An optimal design for axial-flow fan blade: theoretical and experimental studies

The technique of inverse design problem (IDP) for optimizing the three-dimensional shape of an axial-flow fan blade based on the desired airflow rate is presented in this work. The desired volume flow rate of air can be obtained from the airflow rate of the existing axialflow fan by multiplying it with a constant which is greater than unity. The geometry of the redesigned fan blade is generated using numerous design variables, which enables the shape of the fan blade to be constructed completely; thus the technique of parameter estimation for the inverse design problem can be used in this study. Results show that with the redesigned optimal fan blade, the airflow rate of fan can be increased, thereby improving the performance of the axial-flow fan. Finally, to verify the validity of this work, the prototypes of the original and optimal axial-flow fan blades are fabricated and fan performance tests are conducted with these blades on the basis of the AMCA-210-99 standard. The algorithm used in the present study can be applied to the blade design problem in any propulsion and power systems.     

离心压缩机叶轮的形状优化设计

提出一种新的优化方法离心叶轮的形状优化问题，即在遗传算法中加入自适应算子调节个体变异概率，来保证搜索的全局性和种群的多样性。并在寻优过程中加入生物生长来加快其寻优速度。最后，采用遗传算法和改进的遗传算法－生物生长法两种方法，对叶轮进行优化设计。计算结果表明改进的遗传算法－生物生长法，在较少的优化时间得到最优解。     

混沌遗传优化算法及其在机械优化设计中的应用

为了解决传统遗传算法的早熟问题，首次提出了混沌移民算子。利用混沌迭代的遍历性和内在随机性。通过混沌移民操作可克服传统遗传算法中的近亲繁殖问题，确保算法的全局收敛性。用MⅣ啪语言研制了混沌遗传优化算法软件；数值计算表明，该算法的全局收敛性好、算法稳健，适应于求解连续变量的无约束及有约束优化机械优化设计问题，具有工程实用价值。     

航空发动机离心通风器分离能力评价方法及其转子优化设计

运用离心力平衡原理建立可分离油珠直径的计算公式,提出离心通风器分离油雾的能力评价方法.通过对离心通风器核心部件转子的结构多目标优化设计,得出转子结构不同参数对离心通风器分离能力的影响,为优化离心通风器设计提供一种较好的方法.     

An algorithm for the determination of optimal design parameters of x̄control charts

One of the main difficulties in the use of an economic design of reliable optimum values for the design parameters compared with a control chart is the computation of the design parameters n (sample size), h (sampling interval) and k (control limit factor). A very simple procedure is described in this research to determine the design parameters of an x̄ control chart in Duncan’s economic model, such that they minimise the expected total costs per time unit. Numerical examples give more accurate and more published results.     

Multi-objective optimization design and experimental investigation of centrifugal fan performance

Current studies of fan performance optimization mainly focus on two aspects： one is to improve the blade profile, and another is only to consider the influence of single impeller structural parameter on fan performance. However, there are few studies on the comprehensive effect of the key parameters such as blade number, exit stagger angle of blade and the impeller outlet width on the fan performance. The G4-73 backward centrifugal fan widely used in power plants is selected as the research object. Based on orthogonal design and BP neural network, a model for predicting the centrifugal fan performance parameters is established, and the maximum relative errors of the total pressure and efficiency are 0.974% and 0.333%, respectively. Multi-objective optimization of total pressure and efficiency of the fan is conducted with genetic algorithm, and the optimum combination of impeller structural parameters is proposed. The optimized parameters of blade number, exit stagger angle of blade and the impeller outlet width are seperately 14, 43.9~, and 21 cm. The experiments on centrifugal fan performance and noise are conducted before and after the installation of the new impeller The experimental results show that with the new impeller, the total pressure of fan increases significantly in total range of the flow rate, and the fan efficiency is improved when the relative flow is above 75%, also the high efficiency area is broadened. Additionally, in 65% -100% relative flow, the fan noise is reduced. Under the design operating condition, total pressure and efficiency of the fan are improved by 6.91% and 0.5%, respectively. This research sheds light on the considering of comprehensive effect of impeller structrual parameters on fan performance, and a new impeller can be designed to satisfy the engineering demand such as energy-saving, noise reduction or solving air pressure insufficiency for power plants.     

An experimental apparatus for plasmochemical studies

An experimental plasmochemical apparatus is described to study physical and chemical processes in gas flows with a wide range of physical states and parameters; knowledge about this is necessary when developing promising vacuum technologies. The equipment allows investigation of supersonic improperlyexpanded jets, interaction of jets with barriers, kinetics of discharge-initiated plasmochemical reactions, an ionic or electron beam in condensing flows of gases and gas mixtures, relaxation, cluster formation and condensation processes, as well as modeling a nozzle flow in a wide range of gas-dynamics parameters. The apparatus is equipped with modern measuring instrumentation and a set of optical, electronic, ionic, chromatographic, and mass-spectrometric systems.     

Cat Swarm Optimization algorithm for optimal linear phase FIR filter design

In this paper a new meta-heuristic search method, called Cat Swarm Optimization (CSO) algorithm is applied to determine the best optimal impulse response coefficients of FIR low pass, high pass, band pass and band stop filters, trying to meet the respective ideal frequency response characteristics. CSO is generated by observing the behaviour of cats and composed of two sub-models. In CSO, one can decide how many cats are used in the iteration. Every cat has its′ own position composed of M dimensions, velocities for each dimension, a fitness value which represents the accommodation of the cat to the fitness function, and a flag to identify whether the cat is in seeking mode or tracing mode. The final solution would be the best position of one of the cats. CSO keeps the best solution until it reaches the end of the iteration. The results of the proposed CSO based approach have been compared to those of other well-known optimization methods such as Real Coded Genetic Algorithm (RGA), standard Particle Swarm Optimization (PSO) and Differential Evolution (DE). The CSO based results confirm the superiority of the proposed CSO for solving FIR filter design problems. The performances of the CSO based designed FIR filters have proven to be superior as compared to those obtained by RGA, conventional PSO and DE. The simulation results also demonstrate that the CSO is the best optimizer among other relevant techniques, not only in the convergence speed but also in the optimal performances of the designed filters.     

Tribological design considerations in fans and blowers

The paper describes three cases of excessive wear of the blades of different blowers and fans used in the steel industry in India. Wear was due to the inadequate aerodynamic design of either the blower or of the suction and delivery passages, causing turbulence and eddies. In two cases suitable aerodynamic modifications resulted in improved blade life. In the third case where space limitations did not permit modifications, hard facing of the blades gave satisfactory results.     

静电粉体流量计的理论与实验研究

应用于燃煤电站气力输送系统的圆环式静电流量计可为监控煤粉的流动提供极有价值的参考信息.本文利用有限元方法研究了流量计的静电感应机理,并建立了传感器检测信号与运动荷电粉体关系的数学模型.理论分析表明,静电流量计信号的输出不仅取决于探头的几何形状、检测电路参数、颗粒荷电量的大小和空间分布,还与颗粒的速度、自身携带电荷随时间的变化率等因素有关.利用传送带实验装置对上述理论分析进行了初步的验证,并在Teesside大学气力输送系统上对内径为40 mm的静电流量计,在不同的气固比条件下,获取了粉体质量流量和检测信号的标定结果.     

An ant-based clustering algorithm for manufacturing cell design

This paper proposes a new part clustering algorithm that uses the concept of ant-based clustering in order to resolve machine cell formation problems. The three-phase algorithm mainly utilizes distributed agents which mimic the way real ants collect similar objects to form meaningful piles. In the first phase, an ant-based clustering model is adopted to form the initial part families. For the purpose of part clustering, a part similarity coefficient is modified and used in the similarity density function of the model. In the second phase, the K-means method is employed in order to achieve a better grouping result. In the third phase, artificial ants are used again to merge the small, refined part families into larger part families in a hierarchical manner. This would increase the flexibility of determining the number of final part families for the factory layout designer. The proposed algorithm has been developed into a software system called the ant-based part clustering system (APCS). In addition to part family formation, APCS performs the tasks of machine assignment and performance evaluation. Finally, performance evaluation of the proposed algorithm was conducted by testing some well-known problems from literature. The evaluation results show that the algorithm is able to solve the cell formation problems effectively.     

模拟退火算法在抓斗优化设计中的应用

简介模拟退火算法,提出一个适合于求解连续变量约束非线性规划问题的算法,给出了相应的框图。使用此算法求解了抓斗机构的优化设计以提高抓斗的抓取能力,并将计算结果与传统优化算法的计算结果进行了对照。     

基于神经网络及遗传算法的齿轮化设计软件

将人工智能中BP神经网络与遗传优化算法相结合,有效解决局部极小和收敛速度以及含有连续/离散混合变量的优化问题,通过VB语言与Matlab软件混合编程,开发了齿轮优化设计软件,实现齿轮传动的自动优化设计,极大地提高了齿轮的设计效率和质量.     

生成矩形毛坯最优三块排样方式的精确算法

采用三块排样方式,基于背包问题和动态规划算法,用两条成T形的剪切线将板材分成三个矩形区域,每个区域中包含一个由同尺寸毛坯组成的规范块.实验计算表明,所述算法时间效率合理,能够有效提高材料利用率和简化切割下料过程.     

基于遗传算法和多智能体的染缸生产排产与动态优化设计

为解决小批量、多品种浸染生产不合理调度导致高能耗和多污染排放的问题,提出了一种基于遗传算法和多智能体染缸调度与动态优化的方法.该方法基于染缸车间制造执行系统、企业资源计划和过程控制系统实时数据,采用分层调度算法.其中静态层采用支持多产品的批处理、多染缸的非等同性、前期订单、订单交货期和切换成本等约束条件的遗传算法;动态层采用支持染缸运行状态的多智能体的协调动态优化算法.通过对生产过程中多约束条件和多动态变化因素的算法求解,获得染缸作业任务动态优化设计.仿真结果表明,与单纯遗传算法和人工调度相比,基于数据驱动的分层动态优化调度达到了染缸作业排产优化和污染减排的目标和实际应用的可行性.     

Numerical and experimental investigation of the bell-mouth inlet design of a centrifugal fan for higher internal flow rate

The energy efficiency of a household refrigerator is one of the most critical characteristics considered by manufacturers and consumers. Numerous studies in various fields have been conducted to increase energy efficiency. One of the most efficient methods to reduce the energy consumption of a refrigerator is by improving the performance of fans inside the refrigerator. A number of studies reported various ways to enhance fan performance. However, the majority of these studies focused solely on the fan and did not consider the working environment of the fan, such as the inlet and outlet flow characteristics. The expected performance of fans developed without consideration of these characteristics cannot be determined because complex inlet and outlet flow passage could adversely affect performance. This study investigates the effects of the design of the bell-mouth inlet on the performance of a centrifugal fan in a household refrigerator. In preliminary numerical studies, significant flow loss is identified through the bell-mouth inlet in the target fan system. Several design factors such as tip clearance, inner fence, motor-box struts, and guide vane are proposed to resolve these flow losses. The effects of these factors on fan performance are investigated using computational fluid dynamics techniques to solve incompressible Reynolds-averaged Navier-Stokes equations for predicting the circulating flow of the fan. Experiments are then performed to validate the numerical predictions. Results indicate that four design factors positively affect fan performance in terms of flow rate. The guide vane is the most effective design factor to consider for improving fan performance. Further studies are conducted to investigate the detailed effects of the guide vane by varying its install angle, install location, height, and length. These studies determine the optimum design of the guide vane to achieve the highest performance of the fan and the related flow characteristics around the bell mouth.     

An elitist strategy genetic algorithm for integrated layout design

While designing the layout of any manufacturing organizations, the primary objective is to decide an optimal arrangement of their departments (machines or cells) in a two-dimensional shop floor (facility) satisfying desired objectives, which is termed facility layout problem (FLP). In traditional layout design philosophy, the inter-cell layout and flow path layout design of material handling system (MHS) was carried out step by step in a sequential manner. This results in sub-optimal solutions for FLP. In this paper, an integrated approach is adopted to design the inter-cell layout and the flow path layout of MHS simultaneously. The quality of the final layout is evaluated by minimizing the weighted sum of two distance-based cost objectives namely, (1) total material handling cost. (2) Distance-weighted cost of total closeness rating score. Sequence-pair (SP) representation is used for layout encoding. The translation from SP to layout is efficiently done by longest common subsequence methodology. Due to NP-hard nature of the proposed problem, an elitist strategy genetic algorithm (ESGA) is developed and tested with three test problem instances available in the literature. It is found that the proposed ESGA algorithm is able to produce the best solutions consistently, twice faster than the standard GA for the test problem instances.     

液体火箭发动机超低比转速离心泵优化设计

选择液体火箭发动机用高速超低比转速离心泵作为研究对象,运用FLUENT流体计算软件及GAMBIT前处理软件,采用三维K-ε双模型方程对其内部流场进行计算,从优化泵内流动特性的角度出发,优化设计了一台高扬程、高效率、能在大流量范围稳定工作的超低比转数离心泵.试验表明,这种结合内流场特性的优化设计是可行的,而且是快速高效的.     

Series design of compressors for two-stage centrifugal chiller

A preliminary series design of compressors for a two-stage centrifugal chiller is suggested. Six groups of hydrodynamically similar compressors, ranging from 233RT to 1,200RT, are introduced. Flow rates, impeller diameters, and wheel speeds for each group are determined from hydrodynamic similarity to share impellers of adjacent groups. It is expected that these compressors can have the same performance and efficiency from the smallest model to the largest one.     

改进型遗传算法在机械优化设计中的应用研究

针对标准遗传算法局部搜索能力弱的特点,将其与随机方向法结合,提高其局部搜索能力。结合工程问题进行优化计算,结果表明,此算法优于标准遗传算法。