共查询到20条相似文献,搜索用时 109 毫秒
1.
用流体力学的三维计算软件,运用湍流脉动动能k方程和湍流脉动动能散耗率ε方程的k-ε双方程模型在给定的数值计算条件下,对板坯连铸结晶器内钢液的流场进行了模拟.通过数值计算,研究了浸入式水口出口面积、水口插入深度、铸坯断面尺寸等工艺参数对结晶器内钢液的流动的影响,为结晶器及水口的优化设计提供了依据. 相似文献
2.
建立了锥阀的三维几何模型,基于RNG K-ε湍流模型,采用SIMPLE算法对两种不同锥角的水压锥阀的三维流场进行了数值模拟分析,总结了不同操作条件下两种锥阀的流场特性。模拟结果显示,锥阀内有明显的双蜗旋流动,出口压力的变化对内部静压力影响显著,而对湍动能的影响则较小。 相似文献
3.
4.
基于Fluent多相流液压滑阀阀芯摩擦力仿真分析 总被引:1,自引:0,他引:1
采用Euler多相流模型、扩展的k-ε湍流模型和SIMPLE算法,基于Fluent软件对滑阀间隙密封内固液两相颗粒湍流进行了数值分析,分析了不同直径和体积浓度的污染颗粒对滑阀阀芯摩擦力的影响。研究结果表明:摩擦力随着颗粒体积浓度增大而近似线性增大;随着颗粒直径的变大,摩擦力先增大后减小,直径与间隙厚度很接近的颗粒即"敏感颗粒",会使阀芯表面产生最大的摩擦力,"敏感颗粒"直径为0.012 mm左右;在液压系统中采用合适尺度的过滤网或过滤芯将"敏感颗粒"附近尺寸的颗粒过滤掉以达到减小阀芯摩擦磨损,提高液压滑阀换向性能,进而提高整个液压系统的使用性能。 相似文献
5.
6.
阀内流道布置对液动力的影响 总被引:1,自引:1,他引:0
本文对滑阀内部不同流道布置情况下的流动过程进行了分析与比较 ,并说明了阀芯上的液动力与阀内的流道布置之间存在着联系 ,通过改变流道布置 ,可以明显减少液动力而不显著增加阀的压降 ,从而大幅度改善阀的性能。 相似文献
7.
阀内流道内布置对液动力的影响 总被引:1,自引:0,他引:1
本文对滑阀内部不同流道布置情况下的流动过程进行了分析与比较,并说明了阀芯上的液动力与阀内的流道布置之间存在着联系,通过改变流道布置,可以明显减少液动力而不显著增加阀的压降,从而大幅度改善阀的性能。 相似文献
8.
连铸中间包内三维湍流流动的数值模拟 总被引:11,自引:0,他引:11
连铸中间包的操作条件决定了其内流动现象的复杂性,为此,本文选择两种不同的湍流模型k-ε和LES(Largeeddysimulation),建立了描述连铸中间包内三维湍流流动的数学模型,并实施了数值计算和模型验证,对单流中间包内的流动现象进行了描述,考察了有,无流动控制情况下中间包内的流动特征和湍流模型的合理性,结果表明,合理的流动控制有利于中间包内非金属夹杂的上浮和吸附,用k-ε模型基本上能够描述 相似文献
9.
10.
11.
磁流变液阻尼器阻尼通道内部磁流变液运动时塞流区边界位置与输出阻尼力之间存在着密切联系。为了得到塞流区边界位置的具体数值和变化规律,基于RD-8041-1型磁流变液阻尼器,对阻尼通道内部磁流变液的剪切应力和流动状态进行了分析,并得到了塞流区边界位置与活塞运动速度之间的函数关系。为了验证所得函数关系的正确性,在推导出磁流变液阻尼器输出阻尼力数学表达式的基础上,根据塞流区边界位置与活塞速度之间的函数关系得到了磁流变液阻尼器在输入电流为1 A时的输出阻尼力,并将计算得到的阻尼力与实际试验测试值进行了对比。对比结果表明:根据塞流区边界位置与活塞速度之间的函数关系计算得到的阻尼力与实测值保持了一致,从而验证了塞流区边界位置与活塞速度之间函数关系的正确性。 相似文献
12.
CuZnSnSi合金钎料在钎焊钢工件中具有良好的综合性能.为进一步探究其合金性能,借助差示扫描分析(DSC)和热重分析(TG)技术,分别采用微分非等温法和积分非等温法分析了CuZnSnSi合金钎料相变过程的热分析动力学.结果表明,CuZnSnSi合金的相变温度范围为1150.5~1221.5 K,吸热峰温度为1174.46 K,在相变过程中没有化学反应,但出现升温段的吸热峰温度滞后于降温段的放热峰,说明了合金钎料在结晶过程需要一定的过冷度;非等温分析法计算得到合金钎料相变表观活化能为615.72 kJ/mol;由Arrhenius公式得出合金钎料相变速率常数k的变化规律为1.71×1027exp(-6.16×105/RT). 相似文献
13.
0IntroductionIn arc welding processes,final microstructure andmechanical properties of the weldments mainly depend onthe thermal cycle undergoing during the heating and cool-ing process.The accurate analysis of the welding thermalprocess is the foundation… 相似文献
14.
激光熔覆熔池二维准稳态流场及温度场的数值模拟 总被引:4,自引:0,他引:4
本文建立了二维准稳态激光熔覆熔池流场及温度场的数值模型,除考虑对流换热外,模型还考虑了局部大变形自由表面.在贴体正交曲线坐标系下采用了非交错网格SIMPLE算法离散求解动量方程,计算出了激光熔覆熔池自由表面形状和温度场、速度场及局部特征凝团参.数值结果表明,表面张力温度系数和扫描速度μ0对熔池自由表面形状及熔池内温度分布、速度分布有重要影响.同时进行激光熔覆的工艺实验,实测枝晶二次臂间距(SDAD)的实验结果和数值结果吻合良好. 相似文献
15.
建立了全位置TIG焊接中平焊、45°下向焊、立焊下向焊的熔池温度场、流场数值计算模型,计算了不同焊接位置以及不同重力加速度值情况下熔池的温度场和流场,分析了重力方向和大小对熔池内流场和温度场的影响规律;发现重力方向对熔池内液态金属的流场、温度场影响明显,液态金属的流动影响温度场分布明显,重力大小对熔池流场的分布形态没有影响,但是对流动速度影响明显. 得到的结论对于研究熔池失稳判定依据、指导设计全位置TIG焊乃至MAG焊工艺具有一定的参考价值. 相似文献
16.
Ki-Su Lee Won-Oh Yang Young-Geun Park Kyung-Woo Yi 《Metals and Materials International》2000,6(5):461-466
A numerical study for analyzing both fluid flow and mixing behavior in gas-stirred ladles with a submerged lance was performed.
At first, the shape and volume of the plumes generated by the submerged nozzle were calculated. Subsequently, the fluid flow
driven by these plumes, and the mass transfer in the ladle were calculated by a three dimensional turbulent simulation program.
Water model experiments for the velocity measurements were performed to verify the accuracy of the calculation results. It
was shown that as the gas flow rate increases, the downward velocity at the ladle wall increases and mixing time decreases.
Mixing time is sensitive to the alloy addition position especially at a lower gas flow rate. The result suggested that the
alloy should be added at the plume zone close to the center at the melt surface 相似文献
17.
拉速对薄板坯连铸过程中流场、温度场及溶质偏析的影响 总被引:1,自引:0,他引:1
针对薄板坯连铸过程中的动量传输、热量传输及溶质传输过程,建立了一个三维三场耦合数学模型。模拟计算了薄板坯连铸过程中的紊流速度场、温度场及溶质场分布,计算分析了拉速变化对三场及凝固过程的影响。结果表明,提高拉速显著增强了铸坯内钢液的紊流流动,改变了温度场形状及溶质浓度的分布。提高拉速导致铸坯上表面钢液流速加快,增加了弯月面的波动,使得射流对窄壁的冲击力变大、凝固坯壳变薄,并有减小溶质偏析的趋势。 相似文献
18.
A three-dimensional (3-D) granular model which simulates fluid flow within solidifying alloys with a globular microstructure, such as that found in grain refined Al alloys, is presented. The model geometry within a representative volume element (RVE) consists of a set of prismatic triangular elements representing the intergranular liquid channels. The pressure field within the liquid channels is calculated using a finite elements (FEs) method assuming a Poiseuille flow within each channel and flow conservation at triple lines. The fluid flow is induced by solidification shrinkage and openings at grain boundaries due to deformation of the coherent solid. The granular model predictions are validated against bulk data calculated with averaging techniques. The results show that a fluid flow simulation of globular semi-solid materials is able to reproduce both a map of the 3-D intergranular pressure and the localization of feeding within the mushy zone. A new hot cracking sensitivity coefficient is then proposed. Based on a mass balance performed over a solidifying isothermal volume element, this coefficient accounts for tensile deformation of the semi-solid domain and for the induced intergranular liquid feeding. The fluid flow model is then used to calculate the pressure drop in the mushy zone during the direct chill casting of aluminum alloy billets. The predicted pressure demonstrates that deep in the mushy zone where the permeability is low the local pressure can be significantly lower than the pressure predicted by averaging techniques. 相似文献
19.
20.
A mathematical model describing the bubble driven bath flow in a drained cell with a center sump was presented, which spanned the fluid around half an anode and was developed to simulate the flow fields. The calculated results show reasonable agreement with the experiment. Then the model was developed to a full cell model, and bath flow pattern in the whole cell was predicted and analyzed. The flow pattern variation with the changes of the ACD, anode slope, anode immersion depth and current density, especially the fluid secondary recirculation, was modeled. According to the results, side channel or slots feeding technique was recommended in such a drained cell. 相似文献