2D numerical study on the deflection of thin steel plate subjected to gaseous detonation wave interaction

An elaborate numerical study with a validated LS-DYNA® immersed boundary method fluid-solid interaction code is used to characterize the influence of pre-detonation pressure, ignition point location and time duration on plastic deformation of thin steel plates subjected to hydrogen-oxygen gaseous detonation. Simulation relies on the modeling of detonation by chemical reaction kinetic and its propagation by conservative element solution element solver. Immersed boundary method is used to simulate the interface motion between the detonating gas and the deforming plate to facilitate the assessment of fluid pressure distribution on the plate surface. The numerical tool relates the pressure distribution and gaseous detonation parameters to the plate macroscopic deformation by employing multi-species reactive Euler's equations for the gas and assuming a Johnson-Cook material model for the plate. The numerical model simulated the experimental tests and a good agreement between them was obtained where specific features of gas detonation-driven forming were considered. With the confidence of the validation, the numerical model investigated the effects of different parameters such as the gaseous mixture initial temperature and combustion cylinder longitudinal capacity on overpressure-time history and strain-time history. It is demonstrated that the larger longitudinal capacity of combustion cylinder and more distant ignition point location have a great influence on increasing the detonation wave intensity. Eventually, the rate-dependent Johnson-Cook failure criterion was used to assess the failure state of plate under high-intensity detonations.     

Optimal design of high pressure hydrogen storage vessel using an adaptive genetic algorithm

The weight minimum optimization of composite hydrogen storage vessel under the burst pressure constraint is considered. An adaptive genetic algorithm is proposed to perform the optimal design of composite vessels. The proposed optimization algorithm considers the adaptive probabilities of crossover and mutation which change with the fitness values of individuals and proposes a penalty function to deal with the burst pressure constraint. The winding thickness and angles of composite layers are chosen as the design variables. Effects of the population size and the number of generations on the optimal results are explored. The results using the adaptive genetic algorithm are also compared with those using the simple genetic algorithm and the Monte Carlo optimization method.     

影响遗传算法PID参数优化性能的主要因素

针对影响遗传算法性能的主要因素进行讨论,并结合PID励磁调节器参数优化,对不同编码方式、遗传算子的控制器参数优化情况进行比较分析。所得结果对应用遗传算法在线调整控制参数具有指导意义。     

A Real—coded Genetic Algorithm Applied to Optimum Design of a Low Solidity Vaned Diffuser for Diffuser Pump

A numerical procedure for hydrodynamic redesign of the conventional vaned diffuser into the low solidity vaned diffuser by means of a real-coded genetic algorithm with Boltzmann,Tournament and Roulette Wheel selection is presented.In the first part,an investigation on the relative efficiency of the different real-coded genetic algorithm is carried out on a typical mathematical test function.The real-coded genetic algorithm with Boltzmann selection shows the best optimization performance compared to the Tournament and Roulette Wheel selection.In the second part,an approach to redesign the vaned diffuser profile is introduced.Goal of the optimum design is to search the highest static pressure recovery coefficient and low solidity vaned diffuser.The result of the low solidity vaned diffuser optimum design confirms that the efficiency and optimization performance of the real-coded Boltzmann selection genetic algorithm outperforms the other selection methods.A comparison between the designed low solidity vaned diffuser and original vaned diffuser shows that the diffuser pump with the redesigned low solidity vaned diffuser has the higher static pressure recovery and improved total hydrodynamic performance.In addition,the smaller outlet diameter of designed vaned diffuser tends to a more compact size of diffuser pump compared to the original diffuser pump.The obtained results also demonstrate the real-coded Boltzmann selection genetic algorithm is a promising optimization algorithm for centrifugal pumps design．     

基于遗传算法的机车车辆横向动力学多参数优化设计

将遗传算法应用于机车车辆横向动力学,设计了适用于动力学多参数的优化方案,编制了遗传算法程序。然后,通过建立机车横向动力学模型并进行6参数优化,得到了各参数在可行域内的最优解。     

Electromagnetic design and dynamic analysis of large turbo-generator

Through a great deal calculation, the design and simulation analysis of stator parametric and rotor electromagnetic system of 1000MW turbo-generator are performed by using Ansoft Maxwell Rmxprt12.1 software. Besides. the basic parameters of the generator, the geometry dimensions of the stator and rotor, type and sizes of the slots, coils and windings parameters and the way of windings connection are determined. The finite element model of electromagnetic systems of generator stator and rotor was constructed by Ansoft Maxwe112D3D 12.1, and the transient electromagnetic characteristics of generator was analyzed and simulated. The 3D geometric models of turbo-generator were established respectively by using PROE software, and the dynamic finite element model of generator structure was built by ANSYS workbench 11.0. In addition, the dynamic characteristics of stator iron core, stator frame were calculated respectively. The simulation calculation has shown that the structural parameters, material parameters, and the electromagnetic characteristics parameters for large turbogenerator that are put forward by this paper should be optimal. and the design plan and method suggested by this paper should be feasible. The paper provides an effective solution for the development of larger turbo-generator than 1000 MW.     

Optimal design of a modular axial-flux permanent-magnet synchronous generator for gearless wind turbine applications

Air-cored axial-flux permanent-magnet synchronous generators (AFPMSGs) are potential candidates for gearless direct-coupled wind turbines (DCWTs) owing to providing high efficiency and power density. The design of a DCWT generator is so complicated since the generator cost, dimension, and weight affected by gear elimination. Therefore, it is essential to find an optimal AFPMSG design at rated conditions. In this paper, an accurate procedure for the optimal design of an air-cored AFPMSG applicable for DCWTs is proposed. The genetic algorithm (GA) is used for multi-objective design optimization to reach the optimal configuration as well as system dimension in order to decrease the weight, increase the power density and enhance the effectiveness of the generator. To validate the efficiency of the suggested optimization proceducer, a 30 kW AFPMSG has been considered as a case study. The results of optimization have been investigated by finite element analysis (FEA). A prototype generator is also fabricated, and the test results are offered and compared with the numerical study. The outcomes show that there exists an acceptable agreement between FEA and experimental outcomes with the error percentage about of 1.35%.     

Novel heat transfer issues associated with the design and safe operation of the MEGAPIE spallation source target

Critical heat transfer problems are discussed in the context of the operation of a spallation source target, which represents a first demonstration of the feasibility of an innovative concept for generating energy using a particle accelerator. Within the framework of the umbrella project MEGAPIE, an R&D support group was organized to take responsibility for target cooling. This involved the use of advanced numerical methods — Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) — validated against suitable experimental data, and by means of appropriate benchmarking exercises. The design studies using CFD resulted in an optimum flow configuration being defined for the coolant circulation. Flow visualization tests were undertaken using a glass/water test section, with the velocity field mapped using optical and ultrasonic measuring techniques. These were followed by heat transfer tests, using the actual target materials (lead-bismuth-eutectic coolant and steel confinement). Further CFD/FEM work to analyze operational transients and accident sequences was also carried out, and is described in the paper.     

Application of genetic algorithm to the optimal‐chilled water supply temperature calculation of air‐conditioning systems for saving energy

The values of chilled water supply temperatures of chillers indicate their load distributions due to the chilled water return temperatures of all chillers being the same in a decoupled air‐conditioning system. This study employs genetic algorithm (GA) to find out the chilled water supply temperatures of chillers for solving optimal chiller loading (OCL) problem. GA overcomes the flaw that Lagrangian method is not adaptable for solving OCL as the power consumption models or the kW‐PLR (partial load ratio) curves include non‐convex functions. This study uses the chilled water supply temperature as the variable to binary code chromosomes, and execute reproduction, crossover and mutation operation. After analysis and comparison of the case study, it has been concluded that this method not only solves the problem of Lagrangian method, but also produces results with high accuracy within a rapid timeframe. It can be perfectly applied to the operation of air‐conditioning systems. Copyright © 2007 John Wiley & Sons, Ltd.     

Probability strength design of steam turbine blade and sensitivity analysis with respect to random parameters based on response surface method

Many stochastic parameters have an effect on the reliability of a steam turbine blade during practical operation. To improve the reliability of blade design, it is necessary to take these stochastic parameters into account. An equal cross-section blade is investigated and a finite element model is built parametrically. Geometrical parameters, material parameters and load parameters of the blade are considered as input random variables while the maximum deflection and maximum equivalent stress are output random variables. Analysis file of the blade is compiled by deterministic finite element method and applied to be loop file to create sample points. A quadratic polynomial with cross terms is chosen to regress these samples by step-forward regression method and employed as a surrogate of numerical solver to drastically reduce the number of solvers call. Then, Monte Carlo method is used to obtain the statistical characteristics and cumulative distribution function of the maximum deflection and maximum equivalent stress of the blade. Probability sensitivity analysis, which combines the slope of the gradient and the width of the scatter range of the random input variables, is applied to evaluate how much the output parameters are influenced by the random input parameters. The scatter plots of structural responses with respect to the random input variables are illustrated to analyze how to change the input random variables to improve the reliability of the blade. The results show that combination of the finite element method, the response surface method and Monte Carlo method is an ideal way for the reliability analysis and probability strength design of the blade. __________ Translated from Proceedings of the CSEE, 2007, 27(20): 12–17 [译自: 中国电机工程学报]     

基于灵敏度控制的某商用车前副车架轻量化设计

根据某款处于前期开发阶段的商用车前副车架的开发要求,结合有限元法对前副车架在4种典型恶劣工况进行了刚强度分析与模态分析。采用灵敏度分析方法分析了多个设计变量的轻量化潜力,最终选择可用于轻量化的板厚度变量作为尺寸优化设计变量,并对前副车架轻量化方案中的刚强度、模态特性进行了校验分析。根据疲劳寿命估计理论,采用Ncode软件对该商用车前副车架疲劳寿命进行了估计,保证了轻量化设计方案的可行性及可靠性,为今后商用车前副车架等部件在设计开发初期的轻量化设计提供了一种实例参照。     

ANSYS在机车车体结构设计中的应用

通过介绍某机车车体详细的有限元模型,描述了对车体结构分析的基本过程。并明确了车体有限元分析的主要影响因素以及对车体结构分析的基本步骤,为利用ANSYS对机车车体结构分析提供了参考依据。     

不同折转角弯曲扩压叶栅性能数值研究及优化设计

通过数值模拟研究不同折转角弯曲扩压叶栅中弯高、弯角对其气动性能影响,利用试验设计和遗传算法实施方案选择和优化设计,给出不同折转角下弯高、弯角最佳匹配范围。结果表明,3种折转角情况下弯高、弯角的最佳匹配规律是不同的,随着扩压叶栅折转角的增大,较小的弯高和弯角匹配将更有效减少气动损失。     

Solution to shape identification problem of unsteady heat‐conduction fields

This paper presents a numerical analysis method for shape determination problems of unsteady heat‐conduction fields in which time histories of temperature distributions on prescribed subboundaries or time histories of gradient distributions of temperature in prescribed subdomains have prescribed distributions. The square error integrals between the actual distributions and the prescribed distributions on the prescribed subboundaries or in the prescribed subdomains during the specified period of time are used as objective functionals. Reshaping is accomplished by the traction method that was proposed as a solution to shape optimization problems of domains in which boundary value problems are defined. The shape gradient functions of these shape determination problems are derived theoretically using the Lagrange multiplier method and the formulation of material derivative. The time histories of temperature distributions are evaluated using the finite‐element method for a space integral and the Crank–Nicolson method for a time integral. Numerical analyses of nozzle and coolant flow passage in a wing are demonstrated to confirm the validity of this method. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(3): 212–226, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10086     

Modeling,design, and optimization of a cost‐effective and reliable hybrid renewable energy system integrated with desalination using the division algorithm

People in the Middle East are facing the problem of freshwater shortages. This problem is more intense for a remote region, which has no access to the power grid. The use of seawater desalination technology integrated with the generated energy unit by renewable energy sources could help overcome this problem. In this study, we refer a seawater reverse osmosis desalination (SWROD) plant with a capacity of 1.5 m³/h used on Larak Island, Iran. Moreover, for producing fresh water and meet the load demand of the SWROD plant, three different stand‐alone hybrid renewable energy systems (SAHRES), namely wind turbine (WT)/photovoltaic (PV)/battery bank storage (BBS), PV/BBS, and WT/BBS are modeled and investigated. The optimization problem was coded in MATLAB software. Furthermore, the optimized results were obtained by the division algorithm (DA). The DA has been developed to solve the sizing problem of three SAHRES configurations by considering the object function's constraints. These results show that this improved algorithm has been simpler, more precise, faster, and more flexible than a genetic algorithm (GA) in solving problems. Moreover, the minimum total life cycle cost (TLCC = 243 763$), with minimum loss of power supply probability (LPSP = 0%) and maximum reliability, was related to the WT/PV/BBS configuration. WT/PV/BBS is also the best configuration to use less battery as a backup unit (69 units). The batteries in this configuration have a longer life cycle (maximum average of annual battery charge level) than two other configurations (93.86%). Moreover, the optimized results have shown that utilizing the configuration of WT/PV/BBS could lead to attaining a cost‐effective and green (without environmental pollution) SAHRES, with high reliability for remote areas, with appropriate potential of wind and solar irradiance.     

Optimization of the bipolar plate rib structure in proton exchange membrane fuel cells with an analytical method

In order to make proton exchange membrane fuel cell vehicles more marketable, not only should costs be reduced, but service life should also be further increased. Important factors determining the expected service life are the deformation and the stress distribution within the carbon paper gas diffusion layer (GDL), on which the rib structure of the bipolar plates (BPP) has a significant impact. Against this background, a new analytical method is firstly developed to predict the deformation and stress distribution within the GDL, due to compression by the ribs, with high accuracy and low computing resources. Based on the analytical method, a new parabolic rib geometry is then proposed, which can significantly reduce the maximum normal and shear stresses occurring within the GDL, thus reducing the possibility of its mechanical damage. The optimized rib design provides guidance for designing and processing commercial fuel cell BPPs.