Applied Mechanics and Materials Vols. 291-294

Abstract: Cuda has been widely used in computational fluid dynamics due to the powerful abilities of floating point arithmetic on gpu.This paper solved the Navier-Stokes equations of two dimensional incompressible flow using parallel programming on cuda. The finite volume method and the second-order upwind discretization scheme were used in the simulation.The speed of serial c program and the cuda based program were compared and we also compared the two programs on different hardware.The simulations got high precision results,which showed that the cuda based parallel computing is much more efficiency,and the parallel algorithm could get a more than 10 times the acceleration.

Abstract: The paper presents numerical simulation of blade channel vortex in a low head Francis turbine using OpenFoam code. A mixture assumption and a finite rate mass transfer model were introduced to analyze blade channel vortex. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results have shown that using cavitation model to analyze blade channel vortex is very effective.

Abstract: The paper presents numerical analysis of cavitating turbulent flow in a high head Francis turbine with draft tube natural air admission at part load operation. Analysis was performed by OpenFOAM code. A mixture assumption and a finite rate mass transfer model were introduced. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. The pressure distribution and the flow of air in the draft tube are analyzed in detail. Simulation results show that the pressure fluctuations on the draft tube wall can reduce with natural air admission.

Abstract: The fouling in the heat transfer devices of power plants, not only changes the fluid flow state designed, but also counteracts the heat transfer, so the equipment safety and economy are reduced. The adsorption and deposition about fouling is a quite complicated chemical and physical process, and it is difficult to obtain an accurate and reasonable model and its engineering application. Therefore, under some different conditions such as velocity, temperature and concentration of fouling and pipe position, the numerical simulation is obtained in the power plant steam cooler. The temperature inside the pipe is gradually decreased with the velocity. At the same time, the fouling increases in the first half of the exchanger pipe, and easily appears near regions of entrance more and more. The fouling may occurs at the outlet position of the heat exchange tube. Under the same conditions the heat exchange tube near centre line is easier to bring the fouling.

Abstract: The new regulations on emissions and energy efficiency in the amendment to MARPOL Annex VI will become effective on January 1, 2013. The old-type marine main engine is difficult to come up to the new standard. Determining how to reduce the NOx, CO2 emissions and improve energy efficiency of ships draws a lot attention. The adaptability of marine dual fuel engine on the new regulations, EEDI and EEOI was studied, and the prospect of dual fuel engine is analyzed in this paper. To some extent, it has guiding meaning in the development of the marine main engine.

Abstract: Gunpowder was released in an instant when the pill fly out of the shell during the firing, and then formed a complicated flow fields about the muzzle when the gas expanded sharply. Using the 2 d axisymmetric Navier-Stokes equation combined with single equation turbulent model to conduct the numerical simulation of the process of gunpowder gass evacuating out of the shell without muzzle regardless of the pill’s movement. The numerical simulation result was identical with the experimental. Then simulated the evacuating process of gunpowder gass of an artillery with muzzle brake. The result showed complicated wave structure of the flow fields with the muzzle brake and analysed the influence of muzzle brake to the gass flow field distribution.

Abstract: On the base of experimental observations of mass loss rate in dependance of time in isothermal condition in circulating air atmosphere was determined the moment of lignocellulosic materials ignition. Experiment was performed in an electrically heated hot-air furnace according to ISO 871 standard (Setchkin furnace) in conjunction with precision scales. Experiment was performed with ignition source. The ignition source was kanthal wire. Experiment was performed at one temperature, three positions of samples in the oven and various air-flow speeds. Pure cellulose as a model compound was impregnated by water solution of KHCO₃ and (NH₄)2HPO₄.

Abstract: In this paper, a speeding-up inlet was developed to increase the free stream velocity in the marine current in order to increase the input energy of turbine. This study was conducted in the Hydrodynamics Laboratory at Zhejiang University of Technology. By using high-speed camera, acoustic Doppler velocimetry (ADV), the influence of area ratio and length-diameter ratio on rotational speed of the turbine was experimentally investigated. Experimental results showed that both area ratio and length-diameter ratio have significant influences on the rotational speed of marine current turbine.

Abstract: The situation of the global energy is tending to be in short supply, but geotherm is the inexhaustible renewable energy. Extracting reservoir geothermal water from old oil well can achieve economic benefits of oil - heat joint production. Since 2005, Huabei oilfield has been engaging in geothermal comprehensive utilization research projects and developed the large displacement electrical submersible pumps suitable for high temperature. For the operation management of this equipment, the working condition diagnosis analysis research has been carried out, 16 kinds of current curve template and 73 kinds of pump characteristic curve template have been established using ADO remote data access technology, and the volume efficiency and energy efficiency dynamic control model and chart have been established as well. The production situation analysis using the chart can timely find out the problems existing in the production and puts forward the improvement measures to achieve the purpose of energy saving and consumption reduction.

Abstract: Simulation of nanoscale thermo-fluidic transport has attracted considerable attention in recent years owing to rapid advances in nanoscience and nanotechnology. The three- dimensional molecular dynamics simulations are performed for the system of a liquid layer between two parallel solid walls at different wall temperatures. The solid-solid interaction is modeled by the embedded atom method. The heat flux through the solid-liquid interface is calculated by Green-Kubo method. The effects of interface wettability and wall temperature on the interfacial thermal resistance are also analyzed. It is found that there exist the relatively immobile quasi-crystalline interfacial layers close to each solid wall surface with higher number density and thus higher local thermal conductivity than the corresponding liquid phase. The interfacial thermal resistance length is overestimated by 8.72% to 19.05% for the solid-solid interaction modeled by the Lennard-Jones potential, and underestimated based on heat fluxes calculated by Fourier equation.