Advanced Materials Research Vols. 774-776

Abstract: The maximum vapor fraction in the air decreases with the temperature falling. For the air which has the high humidity, the redundant vapor will condense into fog or freeze into ice if the moist air attained a new saturation in a lower temperature. The buses running in the north cold areas usually face this problem in winter. According to the theory of jet impingement heat transfer, this thesis analyzed the influences of angle between the windshield and impinging jets and also the distance between vents and dashboard edge on defrosting by a simplified bus model. It also put forward some suggestions about defrosting on buses.

Abstract: A digital car model was taken as study object, and the influence of the regulating seam to an open type automobile wind tunnel was discussed by comparing simulation results with test data.The results show that the regulating seam changes the flow field around the collector, reduces the size of unsteady flow field and the flow in test section is uniformed better. Thus, the regulating seam shouldn’t be removed when simplifying the wind tunnel model in the simulation. This conclusion will provide theoretical basis and data support for better virtual reproduction and numerical simulation of a wind tunnel.

Abstract: Displacement control unit is an important part of hydraulic system for screw distributor. By adjusting the angle of swashplate, it can change the flow rate of pump and rotating speed of screw distributor. The rotating speed of screw distributor has influence on quality of road. The mathematical model of displacement control unit is presented. Its dynamical characteristics are analyzed. The mathematical model includes a reset spring gradient. The reset spring gradient is much smaller than the hydraulic spring rate, the effect of the reset spring gradient can be neglected. So an inertial element can be substituted by an integration element.

Abstract: One of the reasons of chemical explosion is the grease enters the oxygen cylinder when fill and use it. The grease in the cylinder will be oxidized, which can elevate the temperature. The high temperature will decrease the ignition point of grease, and then the combustion and explosion will occur. To prevent such accidents in the cylinder filling process, the temperature of the gas in the cylinders must be strictly controlled. In this paper, the heat transfer of the cylinder wall is studied by the method of calculation and the pressure-temperature law of outer wall of the cylinder is obtained. Therefore, this paper provides a reference for chemical changes in the cylinder filling process. The grease should be degreased first before the cylinder filling process. The temperature of cylinder should always be ensured normal during the cylinder filling process.

Abstract: Experimental research on damage to fracture conductivity caused by fracturing fluid residues has been done for the first time in China using FCES-100 (Fracture Conductivity Evaluation System). In the experiments, the degree of damage to conductivity caused by different types and concentrations of fracturing fluids were studied in the condition of different concentrations and types of proppants. The mechanism of damage to conductivity was studied and some methods on how to decrease the damage were brought forward, which is significant for the research on development of fracturing fluids and also for field treatments.

Abstract: Based on the implementation of the project of steam induced draft by one factory, heat balance calculation was employed to calculate the coal consumption rate between steam-driven and motor-driven induced draft fans. Besides, an all-purpose economic evaluation method was employed to analyze the investment recovery term and sensitivity of the two plans. The results show that it needs 2.8 years to recover the full cost based on the standard coal price for RMB 900 yuan/t, the electricity price for RMB 0.43 yuan/(kW.h). The evaluation also provided other recovery terms in different electricity price and coal price.

Abstract: Electromagnetic vibration pump is one type of first proposed new household positive displacement pump.It is mainly used to transport water and other low viscosity liquid. It has many advantages including small flow, high head, simple structure,good self-priming performance. Electromagnetic driving method was combined with displacement pump in vibration pump for the first time. Its specific speed can reach below 10,and this is a breakthrough in super-low specific speed pump design. The working principle of electromagnetic vibration pump and its performance were studied in the paper. each of these problems is further discussed and explained in order to point out the research field for the development of electromagnetic vibration pump later.

Abstract: Placement in the middle retaining wall package, aimed at controlling the flow of liquid steel forms, so that movement of a reasonable level remained stable, while reducing interference from turbulence and dead zones, molten steel in order to extend the average stay of removal in favor of inclusion to improve the cleanliness of molten steel. Keywords:Tundish; Retaining Wall; Flow field; Mathematical Modeling; Inclusion;Optimization setting

Abstract: This paper is based on Reynolds stress model and uses a very important tool called ICEM CFD,which is integrated in ANSYS Workbench to mesh the cyclone-separator sand trap. From the Hexahedral structured meshing and analysis of its internal gas movement of the cyclone-type sand trap, the results are shown that mesh quality meets the requirements of solver by using the advanced O-grid and Y meshing technology in the software of ICEM CFD. Moreover, the existence of the short-circuit flow and the secondary flow is proved in the analysis of speed of the gas phase in the cyclone-type sand trap. From the information above, optimize designers can chance the structure of the cyclone-type sand trap in order to improve the separation efficiency of the cyclone sand trap and then to provide more valuable parameters for assessing and analyzing the impact of stubble height and surface crop coverage on wind erosion.

Abstract: This paper aims at study the technology of flow active control to increase the wing lift and weaken the wing drag by using the method of fluid mechanics. There are two new active control methods proposed in this paper. In this article, the computational method is expanded to a three-dimensional wing model to verify the validity of the new active control technology. Research shows that the partial active deformation can improve the aerodynamic characteristics of airfoil by appropriate parameters optimize, moreover the effect of rotation was better. In the condition of low Mach number and rotational control, the lift coefficient can be increased 11%, the drag coefficient can be decreased 40%. The shock wave will move backward by control in the condition of high Mach number. The control effect of 3D model is not as good as 2D model.