modes.The state is significantly reduced,the dimensionless transverse maximum deformation width of the bag-shaped fracture,multi-modal fracture and shear fracture is between 1.15 and 1.61,and the dimensionless transverse maximum deformation width of the explosive fracture is between 0.21 and 0.68.At the same time,through the measurement of the completion time of the droplet deformation,we found that the time for the droplets to be flattened in different fracture modes is not the same.It is found that the completion time of the droplet deformation,the multi-modal fracture and the shear fracture is closer.And the explosive crushing is much smaller than the three.(4)The curve of the dimensionless upwind displacement of the droplet with the dimensionless time is parabolic,indicating that the magnitude of the acceleration is constant;(5)Under the same aerodynamic force,the initial diameter of the droplet moves at the velocity of the droplet along the airflow direction.The decisive role in the movement of the droplet along the direction of the gas flow decreases with the increase of the initial diameter of the droplet;(6)The initial diameter of the droplet affects the acceleration of the windward surface of the droplet is greater than the We number;(7)In the liquid Under the premise that the initial diameter of the droplet is similar,the acceleration of the droplet increases with the increase of the We number,from the bag-shaped fracture to the multi-modal fracture to the shear fracture and finally to the explosive crushing,the acceleration of the droplet increases sequentially,and the explosive type The broken droplet acceleration is significantly improved compared to the first three fracture modes.