Papers by Keyword: Particle Velocity

Abstract: The paper presents theoretical and experimental results on the synthesis of ash-based microspheres using the high-temperature plasma treatment. The dynamic motion of particles and their melting are considered depending on the initial porosity of the raw material modified by 3200K plasma treatment. Physicochemical studies relate to the original raw material and microspheres produced therefrom.

Abstract: The helical trough of a vibratory elevator induces, by its helical vibratory motion, a complex behavior to the transported parts. The paper analyses the displacement of a singular plate material particle on the cylindrical helix of a vibratory elevator, by decomposing the particle motion on slide and jump phases, dependent on the functional specific features of the vibratory equipment. A computer model of the particle motion was developed to study the theoretical average transportation velocity on the helical vibrating surface.

Abstract: This paper aims to investigate the particle dynamic behavior in a rotating drum operating in a rolling regime under different rotating velocity, based on experimental results and simulations. Simple superphosphate fertilizer (SSP) was used as particulate matter in the current study. The Eulerian–Eulerian multiphase model along with the kinetic theory of granular flow was used in the simulations. In order to evaluate the simulation results, velocity distributions of the particulate phase were compared with experimental data. The experimental particle velocity distribution was obtained by using a high speed video camera. The numerical simulation results showed significant insights towards understanding of the particle dynamic in a rotating drum. The simulated results of particle velocity were in good agreement with the experimental data.

Abstract: Optimal techniques of coating a copper underlayer before silvering aluminum contacts by detonation were developed. Velocity of particles in flow, adhesion of copper layer, and porosity of coating were taken into account. The determined sputtering conditions allow improving quality of silver coating on the contacts.

Abstract: This study investigated the effects of carrier gases (He and N₂) on the microstructure and properties of Ti coating layers to manufacture high-density Ti layers using the cold spraying. Cold spray coating layers manufactured using He had denser and more homogenous microstructures than those produced using N₂. Layers manufactured using He gas showed porosity of 0.02% and hardness of 229HV, which are better properties than the porosity (0.4%) and hardness (177HV) of N₂ coating layers. The bond strength of coating layers manufactured using He recorded higher value of 74.28MPa than that manufactured using N₂. This could be attributed to the fact that, when coating layers are manufactured using He gas, the powder can be easily deposited because of its high particle impact energy, facilitating the plastic deformation of the particles.

Abstract: It is known that the micro-structure of coatings produced by low pressure plasma spraying (LPPS) is significantly different from the one produced by atmospheric plasma spraying (APS). Because of the different pressures between the inside and the outside of the plasma gun, the exiting plasma jet experiences unconventional behavior related to supersonic expansion at reduced pressure. In this work, the DPV 2000 system was used to measure in-flight particle velocity and temperature. Alumina powder was injected as sprayed particles under 150 mbar conditions. These preliminary researches are the starting points for development and optimization of this process.

Abstract: Abstract. To realize the sound pressure unit directly, the method of sound pressure measurement based on acoustic particle velocity was described. In order to get a simple acoustic field, a travelling wave tube was designed. The sound pressure distribution obtained by microphone along the tube was measured. The result showed the acoustic field inside the tube could be considered as travelling wave and the sound pressure is equal to the product of the air density, sound speed and the particle velocity. The laser Doppler Anemometry was used to measure the particle velocity in the acoustic field. The modulated Doppler signal was obtained by measurement system. With the spectral analysis of Doppler signal and the signal model, the particle velocity was obtained with the Bessel function analysis. The comparison of sound pressure measured by microphone and the value deduced from the velocity measured by laser Doppler system shows that deviations between two methods were 0.04 dB at 650 Hz and discrepancies were less than 0.34 dB at frequencies from 300 Hz to 1k Hz.

Abstract: Average particle velocity measurements were carried out in a conical-cylindrical spouted bed made of acrylic. In this study an intrusive fiber optical technique which is based on a cross-correlation function between signals from its two channels was used. For a non-intrusive measurement in order to compare with the intrusive technique, images of particle movement were recorded using a high-speed video camera. The experiments were conducted in differents air velocity conditions above the minimum spouting velocity. The latter method was limited in velocity measurement only near the spouted beds wall inasmuch as the spouted bed used was a three dimensions one. On the other hand, the fiber optical is a promising technique for measuring particle velocity distributions in a three dimensions spouted bed. To predict the minimum spouting velocity in order to use this result in the measurement techniques investigation, simulations were carried out using the Eulerian-Eulerian multiphase model.

Abstract: The hydrodynamics in a gas-solid draft tube-lifted air-loop reactor (GSALR) was investigated systematically using experimental measurements. To demonstrate the gas-solid flow pattern, the upward particle velocity, downward particle velocity and time-averaged particle velocity in four regions of the GSALR were measured by optical fiber probe under different superficial gas velocities. The experimental results show that the downward particle velocity distributes uniformly along the radius in the four regions, but the radial distributions of upward particle velocity and time-averaged particle velocity are core-annulus or heterogeneous structure in the three regions (distributor affect region, draft tube, gas-solid diffluence region), which have the common feature of aggregative fluidization occurred in normal fluidized beds. The operating condition such as superficial gas velocity in draft tube has different effects on the radial distributions of upward particle velocity, downward particle velocity and time-averaged particle velocity in each region. Analysis of the distributions of upward particle velocity, downward particle velocity and time-averaged particle velocity leads to suggestions regarding optimization of the design and provides further theoretical basis for industry application of GSALR.

Abstract: Simulations of the supersonic flow field inside and outside of the Laval nozzle with single hole and nine holes were carried out based on the computational fluid dynamics method. The effects of different standoff distance and particle diameter on impact velocity of Cu particle spraying from single hole and nine holes were investigated firstly. The results show that the particle velocity obtained with the nine holes nozzle is higher than that of the single hole nozzle under the same standoff distance, and the smaller the standoff distance, the higher the particle velocity may be obtained with the nine holes, and the higher particle velocity may be obtained with smaller particle diameter for particles with diameters of 1 ~ 15 μm. Furthermore the effects of different spraying pressure and temperature on particle velocity of Cu particle spraying from the nine holes nozzle were also studied. And the simulations indicate that the higher the spraying pressure and temperature may make the particle spraying with greater velocity.