轴流式风机性能测试及分析
轴流式风机的性能测试及分析
摘 要
轴流式风机在火力发电厂及当今社会中得到了非常广泛的运用。本文介绍了轴流式风机的工作原理、叶轮理论、结构型式、性能参数、性能曲线的测量、运行工况的确定及调节方面的知识,并通过实验结果分析了轴流式风机工作的特点及调节方法。 关键词：轴流式风机、性能、工况调节、测试报告
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轴流式风机性能测试及分析
目 录
1绪论
1.1风机的概述·····························································4 1.2风机的分类·····························································4 1.3轴流式风机的工作原理···················································4
2轴流式风机的叶轮理论
2.1概述··································································4 2.2轴流式风机的叶轮理论··················································4 2.3 速度三角形····························································5 2.4能量方程式·····························································6
3轴流式风机的构造
3.1轴流式风机的基本形式···················································6 3.2轴流式风机的构造·······················································7
4轴流式风机的性能曲线
4.1风机的性能能参数·······················································8 4.2性能曲线······························································10
5轴流式风机的运行工况及调节
5.1轴流式风机的运行工况及确定············································11 5.2轴流式风机的非稳定运行工况············································11 5.2.1叶栅的旋转脱流·······················································12 5.2.2风机的喘振···························································12 5.2.3风机并联工作的“抢风”现象·············································13 5.3轴流式风机的运行工况调节··············································14 5.3.1风机入口节流调节·····················································14 5.3.2风机出口节流调节·····················································14 5.3.3入口静叶调节·························································14 5.3.4动叶调节·····························································15 5.3.5变速调节·····························································15
6轴流风机性能测试实验报告
6.1实验目的······························································15 6.2实验装置与实验原理····················································15 6.2.1用比托静压管测定质量流量 6.2.2风机进口压力 6.2.3风机出口压力
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轴流式风机性能测试及分析
6.2.4风机压力
6.2.5容积流量计算
6.2.6风机空气功率的计算 6.2.7风机效率的计算 6.3数据处理······························································19 7实验分析·······························································27
总结····································································28 致谢词··································································29 参考文献································································30
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轴流式风机性能测试及分析
主
要
符
号
a?p?
p-------------------------------------------------------------------------------测点平均静压?p? ?p----------------------------------------------------------------------------测点平均动压?p?
pa-------------------------------------------------------------------------------当地大气压
eamaqm-------------------------------------------------------------------------------平均质量流量?kgs? -----------------------------------------------------------------------------风机入口全压
ppsg1sg2ppFCSFCQ?p?
----------------------------------------------------------------------------风机出口全压?p? ----------------------------------------------------------------------------风机全压?p? ---------------------------------------------------------------------------风机静压?p? ------------------------------------------------------------------------------体积流量?ms?
aaaa3V-------------------------------------------------------------------------------流体平均流速?ms?
pe-----------------------------------------------------------------------------风机有效功率?KW? P
a
-----------------------------------------------------------------------------轴功率?KW?
00?-------------------------------------------------------------------------------风机效率??
n-------------------------------------------------------------------------------风机转速?rmin?
L------------------------------------------------------------------------------平衡电机力臂长度（m） G------------------------------------------------------------------------------风机运转时的平衡重量（N）
G0----------------------------------------------------------------------------风机停机时的平衡重量（N）
D------------------------------------------------------------------------------风机直径（m） ?------------------------------------------------------------------------------流量系数 ?-------------------------------------------------------------------------------膨胀系数
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轴流式风机性能测试及分析
1绪论 1.1风机的概述
风机是将原动机的机械能转换为被输送流体的压能和动能的一种动力设备其主要作用是提高气体能量并输送气体。风机的工作原理与轴流风机透平压缩机基本相同，只是由于气体流速较低，压力变化不大，一般不需要考虑气体比容的变化，即把气体作为不可压缩流体处理。
1.2风机按压力分类
按风机工作压力（全压）大小分类
①风扇 标准状态下，风机额定压力范围为p?98Pa(10 mmH2O）。此风机无机壳，又称自由风扇，常用于建筑物的通风换气。
②风机 设计条件下，风机额定压力范围为98Pa?p?14710Pa(1500 mmH2O)。一般风机均指通风机而言，也是本章所论述的风机。通风机是应用最为广泛的风机。空气污染治理、通风、空调等工程大多采用此类风机。
③鼓风机 工作压力范围为14710Pa?p?196120Pa。压力较高，是污水处理曝气工艺中常用的设备。
④压缩机 工作压力范围为p?196120Pa，或气体压缩比大于3.5的风机，如常用的空气压缩机。
1.3轴流式风机的工作原理
轴流式风机得名于流体从轴向流人叶轮并沿轴向流出。其工作原理基于叶翼型理论：
气体由一个攻角。进入叶轮时，在翼背上产生一个升力，同时在翼腹上产生一个大小相等方向相反的作用力，该力使气体排出叶轮呈螺旋形沿轴向向前运动。同时，风机进口处由于压差的作用，气体不断地被吸入。
对动叶可调轴流式风机，攻角越大，翼背的周界越大，则升力越大，风机的压差就越大，而风量越小。当攻角达到临界值时，气体将离开翼背的型线而发生涡流，导致风机压力大幅度下降而产生失速现象。
轴流式风机中的流体不受离心力的作用，所以由于离心力作用而升高的静压能为零，因而它所产生的能头远低于离心式风机。故一般适用于大流量低扬程的地方，属于高比转数范围。
轴流风机右图为轴流式泵与风机的示意图，当原动机驱动浸在工质中的叶轮旋转时，叶轮内流体就相对叶片作用一个升力，而叶片同时给流体一个与升力大小相等方向相反的反作用力，称为推力，这个叶片推力对流体做功使流体能量增加。
2轴流式风机的叶轮理论 2.1概述
轴流式通风机的性能特点是流量大，扬程(全压)低，比转数大，流体沿轴向流入、流出叶轮。其结构特点是：结构简单，重量相对较轻。因有较大的轮毂动叶片角度可以作成可调的。动叶片可调的轴流式通风机，由于动叶片角度可随外界负荷变化而改变，因而变工况时调节性能好，可保持较宽的高效工作区。
2.2轴流式通风机的叶轮理论
2.2.1翼型和叶栅的概念
由于轴流式通风机的叶轮没有前后盖板，流体在叶轮中的流动，类似飞机飞行时，机翼与空气的作用。因此，对轴流式通风机在研究叶片与流体之间的能量转换关系时，采用了机翼理论。为此下面介绍翼型，叶栅及其主要的几何参数。
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轴流式风机的性能测试及分析
