Advanced Materials Research Vols. 557-559

Abstract: Finite element methods for the elliptic variational inequality of the second kind deduced from friction problems or nonlinear materials in elasticity have been discussed. In this paper, the finite element method with numerical integration for the second type elliptic variational inequality is considered and an error estimate is proved.

Abstract: A simulating is researched on the wind power system based on the direct drive PM synchronous generator. It’s maximum power point tracking (MPPT) method. According to the grey system, GM (1,1) model is used to predict the dynamic process of the complex system. When it arrives the maximum power point or so, the least square method is evaluated basing on the experimental data, then calculated the point. Finally the maximum relative error is given between the evaluatal value and experimental data. The results are testified the variable speed system’s good traits of capturing more power and system reliability.

Abstract: This Paper expounds the relation between spherical triangle and triangular pyramid in a new perspective. Thus, the graphic method to address spherical triangle problems by descriptive geometry is put forward, which broadens the research field of spherical triangle problems.

Abstract: Trefoil-hole baffles have good thermo-hydraulic performances as the support of heat pipes, however the published research paper is relatively limited. The present paper investigates the shellside thermo-hydraulic characteristics of shell-and-tube heat exchanger with trefoil-hole baffles (THB-STHX) under turbulent flow region, and the variations of shellside Nusselt number, pressure loss and overall thermo-hydraulic performance (PEC) with Reynolds number are obtained for baffles of varied pitch with the numerical method. CFD results demonstrate that the trefoil-hole baffle could enhance the heat transfer rate of shell side effectively, and the maximal average Nusselt number is augmented by ～2.3 times that of no baffle, while average pressure loss increases by ～9.6 times. The PEC value of shell side lies in the range of 16.3 and 73.8 kPa-1, and drops with the increment of Reynolds number and the decrement of baffle pitch, which indicates that the heat exchanger with trefoil-hole baffles of larger pitch could generate better overall performance at low Reynolds number. Moreover, the contours of velocity, turbulent intensity and temperature are presented for discussions. It is found that shellside high-speed jet, intensive recirculation flow and high turbulence level could enhance the heat transfer rate effectively. Besides good performance, THB-STHXs are easily manufactured, thus promise widely applied in various industries.

Abstract: Slide way is the base in building the large structure. Use float and drag method to install the large structure influenced by the hoisting equipment ability. To control the height of the large structure, need to add a girder structure at the bottom of the large structure after building it to make the structure hoist it to a few or dozens of meters to ship. To make force analysis and grasp the fulcrum stress of the large structure and the intensity of the girder structure and the slide way stress to make the system safe and provide technical support for the carrying out of the engineering.

Abstract: The conventional ethanol fermentaion is a typical inhibitory process, leading to low productivity and yield. A new ethanol fermentation process coupled with gas stripping and vacuum flash, named as strip-flash fermentation, is proposed. The process is provided with the advantages of both stripping fermentation and flash fermentation, and improves the ethanol productivity by increasing the in-situ ethanol removal. And a model of flash-strip fermentation process was established. The theoretically analyses indicate that increasing gas flux and liquid phase recycling ratio can help to enhance productivity and yield of strip-flash fermentation process, and comparison to striping fermentation or flash fermentation, flash-strip fermentation has shown a better productivity. The results has also shown the possibilities of further application and optimization of this process.

Abstract: Free-wheel hub plays an important role in automobile starter system, so there is higher quality requirement on geometry and precision. In order to improve the efficiency and comprehensive functions of the part, according to the features of the lower part with involute small module internal helical spline, the rotary forming technology was put forward, and the forming process was simulated by the DEFORM-3D software. In the die design, the use of rotary punch made the process of rotary forming achieved in common hydraulic press, and can serve as an important reference to the design of forming process and die structure of similar part.

Abstract: In view of the fact that the two-dimensional square pore network model screened many microstructure features and transfer characteristics inside porous media, a fractal pore network model for unsteady drying process of natural porous body was developed on the base of fractal geometry theory and transport process principle, which took various factors into consideration, such as the liquid-phase flow, vapor-phase diffusion, temperature gradient, and pore microstructure characteristic.

Abstract: A new technology of high efficiency concasting based on inner-outer couple cooling of molten steel in a mould has been advanced, that is to set an inner cooling apparatus, U shape pipes, in a mould. The flow status of molten steel in mould with inner cooling apparatus is analyzed by using fluid dynamics analysis software FLUENT, and compared with that without inner cooling apparatus. It is found that the inner U-shape cooling apparatus can make molten steel flow with a lower impact depth which is favourable to inclusion in steel floating up.

Abstract: In order to validate the model established in reference [1], a drying experimental study was conducted, and numerical simulation was carried out under the same environmental condition. The experiment and simulation results indicated that the fractal pore network model could explain the drying process of real porous media effectively, the drying curve of fractal models was more consistent with the real drying curve than that of regular models, and its moisture fields well reflected the drying kinetics characteristic of real porous media. There was no correlation between the pore fractal dimension and the drying time, and the simulation result of unsteady-state heat transfer was more consistent with a real drying process than that of steady-state heat transfer for the convective thermal drying.