Advanced Materials Research Vols. 655-657

Abstract: The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with flow visualizations. The results obtained allow defining five distinct zones in the bucket from the flow patterns. The flow patterns in the buckets are analyzed from the results. An investigation of the momentum transfer between the water particles and the bucket is performed, showing the regions of the bucket surface that contribute the most to the torque. The study is also conducted for the backside of the bucket, evidencing a probable Coanda interaction between the bucket cutout area and the Water jet.

Abstract: This paper describes the use of a commercial CFD code, FLUENT, to model fluid flow in thermal flow reversal reactor (TFRR) for lean methane oxidation. A two dimensional model is used. Pressure loss in ceramic bed of TFRR was focused on, and the effects of main factors are presented. The results show that the contours of static pressure in ceramic bed are slightly inclined due to the gradually variation distribution of velocity; the pressure field in distributing header is more uniform than that of collecting header; the ratio of header’s height to ceramic length influences the pressure loss most and with the increase of the ratio the pressure loss of TFRR decreased dramatically; the pressure loss increased with the increase of volume flow rate. The structure of headers is the most important factor which affects the pressure loss of TFRR.

Abstract: In this paper, water flow boiling characteristics within vertical rectangular thin channels were numerical analyzed. By the method of numerical simulation, the isolation bubbly stream flow patterns adapt to the non-restricted and restricted thin channel were obtained and the influence of channel-scale on the boiling flow pattern characteristics are analyzed. Study shown that the system pressure drop is increased with the decrease of the channel width; the heat transfer coefficient shows a decreasing trend after the first increase along with the increasing dryness; the decline of channel scale will lead to increasing of the average heat transfer coefficient.

Abstract: In anechoic chambers, the flat-walled multilayered acoustic lining systems are cheaper and easier to install than conventional wedge type systems. Sequence, material and thickness of layers are all design variables. By choosing the right configuration, the acoustical performance and overall thic- kness of flat-walled multilayered systems can be comparable to conventional wedge systems. In this study, the materials considered include air and poroelastic materials such as polyurethane foams, melamine foams, and glass wool. In order to evaluate acoustical performance of a given configurati- on, the poroelastic materials are modeled using Biot’s formulations instead of a simpler impedance method to get more accurate results. A genetic algorithm implemented within ModeFRONTIER opti- mization software was used to select configurations which have a cut-off frequency of 100 Hz or less. The configuration that met this requirement with the smallest overall thickness was determined optimal. This configuration has an overall thickness of 65.8 cm and is composed of 4 different polyurethane foams. Since a considerable difference was observed between the cut-off frequencies obtained using Biot’s model and the simpler impedance method, this justifies the use of Biot’s model in the optimization.

Abstract: Crash-box equipped at the front end of a car, is one of the most important automotive parts for crash energy absorption. In case of frontal crash accident, it is expected to be collapsed with absorbing crash energy prior to other body parts so that the damage of the main cabin frame is minimized and passengers may be saved. Crash-box usually was made a mental thin walled tube. In the paper, automobile crash-box at low-velocity impact was studied by using Finite Element Method. The FE model of the tube was validated by comparing the experimental results and FE model results. Results show that on average the difference of these was within 10％.The good correlation of results obtained show that the numerical analyses are reliable. Crash-box of carbon steel and aluminum alloy materials are compared, it indicates that the peak impact force and maximum energy absorption have certain effect to energy-absorbing component with different materials.

Abstract: The influences of the two working parameters of elastic-friction seed-metering device—motion velocity (v) and rotate velocity (n) on CV of seeding uniformity in the lines (v1), CV of seeding consistency between the lines (v2) and CV of seeding rate stability (V) are analyzed by two factors quadratic orthogonal rotational combination experimental design. With DPS 9.50 data processing system these mathematical models are set up. There is a very significant regression between v, n and v1, v2, V and all factors are significantly at level α=1%. The results show range of v1 is at 3.0996%-5.8912%, range of v2 at 4.1105%-5.9297%, range of V at 1.6274%-2.8504% in the values range of the two factors.

Abstract: On-line monitoring of the insulating state of metal oxide surge arresters (MOA) is monitoring its resistive leakage current. This paper analyses the common detection methods of resistive current, pointed out the problems. According to the relationship among the grid voltage and the flow through the leakage current of MOA, the resistive and capacitive current, put forward a new resistive leakage current detection method, and established a mathematical model. Using this mathematical model, new detection method can be verified by simulation. Confirmed that the new method can effectively reduce the impact of the power grid of the third harmonic voltage and phase coupling capacitor, this create a precise measurement for MOA resistance current online testing.

Abstract: Stress and dynamic characteristics analysis of Multilayer composite flywheel to study its natural frequency, stress and displacement distribution was investigated in this paper. Combined with the rotor structure characteristics, a calculation model was established on the basis of anisotropy symmetric theory. The analytic formulas with flywheel rotor at working speed were obtained. Established the finite element model of the rotor. The radial , hoop stress, radial displacement and dynamic characteristics at a random point were analyzed completely．The results indicate that the safety factor and the natural frequency meet the design requirements.

Abstract: On ca-cored wire feeding in ladle, there are surface feeding stage and inner feeding stage. China is still in the surface feeding stage. The gas rotary lance was developed for the present condition of the wire feeding devices in China. The water simulation test and the pressure water simulation test were carried through. The vortex on the surface of the liquid and the cavity, the recirculation and rotary in the liquid were observed in the water simulation test. The characteristic curves of the lance coupled with the different wires were disclosed. The lance can be used with the guide pipe directly.

Abstract: This paper introduces the effect of quenching parameters on deformation of gear by oil quenching gear. These influences have relationship with many factors. By comparing and evaluating the main influence factors, provide basis for choosing the best carburizing and quenching process.