不同型线的高效二元离心叶轮优化设计

对具有无叶扩压器的离心压缩机两元叶轮的三种叶片型线进行对比研究,采用单圆弧和等减速流型法设计离心叶轮叶片型线,得到其性能曲线和内部流场,运用正交设计试验方法对离心压缩机叶轮进行了变减速流型优化设计,并对比分析了变减速流型与等减速流型的性能曲线。结果表明当叶片的进出口角确定后,叶片型线改变时,叶轮做功能力略有提升,而对整个叶道内的静压和速度分布影响较大,以致影响级性能。     

节能低噪离心风机叶轮流场计算和试验研究

本文用任定准正交面方法分析了高压头离心风机采用加载式及卸载式叶片叶轮时的速度分布比较,应用考虑叶轮旋转和曲率影响的附面层动量积分关系式,计算了叶片表面的附面层动量损失厚度及壁面摩擦系数的变化情况,提出了节能低噪离心风机的设计思想;对四种叶片型线及噪声控制方案叶轮进行了气动和噪声性能试验,获得了有益的成果。     

离心风机噪声源的试验研究

本文对离心风机中所产生的气动噪声进行了试验研究,通过对两种不同的风机设计了不向的试验件,对蜗舌形状、机壳形状、叶轮叶片型线、叶片数等的组合进行气动噪声试验,并进行了分析研究,作出了合理的解释,并进一步提出了就如何降低离心风机噪声的方法。     

风机叶轮离心浇注模改进设计

通过对叶轮结构及其模具的分析,从模具定位方式,叠片方法入手,对叶轮离心浇注模进行了改进设计,增加了定位套和定位压圈,减少原来的叶片隔板,使叶片均匀分布。保证了叶轮叶片与叶轮轴套同心,从而减少了叶轮整体的初始动平衡量,达到减小风机自振动振幅。     

风机叶片噪声模型建立及应用

运用运动声源产生声场的特点,建立风机叶片噪声模型,经验证是正确的,得出叶片中影响风机噪声的主要因素是转速、叶片数、安装角、曲率半径等。控制风机噪声重点应该放在风机设计上,采取降低圆周速度、倾斜叶片、增加曲率半径等措施,从源头上控制噪声会取得较好效果。     

不等距叶片离心风机气动噪声的数值与实验研究

为探索不等距布置叶轮叶片对工业离心风机气动噪声的影响，以T9-19No．4A前向离心风机为对象，设计两个不同叶片间距的不等距叶片叶轮。运用数值定性预测及实验测量相结合的方法分析不等距叶片离心风机的气动噪声，实验结果与数值模拟结果在定性上吻合良好。     

多翼离心风机气动噪声的降噪与实验研究

本文针对多翼离心风机气动噪声的主要噪声源提出了降噪方案。首先,对于多翼离心风机涡流噪声的降噪,主要通过优化叶轮、蜗壳的结构几何参数和在叶轮出口加装旋转扩压器等方式进行。其次,对于多翼离心风机旋转噪声的降噪,主要通过改变蜗舌形式进行。最后对优化进出口安装角的叶轮和在叶轮出口加装旋转扩压器这两种降噪措施进行了试验验证。结果表明,改进后的风机与原型相比达到了显著的降噪效果。     

多翼离心风机气动噪声的降噪

针对多翼离心风机气动噪声的主要噪声源提出降噪方案。首先,对于多翼离心风机涡流噪声的降噪,主要通过优化叶轮、蜗壳的结构几何参数和在叶轮出口加装旋转扩压器等方式进行。其次,对于多翼离心风机旋转噪声的降噪,主要通过改变蜗舌形式进行。最后对优化进出口安装角的叶轮和在叶轮出口加装旋转扩压器这两种降噪措施进行试验验证。结果表明,改进后的风机与原型相比达到显著的降噪效果。     

基于模态动力学的离心风机振动特性数值研究

采用数值方法研究离心风机在流体激励力和叶轮离心力共同作用下的结构响应。离心风机在运行过程中的振动主要由流体激励力和叶轮离心力引起,传统的分析方法很难准确地模拟和预测这种流固耦合振动。首先模拟离心风机内部三维非定常流场,然后将流场分析得出的流体激励力施加到风机叶轮上,采用模态动力学方法对离心风机进行振动响应计算。研究叶片数和前盘厚度两种结构参数对离心风机振动特性的影响。结果表明,存在最佳的叶片数和前盘厚度值,使得离心风机达到较好的减振效果;增加前盘厚度有利于提高叶轮强度,但是随着前盘厚度的增加,系统振动越来越强烈,因此在叶轮设计时应充分考虑叶轮强度以及风机整机振动性能以确定最佳叶轮结构。     

基于Flow Simulation的高风压离心式风机设计

离心式风机的风压与其径向尺寸有着紧密的联系,设计时如果要求结构尺寸紧凑又要达到比较大的风压时会很难兼顾。设计过程尝试了从改进叶轮结构形状和叶片的安装角度来解决这一问题。通过气动力计算得到了叶片安装的入口和出口角度及相关尺寸,最终采用了前向型叶轮结构。依据计算的几何参数借助Solidworks三维设计软件建立了风机的几何模型。最后利用软件的Flow Simulation模块对风机进行了风压和流速的数值模拟分析,分析结果显示选用的前向型叶片满足了设计要求。     

Optimization design of axial fan blade

A series airfoil was obtained through optimization design which aimed to promote lift–drag ratio, and the new airfoil series was used to construct a blade. The chord length and installation angle of the blade along the blade height were optimized by using orthogonal optimization. Three design options (straight blades, C-type blades and forward swept blades) are examined in this paper. Taking an axial fan as the research object, the whole 3D numerical simulation was conducted by using Ansys-CFX. Axial fans with three kinds of blades are discussed and compared under design and off-design conditions. The present results show that: under design conditions, the total pressure efficiency of the axial flow fan with the forward swept blade is the highest, and the C-type blade has slightly lower efficiency while the straight blade has the lowest efficiency. Under off-design conditions, the aerodynamic performance of the forward-swept blade and C-type blade fans are better than that of the straight-blade fans.     

基于流固耦合的导叶式离心泵强度分析

运用顺序耦合和双向流固耦合方法对导叶式离心泵进行了强度分析。通过顺序流固耦合方法,对叶轮进行了静应力强度分析,并与双向流固耦合方法得到的结果进行了比较。同时,对双向流固耦合结果中最大等效应力节点A和最大变形区域的节点B在叶轮旋转一周过程中的等效应力变化的时域图以及频域图进行了分析。结果表明,最大等效应力出现在叶轮前盖板、叶片背面和叶轮出口边的交界处（节点A）;叶片进口边中部以及与前后盖板的交界处和叶片出口与后盖板的交界处这些地方有应力集中,可能发生强度破坏。后盖板出口处且正好在流道中部位置变形最大（节点B）,可能发生刚度破坏。对于静力学分析,顺序耦合与双向耦合的结果基本一致。节点A的变形量小于节点B,但交变应力的幅值却远大于节点B。疲劳裂纹的扩展速度主要取决于交变应力幅值的大小,因此,在节点A处更易发生疲劳破坏。计算结果对导叶式离心泵叶轮结构优化设计提供了有效依据。     

Stage-wise characterization of the high shear granulation process by impeller torque changing rate

Fine cornstarch powders are wet granulated in a lab-scale high shear granulator. The torque required for maintaining the impeller passing through the bed with a constant rotating speed is monitored during the continuous binder addition granulation process. A new method is proposed to identify 6 stages during the granulation process based on the fraction of the positive impeller torque changing rate in a characteristic period of time. The morphologies and the behavior of the bed are found intrinsically different in the identified 6 stages. The influence of the impeller blade inclined angle on the impeller torque in each stage is initially reported. The impeller with planner 45° blades requires higher torques in Stages I and II due to the overall powder bed mass loading. The impeller with steeper 60° blades requires higher torques in Stages III and IV due to the higher collision frequencies between the blade and granules. The suitable granulation liquid binder to solid powder mass ratio can be readily identified in Stages II and III, and its range is found to increase with the increasing of the impeller rotational speed and is independent to the blade inclined angle.     

Einfluß der Schaufelgeometrie auf den Kennliniengradienten von Seitenkanalmaschinen

Side channel machines are mainly constructed with straight, radial arranged or forward writhed blades. The energy transfer from the impeller to the fluid medium is accomplished by the flow processes in the lateral open or semiopen impeller and in the side channel. With regard to a high and effective energy transfer the geometries of the impeller and the side channel have to be tuned one upon the other in order to reach high pressure coefficients, high gradients of the characteristic lines and high efficiencies. The geometries of the impeller and the blade are characterized by the outer and inner radii and the width of the impeller. The geometry of the blade is characterized by the ratio of the radii and the number of blades, especially the blade angle at the edge of the blade. Therefor some criteria of optimization will be given.     

Numerical simulation of solid-liquid mixing characteristics in a stirred tank with fractal impellers

The hydrodynamics of solid-liquid mixing process in a stirred tank with four pitched-blade impellers, fractal 1 impellers, and fractal 2 impellers were investigated using computational fluid dynamics (CFD) simulation. An Eulerian-Eulerian approach, standard k-ε turbulence model, and multiple reference frames (MRF) technique were employed to simulate the solid-liquid two-phase flow, turbulent flow, and impeller rotation, respectively. The effects of impeller speed, impeller type, impeller spacing, impeller blade tilt angle, impeller blade shape, solid particle size and initial solid particle loading on the solid particle suspension quality were investigated. Results showed that the homogenous degree of solid-liquid system increased with the increase of impeller speed. The impeller spacing of T5/6 and T and impeller blade tilt angle of 60° and 45° were appropriate for the solid-liquid suspension process. Fractal shape impeller was more efficient than jagged shape impeller in solid-liquid mixing process. Larger particle diameter and higher initial solid particle loading resulted in less homogenous distribution of solid particles. It was found that fractal impeller could improve the solid particle suspension quality compared with four pitched-blade impeller under the same power consumption, increasingly so with the fractal iteration number of fractal impeller. Moreover, fractal impeller reduced the size of impeller trailing vortex and consumed less power consumption compared with four pitched-blade impeller at the same impeller speed, and the more the number of fractal iteration, the higher the impeller energy utilization rate of fractal impeller.     

带尾缘吹气的空心叶轮轴流式风机内部流动和气动噪声模拟

对带尾缘吹气的空心叶轮轴流式风机内部流动和气动噪声进行数值模拟计算,并从流动性能和噪声水平2个方面将之与原型风机进行对比分析。结果表明：两者的流动性能差别甚小,但在设计工况附近,空心叶轮风扇的气动噪声明显低于原型风扇。研究结果可为空心叶轮轴流式风机的设计、选型以及结构优化提供依据。     

Increasing flow efficiency of high-pressure and low-pressure steam turbine stages from numerical optimization of 3D blading

3D blading of a high-pressure and low-pressure steam turbine stage is optimized using Nelder–Mead method of deformed polyhedron. Values of the minimized objective function, i.e. stage losses with the exit energy are found from 3D viscous compressible flow computations, including turbulence effects. Among the optimized parameters are stator and rotor blade numbers and stagger angles, rotor blade twist angle, stator blade sweep and lean, both straight and compound. The blade sections (profiles) are assumed not to change during the optimization. There are constraints imposed on the design parameters, including the mass flow rate and stage reaction. Optimization gives designs with new 3D blade stacking lines, and with increased efficiencies, compared with the original design.     

A Study of the Movement Path for NC-Electrochemical Machining of an Integral Impeller

Aiming at machining an integral impeller used by an aero-engine by NC-Electrochemical Machining (NC-ECM),we first describe the fitting of a distorted blade surface with a ruled surface. Then a four-axis NC-electrochemical machining process is analyzed and the movement of the impeller is studied by using an equivalent open-loop plane motion link,and every program segment's feed displacement of three axes is calculated by analytical solution. Through comparing two results which are obtained,respectively,from analytical solution and experimental result,the comparative effectiveness has proved that the analytical solution is useful in calculating the feed displacement. The study is helpful for the programming of the machining process.     

矿用对旋式轴流局部通风机噪声特性实验研究

对四种对旋式轴流局部通风机的噪声特性进行了实验研究,获得了风机噪声频谱曲线和A声级随工况变化曲线,详细分析了离散噪声的频谱特性,发现对旋风机Ⅰ级叶轮通过频率（BPF1）及两级叶片相互作用频率（BIF）对应噪声是对旋风机的主要离散噪声源。这为对旋式轴流通风机的降噪提供了有益参考。     

无壳风机导流装置的模拟与试验研究

利用Fluent软件对无壳风机的内部流场和压力场进行模拟分析,得出气流在叶轮出口处由于截面突然扩大,压力损失较大,是造成无壳风机效率低下的主要原因。为改善这一缺陷,设计多种导流方案进行数值计算,并在此基础上进行风机性能的对比试验。试验结果表明,安装导流装置(方案2)后风机的性能得到显著提升,全压效率由原先的69.4%提升至80%左右。另外,在进行导流流道设计时,导流板的曲率及流道流通截面的扩张速度不应太快,否则容易发生边界层分离而使得导流板的导流扩压性能下降。导流板的安装间隙也不应过大,随着安装间隙的增大,风机的出口压力降低,风机效率下降。