柴油发电机组安装架结构改进分析

为合理地选择柴油发电机组安装架的结构形式和支承位置,对柴油发电机组安装架在运用中出现的问题进行了分析,并结合安装架的受力特点,提出两种设计方案。为比较两种方案的可行性,采用有限元方法对两种设计方案安装架的强度和刚度进行计算、分析和比较。计算结果表明,两种方案的强度、垂向刚度均能满足设计要求,但方案二的扭转刚度明显优于方案一。     

气门调整盘塑性成形工艺

介绍了气门调整盘锻件的4种塑性成形工艺方案,分析了它们的优缺点,并着重分析了其中两种优化工艺方案模具的设计要点。     

末级中空静叶除湿方法的数值研究

采用数值计算方法对某末级中空静叶片开双抽缝除湿方法进行了研究。通过研究抽吸缝除湿机理设计了两种方案的双抽吸缝结构,计算了一级采用双抽吸缝结构的叶栅流场。比较了两种双抽吸缝方案条件下不同叶高上的流场、湿度场以及叶片表面的压力情况。通过分析得到两种抽吸缝方案的计算结果,得到了两种双抽吸缝中占优的方案。     

车轮与试验台滚轮对中方案研究

车轮与滚轮的对中是铁道车辆滚动试验台进行试验的前提。研究了两种测量机构方案,建立了对中的测量仪器模型,对两种测量方案进行了误差分析和对比。     

发动机齿轮传动机构激励载荷分析研究

针对某柴油机齿轮传动机构两种不同结构布置方案,对各对齿轮副之间的啮合冲击力进行了分析研究,得到了齿轮副之间的激励载荷水平,并将两种设计方案在工作中产生的激励载荷进行对比分析,分析表明,新方案的激励载荷水平明显优化于原方案,为工程设计的方案选择提供了充足的依据。     

南京某车间中央空调方案选择的理论分析

结合南京某车间中央空调方案选择的实例,计算两种空调系统的能耗,并对两种系统进行了经济性比较分析,为工程方案选择提供理论依据和参考。     

供热系统完善化改造方案比较及分析

分析阜新发电厂目前供热情况和不能满足供热需求的原因,在考虑现有设备和以后的发展情况,提出了两种方案并对两种方案进行比较.     

光伏电站直流线损的两种测量方法对比分析

针对光伏电站直流线损进行了实验测量,测量过程中分别使用了两种方案,即直接测量功率的方案和通过测量电压电流来计算直流线损的方案。对两种方案的测量结果进行了对比和分析。结论表明,通过测量电压电流来计算直流线损的方案更为适用于电站现场的检测。     

混合器对国六柴油机选择性催化还原系统尿素结晶的影响

针对国六柴油机选择性催化还原(selective catalytic reduction,SCR)后处理系统尿素结晶问题,设计了两种不同的混合器结构。利用计算流体动力学(computational fluid dynamics,CFD)技术对两种混合器方案的尿素碰壁位置、尿素轨迹、气流速度、流速均匀性、NH_3均匀性、压力损失等进行了仿真分析和对比,最后通过发动机台架试验验证两种方案的排放性能和结晶性能。CFD分析及试验结果表明:方案二的气流速度、流速均匀性和NH_3均匀性都优于方案一,而方案一的压力损失小于方案二;方案一台架试验的结晶质量为608g,不满足主机厂要求,方案二台架试验的结晶质量为6g,满足主机厂要求。CFD分析和试验结果趋势一致,表明CFD分析是合理有效的。     

某商住楼两种不同空调方案的能耗分析

采用BIN能耗分析的方法,对天津市某一商住楼空调系统的两种不同方案进行能耗分析,比较两种系统在能源消耗上的差别,并提出了系统节能改造建议。     

扭振分析在轴功测量技术中的应用

在柴油机轴系扭振理论的基础上对通过轴应变来测功的测量信号量进行分析，并通过实例证明了这种分析在对测量信号量进行数学处理中的重要意义。     

Damping of a parallel AC-DC power system using PID power systemstabilizers and rectifier current regulators

A scheme for improving the dynamic stability of a parallel AC-DC power system is presented. It uses a proportional-integral-derivative (PID) power-system stabilizer and a PID rectifier current regulator to enhance the damping for the electromechanical mode of the system. The parameters of the proposed PID controllers are determined using a unified approach based on modal control theory. Eigenvalue analyses are performed for the system under various operating conditions in order to compare the damping effects provided by the two different control schemes. The effectiveness of the proposed damping schemes under disturbance conditions is demonstrated by computer-simulated dynamic-response tests based on a nonlinear system model     

An experimental and numerical investigation of homogeneous ignition in catalytically stabilized combustion of hydrogen/air mixtures over platinum

The gas-phase ignition of fuel-lean hydrogen/air mixtures over platinum was investigated experimentally and numerically in laminar channel-flow configurations. Experiments were performed at atmospheric pressure in an optically accessible catalytic channel combustor established by two Pt-coated parallel plates, 300 mm long (streamwise direction) and placed 7 mm apart (transverse direction). Planar laser induced fluorescence (PLIF) of the OH radical along the streamwise plane of symmetry was used to monitor the onset of homogeneous ignition, one-dimensional Raman measurements (across the 7-mm transverse direction) provided the boundary layer profiles of the major species and temperature, and thermocouples embedded beneath the catalyst yielded the surface temperature distribution. Computations were carried out using a two-dimensional elliptic fluid mechanical model that included multicomponent transport and elementary homogeneous (gas-phase) and heterogeneous (catalytic) chemical reaction schemes. Four homogeneous and three heterogeneous reaction schemes were tested in the model against measured homogeneous ignition characteristics. The differences between measured and predicted homogeneous ignition distances could be substantial (ranging from 8% to 66%, depending on the particular hetero/homogeneous schemes) and were ascribed primarily to the homogeneous reaction pathway. Sensitivity analysis indicated that the discrepancies induced by the gas-phase schemes originated either from the presence of heterogeneously-produced water due to its effectiveness as collision partner in the chain terminating reaction H + O₂ + M = HO₂ + M, or from an overall overprediction of the radical pool in the preignition zone. The heterogeneous schemes had significant differences in their surface coverage and radical fluxes, but these variations had practically no impact on homogeneous ignition. Sensitivity and reaction flux analyses have shown that this was attributed to the ability of all heterogeneous schemes to capture the measured mass-transport-limited fuel conversion and to the relative insensitivity of homogeneous ignition on the magnitude of the heterogeneous radical fluxes, provided that all radical adsorption reactions (OH, H, and O) were included in the heterogeneous schemes.     

链条炉燃烧控制系统方案分析

本文分析了现行的几种逻条炉燃烧控制方案。提出卫种简单易行的新方案，仿真试验表明，该方案控制效果良好。     

溪落渡电站地下厂房防渗排水系统研究

对座落在特殊岩石层中和高水位区的溪落度电站地下厂房洞室群防渗排水布置，进行了多方案计算比较，并从不同方面做了较深入的分析，提出了“分层设防，表降深排”等建议。     

海上升压站主变压器冷却方式选择

由于盐雾腐蚀的原因,通常将海上升压站电气设备布置在封闭的空间内。但由此带来设备的散热面临巨大挑战,尤其是散热量最大的主变压器。为此,对变压器自冷方式在海上升压站所面临的挑战进行分析,提出了一种变压器闭式循环水冷系统的设计方案。通过对两种方式进行的技术经济比较,得出了水冷方式比自冷方式更适合海上升压站的结论。     

Linking renewable energy CDM projects and TGC schemes: An analysis of different options

Renewable energy CDM (RE-CDM) projects encourage cost-effective GHG mitigation and enhanced sustainable development opportunities for the host countries. CERs from CDM projects include the value of the former benefits (i.e., “climate change benefits”), whereas the second can be given value through the issuing and trading of tradable green certificates (TGCs). Countries could agree to trade these TGCs, leading to additional revenues for the investors in renewable energy projects and, therefore, further encouraging the deployment of CDM projects, currently facing significant barriers. However, the design of a combination of CDM projects and TGC schemes raises several conflicting issues and leads to trade-offs. This paper analyses these issues, identifies the alternatives that may exist to link TGC schemes with RE-CDM projects and analyses the impacts of those options on different variables and actors.     

Simplified stable crack growth analyses of welded CT specimens—comparison study of GE/EPRI, reference stress and R6 methods

This paper describes some simplified stable crack growth analyses of two kinds of inhomogeneous CT specimens. The one is machined from a submerged are welded plate of a nuclear pressure vessel A533B Class 1 steel, while the other is machined from an electron-beam welded plate of the A533B Class 1 steel and a high strength HT80 steel. In both specimens, initial cracks are placed to be normal to the fusion line. The ratio of yield stresses of the weld metal and the base metal of the A533B Class 1 steel is about 1·15, while that of the HT80 and the A533B Class 1 steels is about 1·4.

The generation phase crack growth analyses using the GE/EPRI and the reference stress methods are performed, calculating an applied load (P) and the J-value, while the application phase analyses of analyses using the R6 method are performed to calculate the maximum value of the applied load (P_max). Finally, some modification procedures of the three simplified estimation schemes are discussed in order to apply them to inhomogeneous material regimes.     

Conservation Properties of Unstructured Finite-Volume Mesh Schemes for the Navier-Stokes Equations

The Navier-Stokes equations describe fluid flow by conserving mass and momentum. There are two main mesh discretizations for the computation of these equations, the collocated and staggered schemes. Collocated schemes locate the velocity field at the same grid points as the pressure one, while staggered discretizations locate variables at different points within the mesh. One of the most important characteristic of the discretization schemes, aside from accuracy, is their capacity to discretely conserve kinetic energy, specially when solving turbulent flow. Hence, this work analyzes the accuracy and conservation properties of two particular collocated and staggered schemes by solving various problems.     

High-pressure catalytic combustion of methane over platinum: In situ experiments and detailed numerical predictions

The catalytic combustion of fuel-lean methane/air premixtures over platinum was investigated experimentally and numerically in the pressure range 4 to 16 bar. Experiments were performed in an optically accessible, laminar channel-flow catalytic reactor. In situ, spatially resolved Raman measurements of major species and temperature over the reactor boundary layer were used to assess the heterogeneous (catalytic) reactivity and planar laser-induced fluorescence (LIF) of the OH radical confirmed the absence of homogeneous (gas-phase) ignition. Numerical predictions were carried out with a two-dimensional elliptic code that included elementary heterogeneous and homogeneous chemical reaction schemes. Comparisons between measurements and numerical predictions have led to the assessment of the high-pressure validity of two different elementary heterogeneous chemical reaction schemes for the complete oxidation of methane over platinum. It was shown that the catalytic reactivity increased with increasing pressure and that crucial in the performance of the heterogeneous reaction schemes was the capture of the decrease in surface free-site availability with increasing pressure. Even in the absence of homogeneous ignition, the contribution of the gaseous reaction pathway to the conversion of methane could not be ignored at high pressures. The delineation of the regimes of significance for both heterogeneous and homogeneous pathways has exemplified the importance of the preignition gaseous chemistry in many practical high-pressure catalytic combustion systems. Sensitivity and reaction flux analyses were carried out on a validated elementary heterogeneous reaction scheme and led to the construction of reduced catalytic reaction schemes capable of reproducing accurately the catalytic methane conversion in the channel-flow configuration as well as in a surface perfectly stirred reactor (SPSR) and, when coupled to a homogeneous reaction scheme, the combined heterogeneous and homogeneous methane conversions. A global catalytic step could not reproduce the measured catalytic reactivity over the entire pressure range 4 to 16 bar.