泵站开敞式进水池水流水力特性研究

针对开敞式进水池水流流态问题建立了相应的概化模型,采用数值模拟方法研究了喇叭管中心与后墙距离、悬空高度和淹没深度对进水池水流特性的影响,从水力学角度提出了泵站开敞式进水池的优化体型和最佳工作水位的概念。研究结果可为泵站设计和泵站技术改造提供理论依据。     

簸萁形进水流道进水收缩段底面倾角对流道水力性能的影响

为了探究簸萁形进水流道进水收缩段底面倾角对流道水力性能的影响,建立了簸萁形进水流道的进水结构物理模型和水动力学模型,采用雷诺N-S方程和RNGκ-ε湍流模型,对进水收缩段5种不同底面倾角的流道水流流场进行数值模拟。结果表明,底面倾角对流道进水收缩段和喉部的流速分布影响较大,较大的底面倾角使进水收缩段的流线分布密集度和喉部流线弯曲度增大、流速升高,增大了流道水力损失,降低了流道出口断面流速分布的均匀度;较小的底面倾角使进水收缩段的流线分布平顺和喉部流线弯曲度变缓、流速降低,减小了流道水力损失,提高了流道出口断面的流速分布均匀度;进水收缩段底面倾角的大小对流道出口断面的水流速度加权平均角无明显影响;分析不同底面倾角的流道水力性能,在簸萁形进水流道的进水收缩段底面倾角≤3°时,进水流道的水流平顺,水力损失小,流道出口的水流流态满足水泵叶轮室进口的进水条件。     

基于CFD的泵站进水池流场水流特性分析

鉴于泵站进水池内的水流条件直接关系到水泵能否正常运行,通过CFD的方法,采用ANSYS 15.0软件模拟了泵站进水池在无隔墩和有隔墩两种体型下的流场,预测了吸水管内涡核的位置,并分析了进水池内的流态、流速分布规律及吸水管内的流速分布规律。结果表明,进水池设置隔墩后,吸水管内的涡核显著减小,属于水下涡第二类即带核物的涡类型;吸水管中心与进水池后壁、侧墙的距离关系到漩涡的产生,在泵站设计中应予以重视;隔墩对调节进水池内的流速分布和改善水流条件具有一定的作用。     

基于CFD的泵站进水池流场水流特性分析

鉴于泵站进水池内的水流条件直接关系到水泵能否正常运行,通过CFD的方法,采用ANSYS 15.0 软件模拟了泵站进水池在无隔墩和有隔墩两种体型下的流场,预测了吸水管内涡核的位置,并分析了进水池内的流态、流速分布规律及吸水管内的流速分布规律。结果表明,进水池设置隔墩后,吸水管内的涡核显著减小,属于水下涡第二类即带核物的涡类型;吸水管中心与进水池后壁、侧墙的距离关系到漩涡的产生,在泵站设计中应予以重视;隔墩对调节进水池内的流速分布和改善水流条件具有一定的作用。     

轴流泵站开敞式进水池的数值模拟与技术改造

以浙江省诸暨轴流泵站为例,基于三维湍流Navier-Stokes控制方程,采用标准κ-ε模型和SIMPLEC算法对轴流泵站进行了数值模拟,分析了开敞式进水池的水流流态和轴流泵叶轮进口断面的轴向流速分布,进而提出了进水池后壁距尺寸优化、管后隔板和后墙隔板3种技术改造方案,并比较了3种技术改造方案下的模拟结果。结果表明,管后隔板为减少该轴流泵站进水池回流的最佳技术改造方案。     

基于RNG湍流模型的泵站进水流道三维数值模拟

运用基于壁面律的RNG k-ε湍流模型对新型空心桩式水泵站进水流道进行数值模拟,采用交错网格的有限体积法求解三维不可压Navier-Stokes方程,提出优化进水流道目标函数并依据数值模拟结果预测进水流道水力损失.根据经验公式计算的水力损失与预测的进水流道水力损失较为接近,表明采用RNG k-ε湍流模型能较好地预测进水流道的水力性能,对进水流道内特性数值模拟和外特性预测研究有较高的推广价值.     

泵房进水流道堵塞对其水力性能的影响

泵房进水流道的水力性能直接关系到泵站的安全、高效运行,结合某核电站工程实际,对泵房进水流道进行物理模型试验,研究了泵房进水流道板框滤网堵塞时的水力性能,揭示了板框滤网堵塞对进水流道流速分布的影响规律。试验结果表明,当板框滤网堵塞时,进水流道1.5 D断面、3.0 D断面、进水池断面的流速分布不均匀度与流速加权平均角度明显减小,流道水头损失增加,流道出现不利流态,影响水泵的安全运行;同时增加进水流道水位能改善流道的水力性能。这为其他泵房的优化设计及安全运行提供了参考依据。     

杏林湾排涝泵站竖井贯流泵装置进出水流道流态的数值分析

运用三维湍流数值模拟方法对杏林湾排涝泵站竖井贯流泵装置进出水流道流态进行数值模拟,分析进水流道的流场均匀度和出水流道的扩散均匀性,提出优化方案。模拟结果表明,优化后的竖井贯流泵装置,在均匀进流的条件下,进水流道内的水流流态较好,竖井两侧流道内的水流流速分布较均匀,未出现明显的漩涡、回流等不良流态,水泵进流均匀、平顺;出水流道通过设置中隔墩的长度,不仅水流流态得到一定改善,而且中隔墩两侧水流流量分配基本均匀,有助于保证泵站良好的出水条件。     

镂空式整流底坎对侧向进水泵站前池流态的影响

为了改善侧向进水泵站进水流态,采用CFX软件对侧向进水泵站前池流态进行了数值模拟,并结合物理模型试验,研究了在前池入口处设置不同孔高比镂空式整流底坎对水流流态的影响。结果表明,在加设七种不同孔高比镂空整流底坎后,流态方面,底坎孔高比为0(无孔整流坎)时,相比不设整流底坎时进水流道前的漩涡区大幅减小,在引河处仍存在低速回流区;镂空式整流底坎设置后,进水前池回流区明显减小,当孔高比达到0.6时,漩涡和回流区基本消失,进入进水池水流无明显偏流,流态相比较好;流速均匀度方面,进口断面轴向流速均匀度随着孔高比的增加先增大后减小,当孔高比为0.6时,进水池入口处流速均匀度达到了74.27%,相比于孔高比为0时提高了6.77%,即当孔高比为0.6时流速均匀度较好。     

杭州三堡泵站进水池复杂流场的三维模拟分析

为了改善杭州三堡泵站进水池中的不良流态,运用成熟的商业数值分析软件,从N-S方程出发,以Realizableκ-ε湍流模型作为预测进水池漩涡核心区位置的手段,模拟分析了进水池在部分运行条件下侧向水流对正向水流较大的扰动,提出了增大侧向水流与正向水流的交汇角、布置导流墩阻隔横向水流的工程整流措施(方案3),从而提高了水泵的运行效率。     

小型锅炉烟尘测试时锅炉出力的计算

锅炉烟尘测试时,必须对锅炉出力进行测试。但监测中,许多小型锅炉往往不具备相关的计量装置和仪表,为解决这一问题,文章提出了用烟气量和空气过剩系数来计算锅炉的出力的公式,在实际使用中,该方法简单易行,其结果和实测值具有很好的一致怀。     

Unerroric of control of mutual compliance of the efficiency of hydrogen engines of unmanned vehicles in the conditions of mass production

The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO₂ and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized.     

中国煤炭地下气化技术的发展

本文综述了煤炭地下汽化技术的国内外发展现状,对我国“长通道、大断面”煤炭地下气化新工艺给予了技术经济评述,并提出了发展煤炭地下汽化技术的政策建议。     

Review of theory of distortion and disintegration of liquid streams

Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined.     

MgO膨胀剂细度对MgO水化和水泥浆体膨胀的影响

基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁（MgO）,研究了该型MgO膨胀剂（MEA）细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析（TG DSC）分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。     

机车车轮多轴疲劳强度安全评定的研究

使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。     

Constructal optimization of the geometry of an array of micro-channels

This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed.     

固体热辐射Yong性能分析

本文对漫灰均温物体在常物性条件下对外辐射传热的Ｙｏｎｇ值计算建立了数学模型。通过与物体内能Ｙｏｎｇ公式的数值计算比较,得出了辐射能量的Ｙｏｎｇ值不大于内能Ｙｏｎｇ值的结论。从初步的热射Ｙｏｎｇ值计算公式发现。Ｙｏｎｇ与物体表面辐射率有关。     

Measurements of concentration distribution of hydrogen jet using deflection of center of the laser spot

The main purpose of this work is to propose a new method to evaluate the concentration distribution of the hydrogen jet by using a He–Ne laser through the jet. This research attempts to apply the expression of concentration Gaussian distribution, the refraction formula of inhomogeneous refractive index medium, and the concentration inversion function to disclose the displacement of the center of the laser spot at different heights in the gas jet. The spot images of the laser beam passing through the gas jet at three vertical heights z = 10d, 20d, 30d, and different radial positions are obtained. The radial spatial asymmetry of the gas jet is also found in the experiment. Finally, the calculated concentration distribution curve and the fluent simulation curve, it is found that the two results are very similar. Our findings show that the error between the concentration distribution of this method and the simulated concentration distribution reaches 2.43%.     

Heat of vaporization of mixtures

General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996