Papers by Keyword: Drop Impact

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Authors: Shu Yi Yang, D.S. Liu, Z.J. Wen, Y.F. He
Abstract: In view of complexity internal structure of mobile hard disk and according to the principle of quality equivalent, a finite element model of mobile hard disk was established. Finite element simulation with dropping impact of mobile hard disk was made based on uniform design. A neural network model of nonlinear mapping relations was established between shell thickness,actuator arm thickness, cantilever thickness and pivot bearings stiffness of mobile hard disk with shell stress,disk interface stress and space with head and disk. The difference is less of the prediction values with the ANN(artificial neutral network) and the simulation datum with the FEM(finite element method). This indicates that the method is effective and may provide theory evidence for optimization crashworthiness design.
Authors: Xiao Fang Yuan, Jing Yin Li, Bin Zhang
Abstract: The impact processes of water and ethanol drops on a rotating horizontal aluminum disk were recorded and analyzed using a high-speed digital camera together with an image analysis program. The angular velocities of the disk were altered to study the effect of surface tension of drops on drop impact processes. The experimental results show that a lower surface tension will result in a higher tangential spread factor and a lower receding rate during the receding stage, for the drop impinging and depositing on a rotating disk. In addition, a lower surface tension of the drop tends to promote the occurrence of splash. The experimental results further verify a proposed correlation of splash-deposition boundary for drops impinging on a rotating disk. Both drops, though they have a quite different surface tension, experience four stages, with two new stages different from those of drops impinging on stationary surfaces. Their tangential spreading factors both increase obviously with the tangential velocity at the impact point, while their radial spreading factors vary a little.
Authors: Young Shin Lee, Hyun Seung Lee, Sung Hwan Chung
Abstract: Radioactive waste is shipped in casks designed to prevent the release of the radioactive material into the environment in normal accidental conditions. So, the cask must maintain its integrity such as shielding characteristics and leak tightness after the 9m free drop. In this paper, we consider several types of radioactive material transport casks. The drop scenarios for the integrity evaluation are 6 drop cases. The dynamic analysis is performed by applying the various free drop angle of cask for research the dynamic impact behavior and integrity evaluation of a radioactive material transport cask. As a results of impact drop analysis on radioactive material transport cask, the container maintain structural integrity evaluation in 9 meter free drop conditions.
Authors: Jun Jun Tao, Jun Qin, Xue Han, Yong Ming Zhang
Abstract: A numerical study based on VOF model has been carried out to investigate the dynamics of water droplet impact on solid surface in microgravity in comparison with that in normal gravity to discuss the differences of the extinguishing mechanism of water mist in different gravity level. Water droplets with different initial diameters and impact velocities were considered. The simulated results show that the deformation process in microgravity lags behind that in normal gravity. And it was also found that Dmax and spread velocities are smaller in microgravity as the potential energy decreases and the time taken for a liquid droplet to reach its maximum spread has no obvious regularity. Hence, the effect of cooling the fuel surface and diluting fuel vapour with water mist in microgravity may be not as good as that in normal gravity.The critical impact Weber number for water droplet breaking up in microgravity is lower than that in normal gravity as the reduction of the value of Bond number, which may result in diluting fuel vapour with water mist in microgravity being more effective than that in normal gravity in some case.
Authors: Jing Yin Li, Xiao Fang Yuan, Qiang Han
Abstract: Experimental studies of a water drop impinging on a rotating disk using a high-speed video camera have been performed. The photos of the impact were analyzed in detail. Three kinds of the deposition patterns were observed with the variation in Rossby number. It is found that Rossby number plays an important role in the deposition process of the drop impacting on the rotating disk, leading to some new stages not observed for drop impact on a stationary plate.
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