Experimental Study On The Dispersal Of Liquid And Solid Particles Induced By Shock Wave

Aerosols are solid or liquid molecule clusters which suspend in gas medium for a long time. They have original chemical and physical characteristics and specific motion patterns. Besides being used in meteorology and fire protection fields, aerosols are also widely used in military field. The formation mechanism of aerosols and the parameters of aerosol cloud are main points in the investigation of aerosols in military field. Based on theoretical studies and experimental investigations, this dissertation studied the dispersal of liquid droplets and solid particles induced by shock wave and the formation processes of aerosol clouds using self-designed shock tubes. The specific contents are as follows:(1) On the basis of theoretical and experimental investigation of the interaction processes between shock waves and liquid droplets, the interaction process between shock waves and liquid films are investigated theoretically after analogy analysis and bringing in the non-dimensional parameters, including We and Oh. The filed condition after the interaction between shock waves and solid particles was also analyzed from the energy conversion point. The change of shock wave state and flow field conditions after the interaction between shock waves and objects were also studied theoretically based on the results of several experiments.(2) The interaction between shock waves and liquid films were investigated experimentally and the formation, breakup and dispersal of liquid films were studied together. In the experiments, Mach number, kind of liquid and the thickness of liquid film are three importance parameters. The influences of the three parameters on the breakup and formation of aerosol cloud were analyzed systematically. The results indicated that induced by the same shock wave, there existed closely relationship between the size of cloud and the thickness of film. For water and glycerol, the dispersal performance of water was better than glycerol because of the differences of their viscosities. PDPA device was used to measure the diameter distribution and velocity distribution of the aerosol cloud formed. It is found that the average diameters of water particles decreased with the increase of dispersal distance and the vertical and horizontal velocities both decreased and then remained stable. Vertical velocity is bigger than the horizontal one at the original state. For the mixture between water and glycerol, the average diameter of liquid particles decreased and then increased with the increase of glycerol content and the velocities both decreased and then remained stable. Finally, several models were established using data obtained in the experiments.(3) Pressure measurement and shadow graphic technology were combined to study the interaction between shock waves and solid particles. The dispersal traces were also investigated. Several models are established and numerical simulation was carried out, which was in good agreement with the experimental results. Based on the investigation between shock waves and particles, the interactions between shock waves and materials with different densities were performed. The results indicated that the material had different variations induced by the same shock wave for the differences of their physical parameters.(4) A number of field experiments were carried out using the results obtained in the laboratory. The dispersal and explosion parameters of PO fuel and thermobaric explosives induced by blast shock wave were mainly investigated. Because of the physical features of PO fuel, the dispersal effect is perfect which also leads to the enlargement of damage range of PO fuel. Compared with the blast perfomance of TNT, it is found that the high temperature range and the duration of high temperature of solid thermobaric were enhanced obviously because of its dispersal behaviour and interaction with air.