一种简单适用的离心叶轮工程测绘和绘型方法

介绍了一种工程上简单适用的离心叶轮的测绘方法,该方法简单、便捷、快速,较以往叶轮测绘方法简单、速度快、准确率高;根据叶轮水力设计理论采用方格网保角变换法进行叶轮水力尺寸的绘制,结果表明：通过该方法设计的叶轮,与原测绘叶轮的性能十分接近,完全能满足工程上的应用.     

压缩机叶轮强度设计

介绍了叶轮过盈量和材料对其强度的影响,通过对叶轮过盈量和应力计算以及应力分布云图分析后对叶轮进行了调整。通过叶轮应用分布云图分析,结构调整后的叶轮强度和过盈量满足使用要求。     

叶轮气浮机在含油污水处理中的应用

通过现场中试考察了新型叶轮气浮机的除油和除COD效果,以及用于含油污水处理的可行性.中试试验于2005年11月下旬在炼油事业部污水处理场进行.试验结果表明,叶轮气浮机可以达到与溶气浮选池相近的除油和除COD效果.     

离心压缩机叶轮改造前后的性能分析

对某离心压缩机改造前后的叶轮进行了数值分析.结果表明,改造前后叶轮均满足设计要求,但由于原始叶轮在入口处的相对马赫数较大,所引起的摩擦损失也略大,因此改造后的叶轮性能要好于改造前的叶轮.     

叶轮断裂原因分析与改造措施

通过叶轮断口的宏观分析和微区化学成分能谱分析得出了叶轮断裂的原因,提出了避免叶轮断裂的方法,并对叶轮的制造提出了建设性的意见。     

倒伞型表面曝气机充氧特性研究

为了研究倒伞型表面曝气机动力效率的最佳值,通过改变叶轮的转速和浸没深度,使表面曝气机电机负荷率分别为100%、90%、80%,测试了对应条件下的动力效率。结果表明:表面曝气机动力效率与叶轮转速、叶轮浸没深度、电机负荷都呈抛物线关系;当电机负荷达100%,叶轮浸没深度为-20 mm时,动力效率的最大值为2.099 kg/(kW.h)。     

叶轮断裂原因分析与改造措施

通过叶轮断口的宏观分析和微区化学成分能谱分析得出了叶轮断裂的原因,提出了避免叶轮断裂的方法,并对叶轮的制造提出了建设性的意见。     

M7-29NO13型煤粉离心风机的改造实践

通过分析M7-29N013型煤粉离心机的磨损情况及磨损原因,对风机叶轮叶片、蜗壳及进风口结构进行了相应改造.改造后风机叶轮磨损均匀,风机大修周期由一年延长到两年,既节省了检修费用,又提高了磷肥的产量.     

叶轮生物膜反应器的研制与应用

针对河流水污染治理的特殊性,研制出叶轮生物膜反应器,其工作原理是河流污水流入叶轮生物膜反应器,在驱动叶轮转动的同时,和叶片上的生物膜接触,通过有机营养物的吸附,氧向生物膜内部的扩散以及在膜中所发生的生物氧化等作用,降解水中的污染物,辅以中心轴曝气,强化了污水处理效果.启动流速计算结果表明,反应器启动流速较小.河流污水模拟试验显示出其有较好的污水处理效果.     

基于振动特性分析的离心叶轮结构优化

以某离心叶轮为例,采用有限元法对叶轮进行了强度和振动特性分析,结合参考资料中的理论,找出叶轮结构设计不足之处,对其进行结构改进优化,不仅可以满足叶轮静强度设计的需要,而且优化后的叶轮具备良好的振动特性,为结构设计提供设计参考.     

组合桨的气液搅拌特性实验研究

对 6种三层组合搅拌桨的功率准数及传质特性进行了实验研究。结果表明 ,1层径流型桨叶和2层混流型桨叶的组合 ,综合性能优于其他形式搅拌桨的组合 ,其功率准数比六直叶圆盘涡轮式桨叶减少 4 0 % ,且在通气下其功率下降最小 ,而传质系数Kla与最大的三层六直叶圆盘涡轮搅拌桨相当     

卧式搅拌釜气液传质性能研究

在 50L卧式搅拌釜内,采用氧电极法测量纯水 O2 体系的液侧容积传质系数kLa, 研究搅拌弗鲁德数Fr、桨叶尺寸和液含量等对kLa的影响。随着Fr提高,kLa增大;桨径、桨宽、叶片数和层间距与kLa有关系,而层间夹角对kLa影响不大;随液含量的增加kLa先缓慢升高而后降低,且峰形和峰值随Fr的增大而发生变化。研究结果可供四氟乙烯等聚合釜搅拌桨设计优化和工程放大参考。     

搅拌槽中高粘度液体的传热研究

本文应用内外螺带-锚、双螺带-锚及螺带-螺旋轴-锚三种组合桨,研究了牛顿流体及假塑性流体,在层流域及过渡流域的传热关联式。分别获得了三种组合桨的传热膜系数关联式。为了得到三种组合桨的传热膜系数的通用关联式,本文采用了传热膜系数与单位质量功之间的关联。     

螺带桨搅拌槽内给热系数和所需功率的研究

本文详细研讨了螺带桨搅拌槽内给热系数及其与所需功率的关系.研究中使用了4个不同几何尺寸的螺带装以及8种不同稠度的假塑性非牛顿流体和高粘度牛顿流体.结果表明:在雷诺数小于0.1时,试验流体在槽内的给热系数与浆叶几何尺寸有关.通过回归分析法得到了4个对应于各螺带桨的给热系数关联式;雷诺数大于10时,给热系数和搅拌浆几何尺寸无关,从而得出一个适用于不同螺带浆的共同关联式.实验还研究了给热系数和所需搅拌功率的关系,并用多项式回归法得到了整个实验雷诺数范围的传热-搅拌功率关联式.     

搅拌反应器内三种桨型的气、液分散与相际传质特性研究

本文以改进搅拌发酵罐的桨型为目的,对空气-水、空气-亚硫酸钠溶液系统就六平叶、弯叶、箭叶三种圆盘透平桨产生的气泡平均直径、气含率及容量传质系数的变化规律作了较为系统的研究。实验发现:相同单位体积功率、表观气速条件下,三种桨型各自产生的气泡平均直径相差不大;箭叶桨的气含率较低;六平叶圆盘透平桨具有最大的容量传质系数。     

Transitional Mixing of Shear‐Thinning Fluids in Vessels with Multiple Impellers

The mixing efficiency of shear‐thinning fluids was evaluated using carboxymethylcellulose sodium salt (Na‐CMC) aqueous solutions of varying mass concentrations and three types of impellers (Rushton turbine (RT), six‐flat‐blade turbine (FBT), six‐pitched‐down‐blade turbine (PBT)) which were mounted on a common shaft in combinations of three, four, and five impellers. The mixing time proved to be dependent on the number of impellers as well as on the distance between. The Reynolds number has a significant influence on the mixing time for all studied systems. The results of power consumption allowed to choose the impeller system with the best efficiency.     

Solids suspension with up-pumping pitched-blade and high-efficiency impellers

The use of axial-flow impellers in the up-pumping mode has been increasing, but little performance and design information is available. Up-pumping pitched-blade and high-efficiency impellers have been studied in solids suspension applications, and their performance has been compared to and contrasted with that of the more conventional down-pumping mode. Just-suspended speed data has been interpreted in terms of two literature correlations that can be used for design purposes. Just-suspended torque and power requirements are presented, as well as turbulent power number and flow pattern data. In general, the just-suspended torque and power requirements of up-pumping pitched-blade and high-efficiency impellers are substantially higher than those of the down-pumping mode. However, if a large impeller diameter is required to avoid critical speed limitations or to achieve sufficient power inputs at high solids loadings, then up-pumping impellers may be a viable option.     

Effect of impeller type and scale-up on spatial distribution of shear rate in a stirred tank

The main spatial distribution features of shear rate in a stirred tank operated with five different radial and axial flow impellers were presented with particle image velocimetry (PIV) experiments. Not only the average shear rate in the whole tank but also the local value in the vicinity of impeller increases linearly with impeller speed. Furthermore, the shear coefficient (K_s,imp) at the impeller outlet is linearly related to the impeller flow number (N_q) and decreases with the increase of N_q in general at the constant power consumption per unit volume (P_v). During scale-up based on the constant P_v and geometric similarity, CFD results show that the volume-averaged shear rate (γ_avg) for RDT decreases faster than that of other impellers with the impeller tip velocity (U_tip). The novel multi-blade combined (MBC) impeller with the increased height-to-diameter ratio of the stirred tank is able to more effectively improve the distribution uniformity of shear rate at the same P_v after scale-up. These studies provide a data basis for selecting the impeller types and improving the shear rate environment in the large-scale stirred tank.     

Gas-liquid mass transfer studies: The influence of single- and double-impeller configurations in stirred tanks

The influence of impeller structure on the mass transfer characteristics was studied with the steady-state method for gas-liquid volumetric mass transfer coefficient (k _L a). The single-impeller configurations included eight impeller types (three radial flow impellers, four axial flow impellers and one mixed flow impeller), and the doubleimpeller included three configurations (RT+RT, RT+WH _D , WH _D +WH _D ). For single-impeller, the gas-liquid mass transfer rates of radial flow impellers were better than those of axial flow impellers under the same rotation speed and gas flow rate. The mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) of radial flow impellers were also better than that of axial flow impellers. With the same kLa value under a certain gas flow rate, the local bubble size distribution between radial flow impeller and axial flow impeller was similar. As for double impellers, RT+RT provided the highest mass transfer rate under certain rotation speed and gas flow rate, while WH _D +WH _D gave the highest values of gas-liquid mass transfer coefficient with the same power consumption.     

Axial thrust of axial flow impellers

This paper presents an analysis of the axial thrust of axial flow high-speed impellers under a turbulent regime of flow of an agitated liquid. The axial thrust is calculated from the measured total axial force affecting the cylindrical fully baffled mixing vessel and from the radial profile of the axial component of the ensemble-averaged mean velocity in the impeller discharge stream. The results of experimentally determined values of the dimensionless criteria (thrust number and momentum number) are successfully compared with the axial thrust of the pitched blade impellers calculated from the theoretically predicted simplified radial profiles of the axial component of the mean velocity in the impeller discharge stream.