HLZ直联型立式混流泵在宁夏扬水泵站中的应用

为解决宁夏盐环定扬水工程一泵站在运行中出现的高耗能、出水量不足等问题,将原轴流泵更换为HLZ直联型立式混流泵,分析了HLZ直联型立式混流泵的应用效果及经济效益,达到了泵站改造的效果.总结出,HLZ直联型立式混流泵适应于大流量、扬程10~11 m、前池水位变幅较大的泵站,在提高泵站装置效率、节能、提高经济效益方面有显著效果.     

大型立式水泵机组安装中摆度调整

文章根据驷马山滁河一级站2#机组大修情况,总结大型泵站立式机组安装中摆度调整对策.     

导流板角度对CG型混流泵影响的试验研究

为了减小蜗壳式混流泵内水流因升力作用对蜗壳的斜向冲击,设计加工了3个不同导流板角度的CG型压水室,与比转数n_s=350的混流泵叶轮组合成CG型混流泵,运用试验研究结合理论分析的方法,研究了CG型压水室导流板安放角度对水泵性能曲线的影响。结果表明:导流板角度越小时,泵内液体回流造成的水头损失越小;在低流量处,导流板安放角度越小时,水泵扬程越高;在30°、45°、60°3种导流板安放角中,30°为最优值,导流板安放角为30°时最高效率点处的效率最高。     

立式离心铸造磨球充型过程的影响因素研究

分析了立式离心铸造磨球充型过程的影响因素,并对立式离心铸造型过程的轨迹进行了计算,发现在离心力作用下,无论初始条件何变化,充型过程的轨迹都为近似渐开发,由于初始条件不同轨迹形状和充型时间将发生变化,通过对不同横浇道形状的水模拟得到：近似于离心力场中运动轨这的横浇道形状型腔中的液体量最多,其次是折线形和喇叭形的,长直形的最差。     

X5032A型立式铣床噪声源分析

传动件通常既是噪声源又是振动源。其振动能量可以从机械结构的一部分传至另一部分，并在具有大薄壁的箱体表面上形成声发射，这种声发射现象，在设计实践中常被忽略。本文的实验结果将对此问题进行说明。实践表明，圆锥齿轮副是大多数立式铣床的主要噪声源。     

机械设备安装技术的现状与发展

本文介绍我国机械设备安装技术的过去和现在的情况，论述了现代化机械设备安装技术的主要特点和最新发展。     

混流式喷水推进泵水力设计和性能预报

基于Matlab-Simulink平台开发了一套混流式喷水推进泵参数化水力设计程序,能快速优质完成混流式喷水推进泵设计时轴面投影图绘制、过流面积检查、流网绘制和逐点积分法叶片绘型等环节.采用CFD技术,通过几何建模、网格划分、边界初始和数值计算等步骤实现了对所设计混流式喷水推进泵的扬程、功率、效率和抗汽蚀性能的快速预报...     

Effects of blade rotation angle deviations on mixed-flow pump hydraulic performance

By model test and numerical simulation,this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump.It was found that when some blades had rotation angle deviations,the hydraulic performance curves of the mixed-flow pump would move.With a positive deviation,the curves moved towards the large flow rate;with a negative deviation,the curves moved towards the small flow rate.When some blades had rotation angle deviations,the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased;the larger the deviation,the greater the decrease.When a single blade had a large rotation angle deviation,a rather clear low pressure area was formed,lowering the cavitation performance.When two adjacent blades changed simultaneously,under the small flow rate condition,adverse pressure gradient and flow separation occurred in the flow field,and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly.Near the best efficiency point(BEP),the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage,with an even larger area.Compared to the effect of two adjacent blades,two alternate blades,when changed simultaneously,made the mixed-flow pump slightly less efficient,but with a flatter efficiency curve and relatively wider high efficiency area.By fitting the test results,a functional relation among the BEP of the mixed-flow pump QBEP,the number of deviated blades N,and blade rotation angle deviationαwas established,thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.By model test and numerical simulation,this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump.It was found that when some blades had rotation angle deviations,the hydraulic performance curves of the mixed-flow pump would move.With a positive deviation,the curves moved towards the large flow rate;with a negative deviation,the curves moved towards the small flow rate.When some blades had rotation angle deviations,the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased;the larger the deviation,the greater the decrease.When a single blade had a large rotation angle deviation,a rather clear low pressure area was formed,lowering the cavitation performance.When two adjacent blades changed simultaneously,under the small flow rate condition,adverse pressure gradient and flow separation occurred in the flow field,and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly.Near the best efficiency point(BEP),the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage,with an even larger area.Compared to the effect of two adjacent blades,two alternate blades,when changed simultaneously,made the mixed-flow pump slightly less efficient,but with a flatter efficiency curve and relatively wider high efficiency area.By fitting the test results,a functional relation among the BEP of the mixed-flow pump QBEP,the number of deviated blades N,and blade rotation angle deviationαwas established,thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.     

Multi-objective optimization of a mixed-flow pump impeller using modified NSGA-II algorithm

In order to maintain a uniform distribution of pareto-front solutions, a modified NSGA-II algorithm coupled with a dynamic crowding distance(DCD) method is proposed for the multi-objective optimization of a mixed-flow pump impeller. With the pump meridional section fixed, ten variables along the shroud and hub are selected to control the blade load by using a three-dimensional inverse design method. Hydraulic efficiency, along with impeller head, is applied as an optimization objective; and a radial basis neural network(RBNN) is adopted to approximate the objective function with 82 training samples. Local sensitivity analysis shows that decision variables have different impacts on the optimization objectives. Instead of randomly selecting one solution to implement, a technique for ordering preferences by similarity to ideal solution(TOPSIS) is introduced to select the best compromise solution(BCS) from pareto-front sets. The proposed method is applied to optimize the baseline model, i.e. a mixed- flow waterjet pump whose specific speed is 508 min?1?m3s?1?m. The performance of the waterjet pump was experimentally tested. Compared with the baseline model, the optimized impeller has a better hydraulic efficiency of 92% as well as a higher impeller head at the design operation point. Furthermore, the off-design performance is improved with a wider highefficiency operation range. After optimization, velocity gradients on the suction surface are smoother and flow separations are eliminated at the blade inlet part. Thus, the authors believe the proposed method is helpful for optimizing the mixed-flow pumps.     

Multi-parameter optimization design,numerical simulation and performance test of mixed-flow pump impeller

On the basis of the three-dimensional design platform of the mixed-flow pump impellers, an optimization design system was developed in this paper by improving the genetic algorithm with application of both strategies of keeping the optimal individual and employing the niche. This system took the highest efficiency of the impeller as the optimization objective and employed P, a0 , △θh and △θt , which could directly affect the shape and the position of the blade, as optimization parameters. In addition, loss model was used to obtain fast and accurate prediction of the impeller efficiency. The optimization results illustrated that this system had advantages such as high accuracy and fine convergence, thus to effectively improve the design of the mixed-flow pump impellers. Numerical simulation was applied to determine the internal flow fields of the impeller obtained by optimization design, and to analyze both the relative velocity and the pressure distributions. The test results demonstrated that the mixed flow pump had the highest efficiency of 87.2%, the wide and flat high efficiency operation zone, the relatively wide range of blade angle adjustment, fine cavitation performance and satisfied stability.     

A general alternate loading technique and its applications in the inverse designs of centrifugal and mixed-flow pump impellers

Science China Technological Sciences - For the inverse designs of centrifugal and mixed-flow pump impellers, clarifying the generation process of secondary flows and putting forward corresponding...     

Experimental study of the effect of blade tip clearance and blade angle error on the performance of mixed-flow pump

The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors.The ratio of the mixed-flow pump efficiency reduction and the blade tip clearance variation(η/δ) varies with the flow rate coefficient revealing a parabolic trend.An empirical equation has been developed for the mixed-flow pump model by parabolic fitting.For the same blade tip clearance variation δ,the mixed-flow pump efficiency reduction η increases rapidly as the flow rate rises.For any given flow rate,the efficiency,the head and the shaft power of the mixed-flow pump all decrease with the increase of the blade tip clearance.Among them,the efficiency reduction η varies approximately linearly with the blade tip clearance variation δ.When the angle of an individual blade of the mixed-flow pump has a deviation,the performance curves will move and change.These curves have consistent change directions with the performance curves under the condition of all the blades rotated at the same time,but have smaller offset and lower range of variation.When an individual blade angle error changes to ±2°,the optimal efficiency of the mixed-flow pump will have no significant difference.When the individual blade angle error increases to ±4°,the optimal efficiency will decrease by 1%.     

虚拟现实技术在设备安装中的应用

在当前的RH真空处理精炼炉的设备安装过程中,往往就是对实际设备进行安装和调试, 无法对安装过程进行预演.因此,将虚拟现实和RH真空精炼设备安装相结合,在仿真环境中实现RH真空处理精炼炉的设备安装过程,并对安装过程中出现的问题进行解决,以达到指导实际安装的目的.     

非饱和土诱导减载涵洞的竖向土压力研究

为准确计算诱导减载涵洞的主要荷载,采用圆弧小主应力轨迹描述诱导减载涵洞上方回填土拱效应,以推导考虑土拱效应的滑移面土压力系数表达式,继而基于非饱和土的双应力状态变量强度理论确定滑移面摩擦切应力,建立诱导减载涵洞顶部的竖向土压力解析解,结合等沉面高度求解给出应用步骤,最后对比文献现场实测进行正确性和适用性验证,并定义减载率分析基质吸力及分布形式、吸力角、减载材料厚度和变形模量等因素的影响特性。结果表明：所得涵顶竖向土压力解析解可合理反映基质吸力及分布形式、土拱效应、减载材料性能和等沉面高度的综合影响,完善了诱导减载涵洞设计理论;非饱和土强度提升使摩擦作用增强与等沉面下降同时发生,基质吸力和吸力角对减载率具有双重影响,表现为减载率均先增大后减小,且均布吸力下双重影响更为明显;减载率随减载材料厚度增加而非线性增大并趋于稳定,但随减载材料变形模量增加非线性减小。     

电动机微机式综合保护装置

详细阐述了电动机微机式综合保护装置的构成及工作原理,并对装置硬件和保护软件作了说明,应用实践表明,该装置比集成电路式保护装置有更大的优势.