APPLICATION OF QUADRATIC AND CUBIC TURBULENCE MODELS ON CAVITATING FLOWS AROUND SUBMERGED OBJECTS

Quadratic and cubic Non-Linear Eddy-Viscosity Models(NLEVMs) at low Reynolds number correction were introduced into the present Computational Fluid Dynamics(CFD) framework,to provide better numerical treatment about the anisotropic turbulence stress in cavitating flows,which have large density ratio and large-scaled swirling flow structures.The applications of these NLEVMs were carried out through a self-developed cavitation code,coupled with a cavitation model based on the transport equation of liquid phase.These NLEVMs were firstly validated by the benchmark of disk supercavity,and found able to obtain more accurate capture of the hydrodynamic properties than the linear models.One of such models was further applied on the cavitation problem of submerged vehicles.Ultimately,the supercavitating flows around an especially designed underwater vehicle were predicted using the cubic turbulence model,and its cavitation behaviors were studied.     

淹没扩散出流不稳定现象研究

抽水蓄能电站上水库的进出水口,在抽水工况下,各个水平分流孔口的出流类似于矩形扩散管嘴的淹没出流。针对国内某一在建的抽水蓄能电站上库进出水口的模型试验;采用先进的量测手段,获得了大量进出水口拦污栅处的三维流速资料,发现出水口的水流流态是不稳定的,除随机的脉动外还存在不稳定的摆动:对各流速分量进行了频谱分析和相关性分析,得出各分量的摆动频率和脉动频率及其互相关系数。研究成果可作为进出水口拦污栅设计的参考。     

连铸中间包水口堵塞问题浅析

研究了浸入式水口堵塞的形成机理。堵塞沉积主要是由于氧化物颗粒附着到浸入式水口耐火材料的内表面，继而烧结在一起所致。小沉积颗粒的烧结形成不规则的网状物。耐火材料和钢水问反应层的形成，尤其是当耐火材料中含二氧化硅可还原组分，则加速沉积。另外，采取改善水口材质、改善和维护水口形状、提高钢水清洁度、对钢水夹杂物进行变性处理等措施，可有效防止水口堵塞。     

Influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds

The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.     

矿热炉参数计算的探讨

从传统的电炉参数计算公式出发，推导出符合实际的新参数计算方法，新方法大大减少了传统选择电炉参数的随意性，与实际紧密结合，可以有预见地设计和优化电炉参数，从而使电炉参数达到最佳的冶炼效果。     

用Monte Carlo法模拟矿热炉炉料的导电行为

介绍了Monte Carh，法模拟矿热炉炉料导电行为的初步研究。模拟结果表明，模拟炉料中，矿石粒径一定，随焦炭粒径增大，形成逾渗结构的临界值Φc（导电相体积分数）增大；在临界点以上，炉料导电性与导电相——焦炭含量的关系近似于对数关系。纯焦炭颗粒直径对其电阻影响的模拟结果与冷态实验结果不符，说明该数学模型在模拟炉料电阻变化方面尚需要改进。     

山西省万家寨引黄工程联接段设计特点

从取水枢纽进水塔采用分层取水、输水线路采用PCCP管道输水、调节流量和消能采用淹没式多喷孔套筒阀、对全断面掘进技术的改进等国际先进技术论述了万家寨引黄工程联接段的设计特点,可供类似工程借鉴。     

软开关逆变埋弧焊电源的研究

提出了一种新的相移软开关电路拓扑方案 ,解决了相移软开关电路在空载时超前臂与滞后臂的换流问题 ,并将这种电路形式应用在大功率埋弧焊电源上 ,降低了开关管的开关应力 ,提高了整机的可靠性 .控制方式采用峰值电流反馈控制方案 ,抑制了变压器的偏磁 ,解决了双路逆变器的并联均流问题 .通过研究环流产生的原因 ,提出了一种环流判定的方法以及相应的保护措施 ,可有效地保护主变压器的绕组 .此方案已在逆变埋弧焊系列产品上推广应用 .     

起重机拼板不清根高效焊接及接头性能分析

为了解决拼板在焊接过程中的碳弧气刨清根、板材翻身导致焊接工序复杂、生产效率低下以及无法实行自动化焊接等问题,提出一种采用埋弧焊单面焊加陶瓷衬垫方法,板单元正面进行埋弧焊接,试板背面与陶瓷衬垫紧密贴合,从而实现拼板对接单面焊双面成形.研究结果表明,该埋弧焊接工艺满足100%RT和100%UT探伤,-20℃条件下冲击吸收功高于27 J,其力学性能结果符合标准要求.与传统工艺相比,该焊接工艺在保证其焊接质量的同时可简化生产工序,提高生产效率,降低生产成本,减少环境污染,实现绿色生产.     

小板坯连铸机浸入式水口结构优化的模拟研究

采用物理模拟方法,以鞍钢第二炼钢厂小板坯连铸机为原型,进行浸入式水口结构参数优化实验,得到了适合鞍钢第二炼钢厂生产需要的浸入式水口结构参数,并分析了浸入式水口的结构参数对结晶器内钢液流动状况的影响。