Papers by Keyword: Collision Energy

Abstract: In mechanical equipment interacting with impingement particles, worn surface morphology of parts and components is formed by an accumulative action of a large number of single-particle erosions. To exhibit the mechanism of multi-particle erosion of target, three physical experiments and Discrete Element Method (DEM) simulations of erosion of iron target by the two vertical impingements of Al₂O₃ particle are carried out under three different landing errors x of the two impingements. The experimental results showed that each of two overlapping worn morphologies by the two impingements has an spherical cap shape. When x is larger than radius R₁ of worn morphology of target by the first erosion, two morphologies with an spherical cap shape are very close in size; while the size of worn morphology by the second erosion increases with the decrease of x, when x is smaller than R₁. The predicting worn morphologies by DEM are almost consistent with the experimental results, where the maximum relative deviation in size of worn morphology is 2.98% in the direction along x, and is 3.93% in the direction perpendicular to x. All these proved the effectiveness of the DEM model in predicting erosion of target by two impingements of particle.

Abstract: The generation of plasmas and the initiation of electrical breakdown are realized by the phenomenon of electrical discharge which is provoked when we apply a sufficient electric field in a gas. Consequently the free charges are accelerated, new charged particles are created and others are destructed. This can be ranged in four phenomena: elastic collision (recombination), attachment, excitation and ionization. The aim of this paper is to study the basic phenomena in an electrical discharge in the case of Oxygen O₂. Monte Carlo Simulation is used to follow the random trajectory of free charges determining in each path many parameters of the discharge. To determinate electrical and physical parameters, we have used the sampling laws. The spatial distributions of space charges (electrons, positive and negative ions) are also obtained. The determination of electrical field depends on distributions of charged particles obtained by solving the Maxwell equations.