Effect of Gas Injection on Fluid Flow in Mold

A mathematical and physical model was adopted to compute the fluid flow distribution in case of localgas holdup in mold. The photography was used to show the fluid field. The predicted flow patterns show. reasonableagreement with experiment observations using actual water model.

Drag characteristics of power law fluids on an upstream moving surface

The specific problem to be considered here concerns the boundary layer problem of a non-Newtonian fluid on a flat plate in length, whose surface has a constant velocity opposite in the direction to that of the mainstream with Uw 〉〉 U∞, or alternatively when the plate surface velocity is kept fixed but the stream speed is reduced to zero. A theoretical analysis for a boundary layer flow is made and the self-similar equation is determined. Solutions are presented numerically for special power index and the associated transfer behavior is discussed.

Energy Saving and Emission Reduction Estimations of Electrified Railways in China

基于中华人民共和国的铁路的部的统计中心收集的年度生产数据，我们计算了节省的精力和触电的铁路的 CO2 ，煤烟， SO2 ，公司， NOx 和 CnHm 的直接排放减小，并且在在这个时期期间，年度平均数精力珍视的 1975-2007 .The 结果表演的时期期间分析了他们的动态特征节省是 1.

Suitable Heat Transfer Model for Self-Similar Laminar Boundary Layer in Power Law Fluids

The classical power law non-Newtonian fluids energy boundary layer equation is proved improper to describe the self-similar heat transfer. A theoretical analysis for momentum and energy boundary layer transfer behavior is made and the full similarity heat boundary layer equation is developed, which may be characterized by a power law relationship between shear stress and velocity gradient with the Falkner-Skan equation as a special case. Both analytical and numerical solutions are presented for momentum and energy boundary layer equations by using the similarity transformation and shooting technique and the associated transfer characteristics are discussed.

Momentum and Heat Transfer in Laminar Boundary Layer Behind Shock Wave

Analytical and numerical solutions are established for momentum and energy laminar boundary layer induced by a shock wave. The results indicated that skin friction σ decreases with increasing in velocity ratio ξ(1≤ξ【 6). For each specified ξ(1≤ξ【 6), temperature w(t) increases with increasing of Tw but decreases with Te , and for a range of t ∈[1,ξ], w(t) decreases with the increasing of t. Thermal diffusion increases with increasing of uw but decreases with increasing Ue.

The Initial, Boundary Value Problems for a Class of Generalized Diffusion Equations

The behavior for a class of initial, boundary value problems of generalized diffusion equations was studied utilizing the similarity transformation and shooting technique. Numerical solutions are presented fork(s) = SM exponent M 1.0 to 5.0, and power law parameter N (N = 0.3 to 3.0). The results shown that for each fixed M, the temperature distribution e decreases with increasing in power law parameter N, and for each fixed N, the temperature distribution 6 increases with the decreasing of M.

Six Convective Difference Schemes on Different Grid Systems for Fluid Flow and Heat Transfer with SIMPLE Algorithm

Performance comparisons are composed of two parts: the first part contains the systematically investigation of six difference schemes including CDS, FUDS, HDS, PLDS, SUDS and QUICK for convection terms in numerical fluid flow and heat transfer based on the finite volume method using staggered and Rhie-Chow’s momentum interpolation collocated grids, the second part contains the comparative computations being conducted on Rhie-Chow’s momentum interpolation collocated grid and Thiart’s finite difference scheme based nonstaggered grid. Three 3-D cases that have analytical or benchmark solutions are adopted. For the first part, the results of computations indicate that, all the six schemes have the same numerical accuracy when the diffusion term is predominant. With the increase of convection, the FUDS, HDS and PLDS almost have the same accuracy in two of those grid systems, while the SUDS and QUICK have higher accuracy than the former. The accuracy of CDS is something in between. For the same under-relaxation factors and convergence criterion, the convergence rate of each scheme on those two grid systems are nearly equal with that on the staggered grid being a little bit faster. For QUICK and CDS, smooth, non-oscillating solutions can be obtained even when local Peclet number may be as large as 31.2-31.3. For the second part, it is concluded that simplified collocated grid system is preferable from numerical accuracy, grid Peclet number limit, sensitivity to the underrelaxation factor and the freedom in choosing finite difference scheme for convection term.

Natural^(15)N abundance in soils and plants in relation to N cycling in a rangeland in Inner Mongolia

Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ecosystems.However,relationships between natural 15N abundance and N cycling processes are poorly understood in China.Here,our primary objectives were to(i)examine the effects of grazing at varying levels of intensity on d15N of soils and plants in a semi-arid grassland;(ii)detect the relationships between d15N of soils and four major N cycling processes(i.e.mineralization,nitrification,denitrification and ammonia volatilization);and(iii)determine whether d15N of soils can be used as an indicator of N cycling in this semi-arid grassland.Methods The field experiment was conducted within the long-term(17-year)grazing enclosures in a semi-arid grassland in Inner Mongolia.Five grazing intensities(0.00,1.33,2.67,4.00 and 5.33 sheep ha
1)were designed.d15N values of topsoils(0–10 cm),surface soils(0–2 cm)and plants were measured in 2006.Differences in d15N of soils and plants between the five grazing intensities were examined.Rates of four soil N cycling processes were measured periodically during the 2005 and 2006 growing seasons.The d15N values of topsoils were linked to the four N cycling processes to investigate their relationships.Important Findings The d15N values of topsoils(5.20–5.96&)were substantially higher than the d15N values of plants(2.51–2.93&)and surface soils(1.44–2.92&)regardless of grazing intensities.The 15N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher d15N values in topsoils than in surface soils.In addition,the d15N values of topsoils were positively correlated with the d15N values of both plants and surface soils.Grazing,especially the high-intensity grazing(5.33 sheep ha
1),resulted in a significant decrease in d15N of surface soils.However,no statistically significant variations in d15N of topsoils and plants were found in response to grazing.The d15N values of topsoils exhibited significant dependence on the cumulative rates of NH3 volatilization,net nitrification and denitrification in 2005 but not in 2006.

Effect of electromagnetic swirling flow in slide-gate SEN on flow field in square billet continuous casting mold

In order to weaken the bias flow in the submerged entry nozzle （SEN） with slide- gate, the rotating magnetic field was imposed. The numerical method was employed to investigate the effect of rotating magnetic field on the flow field in the SEN and the mold under different slide-gate opening ratios. Numerical results showed that when the slide-gate opening ratio is smaller than 100%, the flow field in the SEN and the mold become asymmetry and there is an obvious circulation under the slide- gate in the SEN. With increasing exciting current, the divergent angle of liquid steel at the SEN outlet increases, the impact depth of liquid steel in the mold decreases. With increasing slide-gate opening ratio, the impact depth of liquid steel in the mold increases and the required exciting current to weaken the bias flow should increase.

Effect of Co element on microstructure and mechanical properties of FeCo_x NiCuAl alloys

FeCoxNiCuAl （x values in molar ratio, x=0.2, 0.5, 1, 1.5, 2 and 3） alloys were pre- pared using a suck-casting method. The effect of Co element on phase constituents, microstructure and mechanical properties of the FeCox NiCuA1 alloys was investigated using X-ray diffraction, scanning electron microscopy, optical microscopy and com- pressive tests. It was found that the Co addition has a significant influence on the structure and properties of the FeCo^NiCuA1 alloys. The alloys have typical den- drite microstructure, and are composed of a simple fcc structure and bcc structure. The addition of Co promotes the formation of fcc phase in the alloys, retards the compressive strength and hardness of the alloys, and enhances the plasticity of the alloys.

Similarity Solutions of Momentum and Energy Equations for an Axi-symmetric Laminar Jet

A theoretical analysis for momentum and heat transfer characteristics in a steady narrow axisymmetric laminar jet is made based on the assumption of boundary layer. The types of potential flows necessary for having the similar solutions to boundary layer equations are determined and the analytical solutions are presented for both momentum and energy boundary layer equations. Some transport properties of the jets are