一种燃气轮机气体燃料调节阀的流动特性分析

针对国内燃气轮机的气体燃料调节阀长期依赖国外进口、缺乏自主设计及验证能力的问题，采用 CFD方法对燃气轮机气体燃料调节阀的流动特性进行了分析。在分析研究时采用实际使用的天然气，获得 了燃料阀相对升程-流量系数和提升力系数曲线，为燃料阀的设计及其控制系统动态特性的研究提供了依据 以及理论基础。     

上下游结构对喷嘴调节给水泵汽轮机调节阀组流动特性的影响

针对某喷嘴调节给水泵汽轮机调节阀组在额定工况时的三维蒸汽流动,采用计算流体力学方法对其进行数值模拟分析,以获取各调节阀均全开时阀组上下游结构对阀组管道内部稳态蒸汽流场的影响.计算中采用剪切应力输运模型(SST)来封闭湍流模型控制方程组,并采用多重参考坐标系法(MRF)计算获取调节级内动叶排通道区域的三维蒸汽流场.重点分析了各阀门通道内的压力损失水平、流量分配情况和过热蒸汽在调节阀组系统中的流动特性,以及多阀腔室、阀门出口下游扩压管路和弯管等部件内部的复杂三维流动特征.结果表明:调节阀流量主要由阀门下游喷嘴数量决定;调节阀距离阀组系统进口的距离对调节阀通流能力具有较大影响.     

多级降压调节阀结构改进与两相流模拟

针对传统串级式降压阀芯加工难度大的问题,提出了一种改进的多级降压阀芯结构,并通过流量试验得到结构改进后的流量控制范围和流量特性。基于FLUENT软件提供的标准k-ε湍流模型和欧拉模型,对改进后的多级降压调节阀进行气液两相流模拟,分析进口气相体积分数对其流量系数和流量特性的影响。结果表明：改进后的多级降压调节阀可拥有不同的流量调节范围;当阀内处于气液两相流状态时,会在各级降压区域内形成气囊,减小调节阀在各开度下的流量系数,但仍能保持等百分比流量特性。     

柴油机可调两级增压系统调节阀流量特性

利用GT-Power仿真软件建立两级增压系统WP7柴油机仿真模型,研究不同流量特性调节阀在可调两级增压系统中的工作性能,获得两级增压系统调节特性;比较不同调节阀流量特性对增压压力调节的影响,分析不同流量特性的阀门开度对增压压力有效调节范围以及全开度范围单位调节量变化规律。结果表明:不同流量特性调节阀对可调两级增压系统调节特性不同,直线型、快开型和抛物线型流量特性调节阀对增压压力的有效调节开度相对较小,可以实现对增压压力的快速调节;等百分比流量特性在全开度范围内单位调节量基本相同,在小开度下能够降低流量敏感性、提高控制精度,大开度下提升流量敏感性、提高响应快速性,可以较好地满足两级可调增压系统大跨度、高精度增压压力调节需求。     

高温高压差调节阀研制

高温高压差调节阀广泛应用于电力、石油化工等行业,但目前还主要依赖于进口。本文依据两相临界流理论,初步揭示了调节阀中高温高压流体流动及蒸发的基本规律,进行了调节阀的方案及结构设计。并在动力工程多相流国家实验室高压汽水两相流实验台上进行了实验。结果表明,对于高压饱和水流过调节阀,阀门背压均能有效地降低到1.0MPa以下,流量主要取决于面积最小级的通道面积,随入口压力、阀杆调节开度增大,流量增大。实验表明调节阀的研制是成功的。     

一种新型调节阀结构介绍及流场分析

调节阀在汽轮机流道结构的入口流量控制中起重要作用。随着汽轮机效率的不断提高,对调节阀效率的要求也越来越高。但现有调节阀在使用中存在很多流动问题,如阀头边界层分离、肾型涡结构与阀头后高湍动能区等。这些因素对进一步提高调节阀的流动效率提出了挑战。本文从阀头和阀座的结构分析入手,研究调节阀的内部流动特性,找出影响调节阀流动效率的关键因素。新型调节阀的计算结果表明,改进后的调节阀结构使得阀通道内的流动状态得到有效改善,调节阀的全压损失系数明显下降。     

超临界600MW汽轮机调节阀流场三维定常数值模拟研究

分析了超临界600MW汽轮机调节阀阀腔进口、阀腔顶端、阀座进口、阀座收缩段、阀座喉部、阀座渐扩段、阀座出口、阀碟等关键部位分别在调节阀（GV）的100％、50％和30％开度下的流动特性。     

循环流化床锅炉控制系统优化

为解决某厂2台310 t/h循环流化床锅炉控制系统一直无法投入自动的问题,结合该厂蒸汽负荷频繁波动的运行特点,在确定燃料、一次风、二次风静态关系的基础上,对循环流化床锅炉进行了蒸汽流量、燃料、一次风、二次风的扰动试验.通过分析得到母管压力、床温等参数的动态响应特性,确定了压力控制燃料、氧量修正控制二次风、床温修正一次和二次风配比的控制方案,并设计了多输出控制系统的自动平衡回路.采用新的控制策略后,无论是在外负荷扰动还是在锅炉燃料扰动下,极大程度上保证了系统的稳定性和可靠性.     

双燃料发动机电液协同控制天然气喷射阀运动特性研究

研究了天然气/柴油双燃料发动机电液协同控制燃气喷射阀的运动特性,确定了影响喷射运动特性的主要因素,掌握了喷射阀喷射规律,并通过装机试验分析了喷射阀的适用性。研究结果表明:泄油口孔径一定时,喷射阀最大升程受液压活塞泄油孔位置影响,控制脉宽越大,喷射阀喷射持续时间越长,进气量越大;在喷射阀结构一定的情况下,液压压力及控制脉宽是影响喷射阀运动特性的重要因素,增大液压压力可以增加喷射阀启动及回落响应性,同时也会增大喷射阀的进气流量。     

高压共轨供油泵进油计量阀的开发研究

分析了高压共轨供油泵进油计量阀的结构及原理,并对进口的几种计量阀样品以及自主开发的计量阀进行了流量特性对比试验.大量的试验及改进表明,自主开发的进油计量阀对轨压控制的稳定性、动态响应性、试验的重复性等达到了设计要求,可满足高压共轨供油泵的配套要求.     

Parametric study on Tesla valve with reverse flow for hydrogen decompression

Recharge mileage is of great importance for a hydrogen fuel cell electric vehicle. High pressure hydrogen storage can increase the recharge mileage significantly. Before hydrogen flows into the fuel cell, a decompression process is necessary. To overcome the seal of the piping system and realize the decompression, Tesla valve can be well used, since it is a type of check valve without moving parts, and when there is a reverse flow, large pressure drop appears between the inlet and outlet. In order to obtain a better pressure drop performance for a Tesla valve, in this paper, the structural parameters including the hydraulic diameter, the valve angle, and the inner curve radius are investigated for a large range of inlet velocities. The results indicate that a small hydraulic diameter and small inner curve radius but large valve angle can provide a higher pressure drop under a large inlet velocity, while the pressure drop under different structural parameters barely changes under a small inlet velocity (less than 100 m/s). Besides, there is a low-pressure zone behind the outlet of the bend channel, which should be paid attention. This work can be referred by the further applications of Tesla valves in hydrogen fuel cell electric vehicles for hydrogen decompression.     

低流阻系数轴流式止回阀的内部流场分析

为了设计公称直径为DN200的低流阻系数轴流式止回阀,并准确分析其压力损失和流阻特性,在其原有的结构基础上,用汇源法设计止回阀的阀芯结构,得到结构优化后的轴流式止回阀。基于FLUENT(商用计算流体力学)软件提供的标准k-ε两方程湍流模型,对结构优化后的轴流式止回阀进行三维流道数值模拟,求解出不同工况下的压力云图和速度流线图,计算出优化后的止回阀流阻系数在0.272以下,小于优化前的0.4。最后,总结出进口压力、进口速度与流阻系数之间的关系。计算结果表明:在止回阀流道结构保持不变的情况下,影响止回阀流阻系数的主要因素是进口平均速度,随着进口流速的增大,止回阀的流阻系数呈逐渐减小的趋势;在进口速度保持不变的情况下,进口压力的变化对止回阀的流阻系数影响较小。     

Performance improvement of a PEMFC system controlling the cathode outlet air flow

This paper presents a stationary and dynamic study of the advantages of using a regulating valve for the cathode outlet flow in combination with the compressor motor voltage as manipulated variables in a fuel cell system. At a given load current, the cathode input and output flowrate determine the cathode pressure and stoichiometry, and consequently determine the oxygen partial pressure, the generated voltage and the compressor power consumption. In order to maintain a high efficiency during operation, the cathode output regulating valve has to be adjusted to the operating conditions, specially marked by the current drawn from the stack. Besides, the appropriate valve manipulation produces an improvement in the transient response of the system. The influence of this input variable is exploited by implementing a predictive control strategy based on dynamic matrix control (DMC), using the compressor voltage and the cathode output regulating valve as manipulated variables. The objectives of this control strategy are to regulate both the fuel cell voltage and oxygen excess ratio in the cathode, and thus, to improve the system performance. All the simulation results have been obtained using the MATLAB-Simulink environment.     

喷油器控制阀空化现象可视化试验与模拟分析

为了获得喷油器控制阀空化现象的直观流动图像,搭建了喷油器控制阀比例放大可视化试验台。采用高速摄像和长工作距离显微成像技术,研究了不同球阀升程和进口压力下控制阀区域空穴两相流动的特性。通过数值模拟的方法对试验得到的流动图像进行了双向验证。研究结果表明:控制阀区域的空化现象主要发生在球体表面、阀座锥面和进油孔处;空化数可以反映控制阀区域空化的强度;控制阀疲劳试验中气蚀环大于密封环的原因是球体表面发生强烈空化的区域比落座撞击区域靠上。     

共轨燃油系统油量调节电控执行器数值模拟与优化设计

以共轨燃油系统油量调节电控执行器为研究对象,运用AMESim软件完成机械、流体、电磁阀的系统建模,开展机械、液压、驱动等方面性能仿真,通过比较分析,得出各因素对性能的影响,总结提出油量调节阀电控执行器的关键设计原则,并利用该方法完成了某型油量调节阀的优化设计。     

New electronically controlled hydrogen-gas injector development and testing

The feasibility of high-pressure hydrogen-gas injection was investigated in a diesel engine with the help of an electronic control under microprocessor management. An injector prototype was developed with variable area orifice fitted with a solenoid actuator for lifting of the needle valve. A metering valve controlled by a digital actuator was installed at the injector's inlet to throttle the gas flow from the cylinder with compressed hydrogen. The injected fuel dose was therefore under double control: by the time of the injector's opening and by the metering valve flow area. This system was first investigated on a test set-up where the pressure in the injector, the needle lift and the gas dose were measured. A concentrated gas discharge rate characteristic of 3 ms duration was obtained. An attempt was also made to measure the gas discharge rate by recording the amplitude of the pressure wave created in a special long pipe. Ignition feasibility tests were finally conducted in a high speed diesel engine with spark ignition support.     

降低车用增压非中冷柴油机有效油耗率的计算研究

以车用涡轮增压非中冷柴油机６１１３２为例，分析了降低该机有效油耗率的方法．利用上海交通大学最新开发的一维非定常流动模拟计算程序ＦＶＭ－ＴＶＤ，分别对提高增压压力、排气支管扩压、变进排气正时、单排气管放气及双排气管放气几种方案进行了计算．计算结果表明：提高增压压力、排气支管扩压２５％、改用双排气管放气可以降低最低有效油耗率３－４ｇ／ｋＷｈ，而原机的进排气正时设计水平较好。可以不用改变。     

降代车用增压非中冷柴油机有效油耗率的计算研究

以车用涡轮增压非中冷柴油机6113Z为例,分析了降低该机有效油效率的方法,利用上海交通大学最新开发的一维非定常流动模拟计算程序FVM-TVD,分别对提高增压压力、排气支管扩压、变进排气正时、单排气管放气及双排气管放气几种方案进行了计算。计算结果表明：提高增压力、排气支管扩压25%、改用双排气管放气可以降低最低有效油耗率3～4g/kWh,而原机的进排气正时设计水平较好,可以不用改变。     

循环流化床锅炉燃烧系统动态特性分析

根据循环流化床锅炉的工作特点以及燃烧系统输入和输出过程变量间的耦合关系,讨论了ＣＦＢＢ的蒸汽压力和床温的动态特性。认为引起蒸汽压力变动的主要原因在于燃料量（内扰）和汽轮机调门的变化（外扰）;而影响床温变化的主要因素是给煤量、风量、物料循环量的变动,并从传热和燃烧过程分析了这些因素间的相互耦合关系。这对ＣＦＢＢ燃烧自动控制系统的设计与调试,以及整个控制系统的可靠运行都至关重要。     

Experimental analysis of an ejector for anode recirculation in a 10 kW polymer electrolyte membrane fuel cell system

For analyzing ejector's performance in the system, an ejector for a 10 kW polymer electrolyte membrane fuel cell (PEMFC) system was first designed, manufactured, and a 10 kW PEMFC system bench was built up. A proportional valve and PI pressure feedback control method were adopted to control the hydrogen supply and anode inlet pressure. During the test, performances between dead-ended anode (DEA) mode and ejector mode were compared. Ejector's performances in the system, i.e., volume flow recirculated ratio, difference pressure, dynamic responses of primary pressure, anode inlet pressure, and recirculated gas flow rate during the purge process and current variation condition, were investigated. The results show that pressure adjustment is accurate, continuous, and fast using the proportional valve and PI pressure feedback control method. The hydrogen consumption rate in the ejector mode can reduce from 5% to 10% compared with the rate in the DEA mode except for the stack current 5 A and 10 A conditions. For better water removal out of the anode channel in ejector mode, the maximum stack power increases from 5.11 kW (DEA mode) to 9.56 kW (ejector mode). Anode pressure surge caused by the purge valve switching enhances the ejector's recirculated performance significantly.