出口弯管对前向离心通风机性能影响的研究

以9-26No4A型前向离心通风机为研究对象,试验和数值模拟研究了出口90°弯管在不同连接方式下风机性能的差异。结果表明,风机出口连接正转弯头或反转弯头后,均会造成风机性能的明显下降。随着流量的增大,下降趋势变大。在风机出口与弯头之间连接长度≤3.5倍当量直径的直管段时,风机性能改善微弱。正转弯头与反转弯头对风机性能的影响差别较小。     

基于叶片数和叶片出口直径的MVR高压离心风机性能改进

以机械蒸汽再压缩(MVR)系统常用的高压离心风机为研究对象,采用数值模拟方法,研究风机的气动性能,以风机性能试验验证数值计算方法的可靠性。在此基础上,重点分析叶片数和叶片出口直径对高压离心风机各项性能的影响。数值结果表明,增加叶片数和叶片出口直径均能改善风机的气动性能,叶片数取12并增大叶片出口直径的改进风机在全压和效率方面都优于原型风机。本研究结果可为MVR高压离心风机的流场分析和叶轮结构改进提供参考。     

无蜗壳风机的特性研究及应用

为不同形式的有无蜗壳风机提供了性能试验数据对比,分析了箱体结构大小及出口位置对风机性能的影响,并对该型风机的测试方法与运行特点展开分析,进而为无蜗壳风机的设计、试验及应用提供了参考依据。     

基于CFD的离心风机蜗壳优化研究

为研究离心风机蜗壳出口宽度对风机性能的影响,用solidworks建立了风机模型,并通过测试验证了模型选取的合理性。在原风机模型基础上,改变蜗壳出口宽度,对两种不同出口宽度的风机进行气动优化计算分析,优化后的模型效率提高了4.5%。研究表明:蜗壳出口宽度偏小,其流量小,压力大,效率低;蜗壳出口宽度偏大,流量大,压力小。     

一种风机性能试验进气管道的隔音装置

针对风机在运用D式试验装置进行性能试验时进气管道不易安装消声器,以免对风机流量测量产生影响而设计了一种隔音装置,在风机噪声试验时安装该隔音装置后风机整机噪声降低约13.4%;试验装置对风机的出口全压有一定的影响,出口全压最大损失约为2.3‰,该损失不会对风机性能测试产生影响,本文为风机整机噪声试验提供一定的参考,使风机噪声评估值更加准确。     

MVR高压离心风机性能分析与优化

以MVR系统常用的高压离心风机为研究对象,利用数值模拟技术对风机流场进行三维不可压缩定常流动计算,重点分析高压离心风机内部流场的分布规律,然后以风机性能试验验证数值计算方法的可靠性。在此基础上,研究叶片出口安装角度对风机气动性能的影响。数值结果表明,把叶片出口安装角由41°改为44°可以提升风机在大流量工况下的全压和全压效率。     

螺杆空压机用多翼离心风机气动性能改进

为研究多翼离心风机原型机出口风速均匀性差机理,采用CFD数值模拟技术,计算风机内部气动性能及出口风速分布规律,并通过实验验证了计算模型和计算方法的准确性。计算结果显示该风机存在内部流场紊乱、叶道内涡旋多且蜗舌处回流严重等问题,最终造成风机出口均匀性差。在保证安装接口一致的前提下,通过优化风机进口集流器、叶片结构、叶片数量、蜗壳型线及扩压器等参数,改善了进气流道以及风扇与蜗壳匹配性,有效提升风机内部气动性能,消除涡流和回流现象。同时在扩压器进气口处增加整流破涡设计,进一步改善风机出口均匀性。实验结果表明:风机出口风速差值由10m/s降低至3m/s。     

小型后向离心风机叶轮叶片出口宽度对性能的试验分析

在某些特殊场合中,离心风机除满足额定工况外,还需满足一定流量范围内的流量-压力曲线斜率要求。本文通过改变后向离心风机叶轮出口宽度,得到了满足其流量-压力曲线斜率要求的叶轮。同时分析了其他叶轮参数相同时,改变叶轮出口宽度对风机性能的影响。通过获得叶轮出口宽度对风机特性曲线的影响,为风机叶轮出口宽度的设计及实际工程中改造叶轮提供参考。     

无蜗壳风机墙出口隔板的应用研究

多个无蜗壳风机并联组合成风机墙应用时,在风机的出口方向,分别采用隔板将各个风机均布隔开或无隔板运行研究,对风机的性能影响。     

烧结机尾除尘风机性能偏差原因分析及改进

本文从系统状态及风机本体性能两个方面对现役烧结机尾除尘风机(EP风机)的性能偏差进行了详细的综合分析,并指出了该风机不足之处。通过对风机进气箱、蜗壳结构、蜗舌间隙及蜗壳出口扩压部分等部件进行了局部改造,提高了风机性能,并总结出风机改造中需要注意的三点相关问题。     

风机盘管来流场均匀化数值模拟

通过对单风机风机盘管的来流场进行数值模拟,在风机送风口风速恒定的情况下,优化传统风机盘管结构,研究结果显示,将风机风口置中安排于送风空间有利于提高来流场气流分布均匀性;将送风空间的两侧改为从风机送风口处开始的渐扩风道形式、在送风空间内增加导流片等,均可以不同程度的提高来流场气流分布均匀性,有利于提高风机盘管的换热效率。     

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.     

Numerical Study of Aeroacoustic Sound on Performance of Bladeless Fan

Aeroacoustic performance of fans is essential due to their widespread application. Therefore, the original aim of this paper is to evaluate the generated noise owing to different geometric parameters. In current study, effect of five geometric parameters was investigated on well performance of a Bladeless fan. Airflow through this fan was analyzed simulating a Bladeless fan within a 2 m×2m×4 m room. Analysis of the flow field inside the fan and evaluating its performance were obtained by solving conservations of mass and momentum equations for aerodynamic investigations and FW-H noise equations for aeroacoustic analysis. In order to design Bladeless fan Eppler 473 airfoil profile was used as the cross section of this fan. Five distinct parameters, namely height of cross section of the fan, outlet angle of the flow relative to the fan axis, thickness of airflow outlet slit, hydraulic diameter and aspect ratio for circular and quadratic cross sections were considered. Validating acoustic code results, we compared numerical solution of FW-H noise equations for NACA0012 with experimental results. FW-H model was selected to predict the noise generated by the Bladeless fan as the numerical results indicated a good agreement with experimental ones for NACA0012. To validate 3-D numerical results, the experimental results of a round jet showed good agreement with those simulation data. In order to indicate the effect of each mentioned parameter on the fan performance, SPL and OASPL diagrams were illustrated.     

抽雾风机出口管道的压力分析及结构优化

本文从风机原理及相关流体力学理论出发,分析了抽雾风机出口管道中产生负压的原因,研究了负压对风机运行的影响及负压与出口管道结构之间的关系,建立了出口管道的优化数学模型,优化了出口管道结构。     

防涡圈对离心风机性能影响的探讨

针对某离心通风机模型,研究了防涡圈对风机性能的影响。数值模拟和试验结果都说明了加装防涡圈后全压升和效率有所下降,这与以往的认知不完全一致。设计工况下,未加装防涡圈的通风机全压升比加装长防涡圈的风机高出约4%,效率高出约3%,内泄漏情况也会随防涡圈长度的增加变得严重;从内部流场可以看出,加装防涡圈减小了蜗壳内部的扩压空间,叶轮出口大尺度漩涡更加剧烈,影响了叶轮出口气流方向,并在叶轮出口产生回流现象,降低了通风机的全压和效率。因此认为对于不同压力系数和流量系数的风机,防涡圈对风机性能的影响规律是不一样的。     

Predicting the oil cooler fan performance of large-sized diesel engines by changing the outlet and torsion angles

This study analyzed how the outlet and torsion angles of an oil cooler fan in large-sized diesel engines affect the performance of the fan using a numerical analysis method. The discharge flow rate, theoretical power, and efficiency were numerically calculated at the variable outlet and torsion angles. Results showed that the discharge flow rate slightly increased with increased outlet angle, leading to increased theoretical power and efficiency. The outlet-side blade also came closer to a vertical position with smaller torsion angle for higher performance of the fan. To verify the numerical analysis results, an experiment was conducted according to AMCA Standard 210–99 and the results were compared. The performance curve of the experimental and numerical analysis results indicated about 3% error.     

轴流式通风机出口整流体性能优化

对轴流式通风机出口整流体的性能进行了试验，通过对性能试验数据的分析，再结合轴流式通风机的实际工况，提出了在实际应用中可行的轴流式通风机出口整流体的几何形状，以达到提高风机及相应管网性能的目的。     

浅谈钢筋镦粗直螺纹机械连接接头技术

阐述了钢筋机械连接接头中镦粗直螺纹连接接头的施工技术和工艺,结合某高速公路桥梁工程中钢筋镦粗连接接头的实际施工实践,介绍了该类型接头在桥梁钢筋工程施工中的具体控制措施及其应用效果,为钢筋机械连接技术的施工提供参考.     

扭曲叶片贯流风机流场及扭曲角对性能的影响研究

研究了电壁炉用贯流风机在扭曲叶片下的三维内部流场,数值比较了不同扭曲角对贯流风机出风口体积流率的影响,从而得到贯流风机叶轮在一定转速下,叶片扭曲角取60°时,风机出风口风量最大,性能最优.通过自建的贯流风机性能参数检测台,实验测试了扭曲叶片贯流风机出风口平均风速和直叶片贯流风机出风口平均风速大小,并且和数值计算结果基本吻合.为贯流风机叶片优化设计提供了重要的理论基础.     

计及尾迹宽度的轴流风机出口气流角修正方法

针对二元平面叶栅试验数据在轴流风机动叶气动计算中的局限性 ,通过将计及动叶三元效应、旋转及弯掠的损失计算模型与动叶尾迹宽度相关联 ,建立了尾迹宽度与出口气流角的几何关系 ,提出了一种有效的轴流风机出口气流角修正方法 ,该方法亦可对动叶的升力系数进行修正。