基于小波变换的离心风机弱失速特征分析

结合实验室4—73Nd8D风机进行了旋转失速试验,将谐波小波变换引入旋转失速的研究,通过对弱失速阶段机壳压力信号的时频分析,确定了弱失速阶段的失速能量间歇现象、频率特征以及在弱失速阶段对调节作用的敏感性,从而说明离心风机的弱失速阶段是一个应该引起运行、维修人员足够重视的重要区域,这也为离心风机旋转失速的深入开展研究莫定了基础。     

基于一类改进谐波小波的离心风机旋转失速特征分析

通过对谐波小波频谱边缘突变点应用Hanning窗进行光滑处理，改善了谐波小波的时域衰减特性，并给出实现算法。通过对离心风机旋转失速的试验研究，应用改进的谐波小波时频等高线图对不同测量部位的动态压力信号进行时频分析，得出在不同导流器开度下离心风机不同的特征和弱失速区域的能量间歇现象，风机最高效率线与失速边界线比较接近，并且在导流器小开度下会出现交叉，说明弱失速区域应引起运行、维修人员足够重视。图10参8     

基于谐波小波变换的4_73风机压力侧失速特性分析

在对离心风机压力侧失速的形成机理定性分析的基础上,通过对4-73风机的实验研究,发现4-73风机存在压力侧失速现象,并采用谐波小波变换对于压力侧失速的时频特性进行了分析。在分析中,对于时域定位能力较差的正交谐波小波进行频域光滑处理,在旋转失速的分析中引入非正交谐波小波变换,分析结果证明了谐波小波变换对于离心风机旋转失速特性分析的有效性。     

离心风机的降噪与节能

为解决离心风机运行中产生的噪声与节能问题 ,通过对风机调节转速、调节风量 ,安装阻性消失器 ,将风机改为双速或变速驱动等手段进行了研究 ,指出 ,这些方法可收到节电、降噪的效果     

一起轴流式风机失速的处理及预防

基于轴流式风机失速的机理,介绍了某电厂超临界机组风烟系统一次风机并入过程中发生失速现象,分析了失速的原因,并提出了针对性的预防措施。     

基于流固耦合的离心风机叶轮动力特性分析

采用数值计算软件CFX和Ansys对离心风机叶轮进行了流固耦合模拟研究,对叶轮的强度、模态和振动特性进行了计算和分析.结果表明:考虑流固耦合作用后,风机的气动性能几乎没有变化,但是叶轮最大总变形量减小2.5％,最大等效应力增大3.6％;考虑预应力效应后,叶轮的固有频率提高,且不同阶次条件下的提高幅度不同;在稳定运行工况下,叶轮周围气流压力的主要脉动频率与叶片通过频率相同;叶轮的固有频率部分落入局部共振区域,该区域的等效应力远小于叶轮材料的疲劳极限,不会导致叶轮疲劳破坏.     

配内燃机车离心风机的设计改型

利用商业软件Fluent对配内燃机车离心风机内部气流的流动情况进行了数值模拟。模拟结果与实验结果对比表明,两者能够较好的吻合,误差在5％以下。在此基础上,对风机内部的流场分布,尤其是沿叶高方向气流的流动情况进行了分析,找到了导致风机效率较低的原因,并有针对性地对风机进行了改型。改型后的模拟结果显示,风机的效率提高了6％左右,效率提升较为明显。     

离心风机噪声的产生原因及控制

分析离心通风机噪声产生的机理，介绍几种降噪措施。     

微型离心风机内部流动的数值计算分析

针对笔记本电脑散热用微型离心风机，利用逆向工程技术获得风机叶片及其蜗壳模型，利用数值计算软件Fluent对其内部流动进行了模拟计算，并将计算得到的风机性能曲线与实验结果进行了比较，结果显示误差在8％以内，同时分析了风机内部流动情况。     

基于正交试验的离心风机多因素优化设计研究

以某离心风机效率为优化目标,选定离心风机的4个关键参数:转速、叶轮直径、出口安装角、叶轮出口宽度,基于正交试验设计法,通过CFD数值仿真计算以及对计算结果的极差法分析,得出叶轮几何参数及转速的相对最优组合模型。组合模型计算结果表明,优化后风机达到设计要求。同时,优化组合模型风机静压效率可提高4.49%,全压效率提高6.94%。该研究方法适用于具有目标明确的风机改进设计,可快速精准获得优选方案。     

Real-Time Instability Detection of Centrifugal Compressors Based on Motor Speed Measurements

Flow instability in the centrifugal compressor should be detected and avoided for stable and safe operation. Due to the popularity of electric centrifugal compressors, instability detection could be achieved by measuring motor signals instead of traditional aerodynamic signals. In this paper, the feasibility of instability detection by motor signals(i.e. rotating speed and phase current) was studied experimentally. The physical structure and control method of the electric centrifugal compressor ...     

电站离心通风机并联运行的经济性比较

针对电站中通风机大多数都是两台并联运行的状况,应用最小年费用法,对电站风机并联运行时采用的三种调节方案进行了经济性比较,对风机运行的节能具有重要的指导意义。     

Profile Scaling of Miniature Centrifugal Fans

This paper addresses issues that relate to downscaling the height of centrifugal fans for application in low profile technologies, such as the cooling of portable power electronics. The parameters studied include flow rate, pressure rise, and power consumption characteristics. The former two of these are measured using a fan characterization rig and the latter by directly measuring the power supplied to the fan. These are studied for fan diameters ranging from 15 to 30 mm with numerous profile heights between 0.3 mm and 15 mm. It is found that all of the phenomena encountered are best described in terms of fan aspect ratio. The results show that the conventional scaling laws cannot be accurately applied when blade profile alone is scaled. Indeed, the only parameter reasonably well predicted was the pressure rise attainable, but that was only accurate for fan aspect ratios greater than 0.17. Below this, the pressure rise generated reduces logarithmically toward zero. The study also reveals that no advantage is gained by using fans of aspect ratio greater than 0.3, as the maximum flow rate attainable decreases slightly above this. Overall, the scaling phenomena reported herein provide invaluable information for the future design of efficient low-profile cooling solutions that are to incorporate such fans.     

Behavior of Vaneless Diffuser Stall in a Centrifugal Compressor

The rotating stall in a centrifugal compressor with a vaneless diffuser was investigated both experimentally and numerically with focus on the effect of the internal flow field within the impeller on the diffuser stall.Through numerical analysis,the boundary layer separation at the impeller outlet was found to play an important role in the expansion and rotation processes of the diffuser stall.In particular,the expanded boundary layer separation near the hub side at the outlet of the main blade(M.B.)suction surface passage was considered to be the main cause of the expansion and rotation processes.A longitudinal vortex existed at the throat of the M.B.passage,and the mass flow rate in the M.B.passage was significantly reduced by the blockage effect.In addition,the longitudinal vortex induced the rolling up flow near the hub side at the impeller exit.Thus,the boundary layer separation expanded.     

离心压气机宽无叶扩压器旋转失速的数值研究

无叶扩压器作为离心压气机的重要部件,研究其内部旋转失速的诱发过程及机理对离心压气机无叶扩压器旋转失速的主动控制具有重要意义.利用ANSYS平台对离心压气机建模并对其旋转失速过程进行非稳态数值模拟.结果表明:离心压气机无叶扩压器旋转失速是随着流量的逐渐减小建立起来的,失速工况点位于性能曲线的负斜率区;无叶扩压器内部,低速...     

Study of Rotating Stall in a Centrifugal Compressor with Wide Vaneless Diffuser

To study the stall mechanism in a wide vaneless diffuser, a three-dimensional centrifugal compressor model was established. The numerical simulation method was used to study the fluid characteristics in a centrifugal compressor with a wide vaneless diffuser under stall conditions. The simulated results showed that the wide vaneless diffuser stall was related to the instability of the core flow. Due to the influence of the reflow, the core flows moved between the hub and shroud side and the direc...     

采用传像光纤和数字图像处理技术检测燃烧火焰

基于传像光纤和数字图像处理技术开发的锅炉燃烧器火检测装置,是近年来推出的一种新型火焰检测装置,它代表了当前世界先进水平,在大量研究工作和工业试验的基础上,这套装置已在国内３５０ＭＷ机组上投入运行并通过了技术鉴定。