液体射流与空气交叉流动喷雾的数值模拟

采用气相的时均雷诺方程,在拉格朗日框架下求解离散相的运动方程,对水与空气交叉流动的喷雾流场进行了数值模拟研究.湍流模型为标准κ-ε模型,通过在气相方程中添加源项的方法,对两相间存在的质量、动量和能量交换过程进行了模拟;还添加了描述液滴的破碎及其碰撞聚合过程的计算模型;参考实验中的实测入口风速大小,添加用户自定义函数定义气相入口边界风速.计算时,交替求解气相和离散相方程直到两相都达到收敛来实现两相间的双向耦合.并将计算网格分割为两部分,在拥有两个处理器的工作站上并行运行.模拟结果与实验结果的对比显示,喷雾轨迹和液滴粒径大小与实验结果符合较好,也较合理地模拟出了液滴的空间分布情况.

农村剩余劳动力的交叉流动与农村经济的发展

本世纪50年代以来,许多发展经济学家都毫不例外地肯定了人口流动对发展中国家所起的积极作用。中国作为世界上最大的发展中国家,当前人口流动的范围速度都是绝无仅有的,我们应当充分肯定人口流动积极作用的同时,也要对我国人口盲目流动带来的消极影响加以分析,从而制订出我国人口流动的相关政策。

交叉流动换热在热管换热器中的应用

在热管换热器中,当冷热两股流体流量相差甚远时,采用两股流体交叉流动进行热交换,比传统的逆流换热有很多明显的优势。尽管换热器的体积和重量不会有明显的差别,但换热系数可提高56%,加热侧受热面减少35.8%,热管数量减少35.8%,烟气流动阻力减少50%,从而使制造成本下降5%～10%。

提高静压轴承性能的全交叉流动技术

RHP 轴承公司新研制了一种全交叉流动静压轴承(TCF)。该轴承的设计,使在凹槽内的垫片和齿状或槽状的环形面具有新的结构特性。凹槽内垫片的设计(图2),可促使油围绕垫片流动,因而减少了压力梯度;而槽状环形面则可以减少在高速运行时伴有湍流的流体动力效应。虽然大部分有害的湍流流体动力效应如充气及流体惯量已大量减少,但是仍不能全部消除。TCF 轴颈轴承的全面试验。

对向流动交叉换热式合成塔的特点及应用

介绍了对向流动交叉换热式氨合成塔内件的结构、特点及实际生产中的应用情况。

热空气式加湿除湿海水淡化装置研究

基于喷淋水自循环与太阳能加热空气的方法,设计一种加湿除湿型海水淡化装置。首先对装置的结构及原理进行说明,然后对装置各部分的能量平衡进行分析,最后实验研究装置集热及产水性能。从实验结果可知,淡化装置所匹配的太阳能空气集热器效率在37%~50%之间,在循环风量为164.21 m^(3)/h、海水喷淋速率为971 kg/h以及淡水喷淋速率为896 kg/h的条件下,装置最大半小时产水量为2.2 kg。此外,研究结果显示,因喷淋水自循环,喷淋速率的变化对装置产水量的影响较小。

Bubble Formation Characteristics from a Sieve Tray with Liquid Cross-flow

An apparatus,desinged to simulate bubbling of a sieve tray operated in froth regime,was employed. Bubble contact angles in and above the incipient weeping regimer for an air-water-plexiglas system were investigated. The influence of both liquid cross-flow and gas up-flow upon bubble contact angles was examined. A model considering the influence of liquid cross-flow was developed to predict bubble size from a sieve hole in froth operation regime.The comparison shows that the bubble sizes predicted by the present model are consistent with our experimental values and the available published experimental data.

Effect of particle loading on heat transfer enhancement in a gas-solid suspension cross flow

Heat transfer between gas-solid multiphase flow and tubes occurs in many industry processes, such as circulating fluidized bed process, pneumatic conveying process, chemical process, drying process, etc. (This paper focuses on the influence of the presence of particles on the heat transfer between a tube and gas-solid sus-pension. The presence of particles causes positive enhancement of heat transfer in the case of high solid loading ratio, but heat transfer reduction has been found for in the case of very low soliding ratio (Ms of less than 0.05 kg/kg). A usefial correlation ineorpomting solid lolling ratio, particle size and flow Reytmlds number was derived from experimental data. In addition, the κ-ε two-equation model and the Fluctuation-Spectrum-Random-Trajectory Model (FSRT Model) are used to simulate the flow field and heat transit of the gas-phase and the solid-phase, respectively. Through coupling of the two phases the model can predict the local and total heat transfer characteristics of tube in gas-solid cross flow. For the total heat transfer enhancement due to particles loading the model predictions agreed well wih experimental data.

八、其他

000594 连续分解微藻/培养介质的膜技术:交叉流动微滤和超滤=Membranetechnology for the continuous separationmicroalgae/culture medium:compariedperformances of cross-flow microfiltrationand ultrafiltration[刊,英]/Rossignol N,Vandanjon L,Jaouen P...//Aquac.Engin..-1999,20(3).-191～208在许多生物技术应用方面。

户籍登记法规的改革与经济发展的需要

随着对内搞活经济、对外开放形势的发展,我国人口出现了交叉流动:一方面,由于农村广泛推行农业联产责任制,农村生产力获得大解放,农村中剩余劳动力一般占农村人口的30—40％,高的地区达60％。这些剩余劳动力正向城市,尤其是向小城镇流动。另一方面,由于蓬勃发展的乡镇企业和一些中小城市工业急需各类科技人才和有熟练技能的劳动力,通过招聘等渠道。