圆柱形叶片潜油离心泵流场的三维数值分析

采用CFD方法研究了潜油离心泵的内部流场，讨论分析了3种不同工况下叶轮和导轮的数值计算结果。数值模拟捕捉到了离心泵内部许多不良流动现象，探讨了影响离心泵效率的原因。泵在设计工况有着良好的流动性能，在非设计工况出现了不良流动现象，影响了泵的效率。计算结果还显示：潜油泵叶轮有较好的水力性能，而潜油泵导轮的水力性能是不完善的，效率较低。     

Simulation of air flow in the IEA Annex 20 test room—validation of a simplified model for the nozzle diffuser in isothermal test cases

The modeling of air supply devices has been identified from the International Energy Agency (IEA) Annex 20 project as one of the most important problems in applying computational fluid dynamics (CFD) to predict air flow pattern and air distribution in buildings, and the complicated HESCO nozzle diffuser used in the IEA Annex 20 test room has been proved to be particularly difficult to model. In a previous study, a simplified model for this diffuser was developed and validated against experimental data. It has been shown that this model can yield good prediction for the wall jet flow issued from the diffuser, but whether this model is capable of correctly predicting the global flow pattern in the whole test room was not known. In this paper, the benchmark data of the IEA Annex 20 Test Cases B2 and B3 were used to evaluate the performance of the model for the prediction of the global air flow pattern in the test room. It was demonstrated that this model can predict the air flow pattern in the whole test room for both the Test Cases B2 and B3 with reasonable accuracy. The significance of a velocity correction when comparing the numerical prediction with experimental data obtained using omni-directional anemometers was also discussed.     

不同类型扩压器对离心式压缩机结构振动与辐射噪声影响的试验研究

扩压器是离心压缩机中的重要部件之一,不同类型的扩压器对压缩机的各方面性能影响很大。本文以MCL离心压缩机为研究对象,分别选取了全高叶片扩压器、楔形扩压器、半高叶片扩压器和无叶扩压器4种扩压器,在φ200模型级试验台上,开展了在不同流量下,不同扩压器对压力脉动(PP)、振动和声强影响的试验,获得不同类型的扩压器对结构振动与辐射噪声的影响的结果,选择楔形扩压器更具有优势,为离心压缩机的优化设计打下基础。     

4—72—11通风机扩散器的合理性分析

通过对通风机扩散器回收动能原理的分析，指出合理选择４－７２－１１通风机扩散器参数是至关重要的。     

采用常规条形流场的质子交换膜燃料电池阴极数值模拟(Ⅰ)模型建立

对采用常规条形流场的H₂-Air PEMFCs阴极建立了二维数学模型,模型的控制方程耦合了连续性方程、Darcy方程、电传导方程以及O₂和H₂O的对流-扩散方程,对氧的电化学还原反应过程采用Butler-Volmer方程描述.利用模型计算了阴极扩散层中电流密度、O₂和H₂O浓度、催化层界面上局部电流密度的分布,分析了采用常规条形流场时气体在阴极扩散层中的传递机制及各组分浓度分布的特点.     

污水排海扩散器优化设计

结合上海市污水治理二期工程,介绍排海工程中扩散器水力计算的新方法,通过控制扩散器三通及喷头局部力系数,使各上升管出流量不均匀分配,数学模型计算结果与物理模型实测值非常吻合。     

Effects of diffuser shape and back pressure on the performance of disk MHD generators

The effects of diffuser shape and back pressure on the performance of closed‐cycle disk MHD generators are investigated with two‐dimensional numerical simulations taking account of the boundary layer. The enthalpy extraction ratio decreases and fluctuates periodically with increase in the back pressure. The amplitude of power output fluctuation and the period depend on the volume of the inverse flow region. For the reduced height diffuser, the inverse flow region is suppressed and the fluctuation becomes smaller than that for the constant height diffuser. When operated with a back pressure lower than an optimum value, the diffuser does not work because of reacceleration in the diffuser. For the higher back pressure, on the contrary, the inverse flow region propagates into the MHD channel, then the enthalpy extraction ratio is reduced and the Mach number at the exit of the MHD channel becomes lower than unity. For the optimum back pressure, high enthalpy extraction ratio is achieved and the adiabatic efficiency at the diffuser exit is decreased by several percent from that evaluated at the MHD channel exit. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 11–19, 2000     

A pseudo-phase-equilibrium approach for the calculation of liquid water saturation in the cathode gas diffuser of proton-exchange-membrane fuel cells

The cathode compartment of membrane electrode assembly (MEA) of the proton-exchange-membrane fuel cell (PEMFC) is studied theoretically. A pseudo-phase-equilibrium approach adopting an approximate phase-equilibrium equation, incorporated with the associated equations of gaseous multi-component diffusion, liquid water capillary transport, and surface electrochemical kinetics, well characterizes the performance of cathode electrode under unsaturated feed. The pseudo-phase-equilibrium approach avoids the need of explicit liquid water front tracking so that only a single domain formulation, without consideration of the interior boundary, is required for the simulation. In order to illustrate the capability of the proposed approach, a mathematical model of the cathode compartment of MEA in one-dimension is formulated, in which gas species concentration profiles, liquid water distribution, and liquid water front are calculated. The validity of the pseudo-phase-equilibrium approach is then evaluated over an extensive polarization range under specified operating temperature, pressure, and inlet humidity. The solutions obtained using the pseudo-phase-equilibrium approach and the exact phase-equilibrium equation are compared over a wide range of parameter values. In addition, the influences of important transport parameters such as water transport coefficient, gas diffuser porosity, and absolute liquid permeability are evaluated and discussed.     

光学传感器星上定标漫射板的特性测量

为了考察星上定标漫射板的光学特性及其在航天环境下的稳定性,对其进行了方向半球反射比(DHR)、双向反射比因子(BRF)、双向反射分布函数(BRDF)等反射特性的测量;同时,进行了系列环境模拟试验.结果显示:星上定标漫射板反射率在可见近红外波段可达0.99,光谱差异＜0.01,在短波红外波段达0.95以上;10～60°BRF变化低于0.1, 0～60°BRDF变化＜0.045,其方向特性与光谱、紫外辐照关系不大;漫射板350 nm反射率在120 h等效紫外辐照下的衰变＜3%,其光学特性受原子氧、质子轰击影响甚微,并通过了航天级力学环境试验.试验研究表明:漫射板具备高反射率、光谱平坦性、朗伯性及其在航天环境下的稳定性,能够满足航天应用要求.     

紫外-真空紫外空间遥感仪器漫反射板的研究

紫外-真空紫外遥感仪器采用铝制漫反射板,传统光学研磨的漫反射板不均匀、半球反射率低、漫反射特性很差,这会影响仪器定标精度。本文提出光学研磨+化学磨砂的新工艺与检测方法,并搭建主要测试装置。测试结果表明,新工艺的朗伯余弦辐射特性得到明显改善,在0°与45°入射时归一化曲线接近标准余弦曲线;300nm处半球反射率均匀度从0.77提到到0.98;200-400nm半球反射率平均提高33%;将其应用于紫外-真空紫外遥感仪器上进行了角度响应测试,漫反射特性明显优于美国02年发射的同类仪器SBUV/2。