Papers by Keyword: Particle

Abstract: We present numerical simulation of particle filled resin flow through a fibrous media taking into account dual scale porosity in LCM (Liquid Composite Molding) processes. During the flow, a strong interaction between the particle motion and the fluid flow takes place at the porous medium wall or at the fiber bundle surface. A model is developed to describe the particle retention and filtration in the porous media. In this study, the Stokes-Darcy equation is solved to describe the resin flow in a mesoscopic scale. The particle retention mechanism is extensively studied taking into account the influences from such parameters as size and concentration of particles. The particle filled resin flow through a fibrous media simulation is performed to demonstrate the effect on the retention and filtration mechanism during the composites manufacturing by LCM processes.

Abstract: This paper addresses elastic analysis based on 3D finite element model for hollow sphere structures. In finite element models, which were analyzed under pressure of 1MPa, volume fraction of hollow spheres is kept at 30%, and hollow spheres are randomly located in the matrix. Five types of hollow sphere are used to form the model. All the types of hollow spheres have 60μm particle sizes, but different wall thicknesses. A comparison in stress distribution between the hollow sphere and matrix is made, which shows that in composites containing thin-walled hollow particles the maximum stress is located in the inner surface of particle wall, whereas increasing the wall thickness of hollow spheres results in getting some part of matrix around hollow spheres involved in energy absorption. Moreover, the location of the maximum stress in matrix related closely to the spatial arrangement of the particles. The study provides an insight into the micro structural performance of syntactic foam under load.

Abstract: The phenomenon that bubbles or particles are suspended at the node position of a standing wave of sound is known as acoustic levitation and has recently been applied in the fields of semiconductors, aerospace, and biology [1-3]. By using this phenomenon in this study, a new classification method has been proposed, and a device has been developed to sort objects in accordance with their densities. Unlike the conventional methods as such as centrifugal particle separation or magnetic separation, this method can separate fine particles both of metal and non-metal and without contact easily only using acoustic power. First, we derived the acoustic radiation pressure to be applied to the object from King’s theory, and then we designed and developed a twin-transducer system to apply the required levitation force. The distributions of sound pressure and particle velocity were then visualized. Finally, a series of experiments was conducted to show the capability of classifying the fine abrasive SiO₂ particles and fine iron particles (φ = 50 μm).

Abstract: The micro-sized p(styrene-1,4-divinylbenzene)/polyacrylamide(p(St-DVB)/pAM) particles were prepared by a two-step method. P(St-DVB) cores were firstly obtained via concentrated emulsion polymerization, and then the cores were swelled sufficiently and reacted with acrylamide until p(St-DVB)/pAM particles were obtain. The morphologies and compositions of p(St-DVB)/pAM particles were characterized by scanning electron microscopy(SEM) and infrared spectroscopy(IR) individually. It was proved that the micro-morphologies of p(St-DVB)/pAM particles were nearly spherical or even peanut shape. It was also found that the diameter distribution of p(St-DVB)/pAM particles became narrower with the increasing of DVB amounts, and the same trade was also observed on emulsifier amounts.

Abstract: In this paper, the AVL-Fire software was used to research the effects of ignition timing on homogeneous combustion and particle emission in a GDI engine. The result shows that the highest temperature and pressure reduce with the delay of ignition timing under the homogeneous charge mode in which gasoline is injected in the intake process. But the soot mass fraction decrease first and increase subsequently.

Abstract: At present, many Chinese cities are suffering from hazy weather. Blue sky and white cloud have become a luxury. The frequent occurrence of haze has imposed different levels of impacts on people’s livelihood and work, and people are paying continual attention to air quality. How to resolve haze problem has become an important concern of many scholars nowadays. This paper makes an analysis on the formation mechanism of haze as well as the impact and hazard of haze on people’s livelihood, and than proposes a long-term mechanism for the treatment measures to haze.

Abstract: With the development of computer technology, SPH numerical simulation method is widely used in the engineering simulation. Based on introducing the principle of SPH, these provided a reference for future SPH research on parts in the high speed collision through simulation experiment of solid high-speed collision.

Abstract: Fe-C-Ta-Cr-Ni alloy powder in diameter of 32-53 μm made by argon atomization was low-pressure plasma sprayed to produce high Cr-Ni cast iron base deposits with finely dispersed tantalum carbide particles. The as-sprayed deposit formed on a water-cooled substrate consisted of γFe, αFe and carbide. The fine precipitates of approximately 0.1 μm in the as-sprayed deposit formed on a water-cooled substrate were carbide. With increasing heat treatment temperature up to 1273 K, the carbide particles coarsened. The hardness of deposit decreases with increasing heat treatment temperature. The wear resistance of as-sprayed deposit formed on a non-cooled substrate was higher than that of the deposit heat-treated at 1273 K. The as-sprayed deposit and deposit heat-treated at 1273 K hade higher wear resistance than a commercial stainless steel.

Abstract: This paper focuses on the study of the curvatures of deflector installed on the below receiving device to effect the dust amount from the free falling particle stream. The deflector curvature was artificially controlled to limit the fugitive dust direction which was generated by the collision between the free falling bulk materials and the receiving device. This method was used to improve efficiency of the dust control system to exhaust fugitive dust, and to achieve the targets of energy conservation and emissions reduction. The experimental method was adopted to explore the relationship between the deflector curvature and the producing dust quantity. The experimental results indicated that, the dust suppression effect containing deflector contained a certain radian was more remarkable, when the height of the free falling of bulk materials was constant. The producing dust quantity decreased slightly with the deflector curvature increasing, and then increased rapidly. When the deflector curvature was 0.045 cm-1 or 0.060cm-1, the minimum of producing dust quantity could be obtained, and the dust removal effect might be significant.

Abstract: On-road particle emissions were tested in urban areas of Shanghai from a diesel bus equipping diesel particulate filter with fuel burner. EEPS 3090 particle analyzer was used for analyzing concentrations of particles in different diameters. In this paper, characterization of particles in soot loading and regeneration processes were identified, and particle reduction ability of DPF bus was analyzed. Result shows that, the averaged particle emission rate from DPF bus was degraded by 1 to 2 orders of magnitude during soot loading. Particle concentration distribution was transformed from nuclei-accumulated bi-modal pattern to uniformly multi-peaks patterns. In DPF regeneration process, particles of accumulated mode sized between 60.4nm and 107.5nm were decomposed and oxidized into fine nuclei particles of 29.4nm to 60.4nm, which increases total particle concentration. Reduction percentage of particle number per kilometer of DPF bus for soot loading and regeneration process reaches respectively 97% and 83.2% compared with normal diesel bus.