离心压缩机三元叶轮形状优化设计

在三维参数化建模的基础上,对某离心三元叶轮进口叶片的前缘进行了形状优化设计,在叶轮质量和变形满足要求的条件下,得到了叶轮进口叶片前缘的最优结构尺寸参数.降低了叶轮最大应力并改善了应力分布状态,为离心压缩机三元叶轮设计提供了重要的依据.     

某型离心压缩机叶轮优化设计

针对某型离心压缩机实施改进结构和气动设计,并对其进行数值模拟。采用有限元方法对叶轮进行静力学计算和长寿命疲劳计算,计算出叶轮各部分的应变值和疲劳寿命,分析了叶轮可能出现的问题,并在此基础上对叶轮进行结构和气动优化设计。计算结果表明:改型离心叶轮达到了性能指标要求,可为类似的离心压缩机改型气动设计提供借鉴。     

混合遗传算法进行离心叶轮优化设计

利用自适应交叉遗传算法和生物生长算法的特点，提出一种新的优化方法——混合生物生长自适应交叉遗传算法。该方法既充分利用了遗传算法全局寻优和生物生长法快速收敛的优点，又弥补了遗传算法收敛速度过慢和生物生长法过分依赖结构初始形状的不足。为了验证优化方法的正确性和合理性，对某三维离心叶轮进行优化设计，结果表明，混合算法较单纯采用遗传算法收敛速度快，且可得到形状优化最优解。     

离心压缩机叶片前缘形状对强度计算的影响

以某大型离心式压缩机的闭式叶轮为研究对象,在研究叶片前缘形状对叶轮性能的影响过程中,利用CAD软件Solidworks对3个闭式叶轮进行三维实体造型,并运用有限元软件ANSYS进行数值模拟计算.主要对比研究了钝形、圆形和椭圆形前缘对叶轮强度的影响.数值计算的结果表明:叶片前缘几何形状对离心压缩机的结构强度具有影响.     

离心叶轮超速工具优化设计及改进

主要从离心叶轮超速过程入手,深入分析影响叶轮超速的主要因素,提出了解决措施和改进方案,减少了重复超速次数,提高了叶轮超速试验效率。     

基于神经网络与遗传算法的离心叶轮结构优化设计

采用前馈神经网络实现离心叶轮的三维结构设计,考虑到BP算法存在收敛速度慢和可能收敛到局部极小点的弱点,利用改进的遗传算法参与神经网络的结构演化和网络训练,以获得最佳网络拓扑结构,并使得网络的训练以较大的概率获得全局最优.所建立的神经网络用于求解给定应力分布情况下的离心叶轮形状.计算表明该神经网络可以精确的预测叶轮边界形状.     

离心压缩机叶轮结构优化设计

叶轮是离心压缩机的核心部件之一,对于悬臂结构的转子系统,叶轮的质量和应力大小直接影响着转子的安全稳定性,因此对叶轮进行结构优化设计,降低质量和应力尤为关键。本文综合有限元分析方法和数学优化算法,对某型号蒸汽压缩机半开式叶轮进行优化设计,优化后叶轮质量降低27.1kg,降低约16.1%,叶轮最大等效应力降低196.4MPa,降低约18.5%,优化设计效果明显,对降低成本和提高机组转子稳定性有着重要意义,具有良好的工程实用价值。     

多级离心压缩机叶轮外径切割的估算方法

将文献１提出的单级离心压缩机叶轮外径切割的估算方法推广应用于多级离心压缩机，扩大了该方法在实际中的使用范围。     

改进的生物生长法及其在离心叶轮三维形状优化设计中的应用

考虑到传统生物生长法只能对简单形状进行优化的局限性,结合复杂结构的三维形状优化设计,对生物生长法提出三点改进:①不直接采用修正后节点坐标来调整网格,利用B样条函数描述修改后结构的外边界。②构造出在满足应力和几何条件下可使结构重量最轻的目标函数,进而大大增强了生物生长法在处理复杂结构形状优化设计方面的能力。③在生物生长法形状优化过程中,采用罚方法对违反约束条件的个体给予惩罚。作为工程实例,该方法被用于某三维离心叶轮的结构形状优化设计。计算结果表明,该方法可在较短时间内得到满足各种应力和几何约束的重量最轻解。     

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.     

基于SolidWorks的化工离心泵叶轮模具设计

针对传统离心泵叶轮设计步骤繁琐的不足,提出了基于SolidWorks的三维参数化离心泵叶轮注塑模设计方法。简单介绍了SolidWorks的主要功能模块及离心泵叶轮模具设计的流程,详细阐述了离心泵叶轮模具设计的步骤。设计中,叶轮采用尼龙6/10材料,其拔模斜度为1.5°,收缩率为1%。通过对模具各零部件的造型与实时修改,实现了离心泵叶轮模具的参数化设计,并完成了模具的虚拟装配及加工出详图的快速输出。本方法对工程设计具有一定的实用价值。     

A five-axis rough machining approach for a centrifugal impeller

A clear trend shows that most products or mechanical components, especially those regarding aerospace applications, are designed to fit the requirements of free form surface features. When a 3-axis computer numerical controlled (CNC) machining centre is used to produce a typical centrifugal impeller, great difficulties, i.e., collisions between the cutting tool and impeller, need to be overcome. In this case, sophisticated five-axis machines have to be utilised. Presently, most commercial computer-aided manufacturing (CAM) systems for five-axis control are lacking generality, and functions for the rough tool-path generation are far less than required. The rough machining is recognised as the most important procedure influencing the machining efficiency and is critical for the success of the following finishing process. However, great difficulties are expected to arise in performing five-axis rough machining. The main objective of the present study is to overcome this problem by combining related machining technology. As a result, CL data based on the geometry model of blade and hub of the impeller are generated. Finally, the CL data is confirmed through software simulation. The results of verification prove the machining methodology and procedure to be successful.     

高速离心叶轮内部三维粘性流场的数值模拟

采用一种快速求解三维黏性流场的计算方法求解某离心压气机内部复杂的流场，该方法利用Denton J．D．教授的粘性体积力法模拟粘性对叶轮机械内部流动的影响，采用时间推进法和有限体积差分格式对叶轮机械内部的流动进行求解。为加速收敛，使用了多重网格法，当地时间步长和局部残差光顺技术。对某离心压气机内部流动进行了详细的数值模拟，得出了压气机转子性能、叶顶周向平均静压以及准正交面上子午速度分布图，计算结果与试验结果吻合良好。采用该方法详细分析了不同工况下离心压气机内部流场。     

水下航行器壳体外形优化设计

同时把阻力和噪声作为目标函数,建立了低阻低噪回转体形水下航行器外形的多目标优化设计数学模型。水洞试验数据和计算结果表明,优化外形阻力有较大降低,自噪声性能有一定改善。     

离心式固液两相流泵的叶轮设计

阐述离心式固液两相流泵的叶轮设计的方法,分析了基于不同两相流理论的叶轮参数的选择方法,指出叶轮型线设计是固液两相流泵设计的重要环节,并阐述了基于边界层理论的叶片型线设计方法。     

低比转速离心泵叶轮的设计

通过对叶轮内液流流动分析 ,提出了减小叶轮出口射流——尾流结构的措施。为减小圆盘摩擦损失 ,对叶轮结构采取了适量车削前后盖板、周向修圆叶片的方法。     

Effect of piping systems on surge in centrifugal compressors

There is a possibility that the exchange of the piping system may change the surge characteristic of a compressor. The piping system of a plant is not always the same as that of a test site. Then it is important to evaluate the effect of piping systems on surge characteristics in centrifugal compressors. Several turbochargers combined with different piping systems were tested. The lumped parameter model which was simplified to be solved easily was applied for the prediction of surge point. Surge lines were calculated with the linearlized lumped parameter model. The difference between the test and calculated results was within 10%. Trajectory of surge cycle was also examined by solving the lumped parameter model. Mild surge and deep surge were successfully predicted. This study confirmed that the lumped parameter model was a very useful tool to predict the effect of piping systems on surge characteristics in centrifugal compressors, even though that was a simple model. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

Impeller inlet geometry effect on performance improvement for centrifugal pumps

This research treats the effect of impeller inlet geometry on performance improvement for a boiler feed pump, who is a centrifugal pump having specific speed of 183 m·m³min⁻¹·min⁻¹ and close type impeller with exit diameter of 450 mm. The hydraulic performance and cavitation performance of the pump have been tested experimentally. In order to improve the pump, five impellers have been considered by extending the blade leading edge or applying much larger blade angle at impeller inlet compared with the original impeller. The 3-D turbulent flow inside those pumps has been analyzed basing on RNG k-ɛ turbulence model and VOF cavitation model. It is noted that the numerical results are fairly good compared with the experiments. Based on the experimental test and numerical simulation, the following conclusions can be drawn: (1) Impeller inlet geometry has important influence on performance improvement in the case of centrifugal pump. Favorite effects on performance improvement have been achieved by both extending the blade leading edge and applying much larger blade angle at impeller inlet; (2) It is suspected that the extended leading edge have favorite effect for improving hydraulic performance, and the much larger blade angle at impeller inlet have favorite effect for improving cavitation performance for the test pump; (3) Uniform flow upstream of impeller inlet is helpful for improving cavitation performance of the pump. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.