离心泵节能技术工作的改进措施

针对离心泵节能问题,从设计、制造、配套等技术角度进行了阐述分析,提出可通过CAD/CFD技术的应用、传统设计方法的提高和改进、CAM技术在泵制造过程中的应用、提高铸造技术水平、调节转速以及提高离心泵选型的设计水平等措施来实现高效节能的目标。并通过分析目前存在的制约节能工作开展的问题,提出改进离心泵节能工作的实施办法。     

离心风机串联吸气特性的试验研究

离心风机是最常用风机的一种，广泛应用于国民经济的各个领域。为此，在离心风机单机吸气性能试验的基础上，进行了离心风机串联吸气性能试验，得出了串联吸气性能与单机吸气性能的关系，以及适于串联的工况条件，为串联风机的参数选择提供了试验依据。     

改善弯道急流流态的试验研究

在泄水工程布置时，因受地形条件限制，急流弯道往往难以避免。水流进入弯道后将做曲线运动，在离心惯性力和重力的共同作用下，水流流态变得异常复杂。因此弯道急流的改善问题是实际工程中需要解决的具体问题。针对马家岩水库放空洞末端弯道水流情况，结合水工模型试验，提出了在弯道底部设置导流坎和在边壁设置导向翼的两种工程措施，并进行了试验分析比较。两者对减小弯道水面横比降、改善水流流态均有较好效果。特别是改善了弯道出口断面的水舌厚度和流速横向分布的均匀性，保证了末端挑流消能的稳定性和安全性。     

双吸三元扭曲叶片离心泵的造型

双吸三元扭曲叶片离心泵具有叶片形状复杂与多流道等特征,其三维造型涉及问题较多,在泵的三维造型中具有普遍性.为此,以GAMBIT软件为设计平台,结合一个具体的双吸离心泵的造型实例,介绍了双吸离心泵扭曲叶片叶轮和螺旋形蜗壳等部件三维造型的方法,并给出了创建实体模型的详细步骤及三维模型图;此外,还简要说明了在Gambit软件中建模需要注意的问题.     

Quantitative study on solid slag film’s crystallinity of mould fluxes by using DSC method

The method to determine the crystallinity of solid slag film is established by analyzing the DSC curve of solid slag film and corresponding quenched slag. The accuracy of the method is investigated by measurements of prepared samples whose crystallinity is given. In addition, the solid slag films of mold slags used to cast medium carbon steel and low carbon steel are obtained by heat flux simulator in laboratory, and the crystallinity of the two kinds of slag film are also measured by DSC method. Experimental results indicates that the crystallinity of solid slag film can be determined by comparing the crystallization enthalpy of solid slag film and corresponding quenched slag during heating process, and the relative error is within 5.03%. For medium carbon steel, the crystalline fraction of solid slag film is 88.6%, while the crystalline fraction of solid slag film corresponding to low carbon steel is 55.0%. The results are consistent with actual structure of solid slag films.     

平房仓不同风机降温通风对比试验

分别选用两种风机,对高大平房仓进行降温通风对比试验,将两种不同风机降温变化情况进行比较。结果表明,选用轴流风机降温通风,具有耗电低、能耗少、水分损耗低、降温均匀和操作简便等特点,适用于高大平房仓早期降温通风;选用离心风机降温通风,具有降温迅速、操作简便等特点,适用于高大平房仓紧急情况下的降温降水通风。     

Dropwise Condensation Heat Transfer Coefficient on the Horizontal Circular Surface with Radial Gradient Surface Energy

A theoretical model is developed for the dropwise condensation heat transfer on the horizontal circular surface with radial gradient surface energy based on the heat transfer model of individual condensate drop and the size distribution model of condensate drop on homogeneous condensation surface.The effect of variation of contact angle on the gradient surface on condensation heat transfer and condensate drop size distribution is taken account of in this model.The theoretical calculation method was obtained to predict the dropwise condensation heat transfer coefficient on the horizontal circular surface with radial gradient surface energy under various wall subcooled temperature,contact angle profile on wall surface,and working fluid.The effects of surface energy gradient,wall subcooled temperature,and thermophysical properties of condensate on the condensation heat transfer are discussed respectively.The calculation results show that the condensation heat transfer coefficient increases slightly with the increase of wall subcooled temperature.As latent heat and surface tension increasing,the condensation heat transfer coefficient increases.A larger surface energy gradient induces a larger condensation heat transfer coefficient.     

Incentive Mechanism for Team Cooperation Based on Implicit Side Contract

Aiming at the free-riding problem in team incentive, this paper designs a dynamic incentive mechanism based on implicit side contract with dynamic game theory by introducing the reasonable assumption that there is horizontal monitor in team production. The theoretic analysis indicates that the dynamic incentive mechanism, in which a strict group incentive compatibility contract is taken at the first stage and an individual incentive compatibility contract is taken at the second stage, can implement team cooperation uniquely in the general condition of risk aversion and stochastic production by only two stage repeated game.