高速气流加速下雾粒的传质

针对高分散气雾两相流动体系,提出了一种新的传质理论表达式,其传质系数用Kolmogoroff长度时间尺度进行关联,并开发出基于Monte Carlo和CFD的联合模拟方案.运用该传质表达式和模拟方案,成功地模拟了氢氧化钠与二氧化碳的气雾两相射流中和反应体系.结果表明相间传质时间尺度(1.6×10-4 s)远小于弛豫时间尺度(4.5×10-4 s),进一步研究说明尽管气雾相间传质的速率很快,但相间传递量是主要通过速度滑移实现的,相间传质对雾粒相的运动行为影响甚小,因而在工程上对于雾粒相运动行为的描述可以忽略传质的影响.由激光多普勒测速仪得到的实验数据证实了模拟结果,表明模拟能正确预测此类输运现象.     

电弧波形与气体保护焊熔滴过渡模式关系研究

利用焊接质量分析仪采集气体保护焊焊接过程中瞬时电流和电压波形特征，利用此波形特征能够定性指出熔滴过渡模式，从而实现在线监测和控制金属熔滴的过渡模式，实现良好的焊接工艺参数。     

液滴旋转模型在重力场和均匀流场中的应用

本文主要应用单液滴旋转模型,研究了重力分离空间均匀蒸汽流场中液滴行为,定性描述了均匀蒸汽流场中液滴轨迹,分析了液滴在重力场和均匀蒸汽流场中运动的影响因素。主要讨论了液滴旋转及升力的影响,为液滴旋转模型的定量分析及其应用奠定了基础。     

Solvent Extraction Calculation Model for Purex Process in Pulsed Sieve Plate Column

A new calculation code PULCO has been developed to simulate the Purex extraction process in a pulsed column. The model for the PULCO code is based on the mass transfer taking place at the interface between dispersed drops and continuous phase fluid. The following physical quantities of the moving drop are included in the model for each period of drop motion in a pulsed column:

1. Mass transfer coefficient from liquid drop to continuous phase

2. Diameter and velocity of moving drop in the pulsed column

3. Holdup of dispersed and continuous phases in the pulsed column

4. Longitudinal dispersion coefficient in the pulsed column.

To establish the validity of the PULCO code, experiments were performed using a 50 mm diameter pulsed column which had a sieve plate section height of 2 m and plates spaced 50 mm apart. The experiments were performed by CY tests with use of unirradiated U and Pu. The experimental concentration profiles fitted well with the calculated concentration profiles.     

波型板分离器竖直板壁水膜流动研究

波型板分离器板壁的水膜流动特性影响分离器内二次水滴的生成．采用数值方法对波型板分离器板壁水膜流动特性进行研究,通过分析波型板板壁水膜流动的特点,并对流动水膜进行合理的假设和简化,建立了波型板板壁水膜流动的物理模型和数学模型。采用有限容积法．对流项采用二阶迎风格式,扩散项采用中心差分格式,对控制方程进行离散,采用ADI（Alternating—Direction Implicit）方法对离散方程进行求解数值研究得出在主流汽体横掠波型板汽水分离器竖直板壁情况下,板壁水膜厚度、平均速度等参数与汽流流动速度和沉降率之间的关系。     

喷淋液滴在空气环境下的运动特性

本文以喷淋液滴在空气环境下运动特性为工程背景,建立单个液滴在常温、常压空气环境中的动量方程,分析液滴沉降特性、追赶特性及运动轨迹行为。计算结果表明,不同喷淋液滴初始条件下,短时间内存在重力大于曳力和重力小于曳力两种情况,但最终减速液滴均会达到受力平衡状态;液滴离开喷淋头后,垂向位移均迅速增大,液滴粒径越大、初始速度越大,垂向位移增长的速率也越大,达到相同位移的用时越短;液滴尺寸、初始速度相差越大,液滴追赶所用的时间越短,追赶位移越小,液滴尺寸、初始速度越接近,液滴追赶所用的时间越长,追赶位移越大;液滴初始速度越大、初始直径越大、喷射角度越大,横向速度消失越慢,达到的横向位移越大,喷射液滴覆盖的面积也越大。计算结果有助于优化工程实际中喷淋系统的设计与布置。     

ESS温室喷雾器喷雾特性的PDIA检测实验

为研究静电喷雾系统(ESS)温室喷雾器的喷雾特性、荷电喷雾场的空间形态及雾滴的尺寸分布,并为具体的喷雾施药场合选择最佳的雾滴大小,运用Oxford激光粒子图像分析测试系统(PDIA)对气流中群体荷电雾滴流场进行实验研究.选取荷电喷雾场中的不同位置,通过对雾滴的粒谱范围、尺寸分布及发散度的测试与分析,为ESS静电喷雾器在温室内的喷施与操作提供实验依据.研究表明:沿轴向距离喷嘴越远,喷雾发展越充分,荷电雾滴粒径越小、分布越均匀;沿横向雾滴粒径呈中间小两边大的分布状况;雾滴粒径谱范围集中在4.4～31.2 μm之间;相对尺寸范围和发散边界随着喷雾场轴向距离的增大而增大、扩散比基本不随距离变化且保持相对稳定.实验结果表明ESS喷雾器的雾化质量很高,具有优良的综合技术性能.     

微乳液的稳定性及其在制备超细Y2O3中的应用

探讨了CTAB／n—C4H90H／c-C6H12／H2O体系微乳液的稳定性，绘制了该体系的三元和拟三元相图，当CTAB与n—C4H9OH质量比为2：3时有较宽的稳定的W／O微乳液相区，是制备超细Y2O3的理想体系。在该体系稳定区内，通过调整ω，可改变微乳水核半径。Y（NO3）3溶液和草酸溶液在微乳液水核（微反应器）中进行沉淀反应，制备出不同粒径、形貌的超细氧化钇。样品经X射线衍射（XRD）、透射电镜（TEM）表征，结果表明，ω增大，水核半径增大，超细Y2O3的粒径变小，形貌也发生变化。当ω=17时，可制备出粒径为30nm的晶型完好的Y2O3立方晶粒。     

Predictive CFD modeling of whey protein denaturation in skim milk spray drying powder production

A new model of whey protein thermal inactivation has been combined with a CFD model developed for skim milk spray drying. Extensive evaporation and particle formation models were used to calculate particle moisture contents, temperatures and residence times. Calculated parameters were then used as input data for an experimentally developed quality model based on Williams-Landel-Ferry (WLF) equations for inactivation kinetics. The developed quality model was implemented into the CFD code and calculated in parallel to simulations of skim milk droplets evaporation based on the characteristic drying curve approach. The quality model and the simulation procedure were validated by comparison of protein activity levels obtained from the CFD with data obtained from differential scanning calorimetry (DSC) of milk powder samples collected during skim milk spray drying experiments. The simulations for different feed rates fit well with measurement results and show that the loss of whey protein activity is lower at higher feed rates, due to lower temperature fields in this case.     

Amyloid Formation in Nanoliter Droplets

Processes that monitor the nucleation of amyloids and characterize the formation of amyloid fibrils are vital to medicine and pharmacology. In this study, we observe the nucleation and formation of lysozyme amyloid fibrils using a facile microfluidic system to generate nanoliter droplets that can control the flow rate and movement of monomer-in-oil emulsion droplets in a T-junction microchannel. Using a fluorescence assay, we monitor the nucleation and growth process of amyloids based on the volume of droplets. Using the microfluidic system, we demonstrate that the lag phase, which is vital to amyloid nucleation and growth, is reduced at a lower droplet volume. Furthermore, we report a peculiar phenomenon of high amyloid formation at the edge of a bullet-shaped droplet, which is likely due to the high local monomer concentration. Moreover, we discovered that amyloid fibrils synthesized in the nanoliter droplets are shorter and thicker than fibrils synthesized from a bulk solution via the conventional heating method. Herein, a facile procedure to observe and characterize the nucleation and growth of amyloid fibrils using nanoliter droplets is presented, which is beneficial for investigating new features of amyloid fibril formation as an unconventional synthetic method for amyloid fibrils.