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风机状态测试系统的总体设计
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风机测试来源： ASHRAE学报40 no9 35-9 S的98补充风机空气动力性能测试许多年以来人们认为对风机的性能测试的方法与规律的研究是可能而且必要的。其中第一个测试标准的推出是在1923年，它是由全国风机制造商协会与美国社会热化，并且还有风机设计工程师(ASHVE)，AMCA的前辈和ASHRAE，他们共同制定了当前ANSI/AMCA标准210-99和ANSI/ASHRAE标准51-1999，实验室测试方法为规定值扇动。ISO 5801作为美国国家标准之外，还在加拿大作为风机与飞行动力学的性能试验的国际标准。确定风扇气流容量是一般测试原则的基本量：通过一个可测量的区域指挥控制气流并且测量气流速度。 气流容量为区域的面积乘速气流的度。因为空气的流动性与区域的不确定性和因压力形状容易改变，以至于规定一个测量区域是很困难的。风速间接地被测量，一股移动的气流引起速度和空气的密度的改变从而可间接的测量空气压力。压力变化直接与空气密度和速度的平方成正比，为了使测量准确性的改善，当速度增加压力也就随之增加。风机性能是空气在通风进气口流动速率和横跨风扇的总压增量用m3/s (cfm)表示的。 输入功率是第三个参量。测试结果的准确性取决于一定数量的可变物并且不同程度对准确性有影响。AMCA有一个被检定的实验室项目。要检定实验室，测试一台特定风机在那个实验室和在AMCA实验室是必要的。 测试结果必须在+1.25%或-2.5%之内。 要达到那准确性，应密切注意所有细节，维护仪器的接近的定标都是必要的。设施类型风机，被定义成用电力驱使机器移动和改变气体的容量以获得一定能量的气体的机械设备，对风机的测试就在测试模拟装置中进行。 四个标准设施类型在表1显示标准210测试装置要确定风扇的空气动力性能，一般使用的做法是在ANSI/AMCA出版的210中的标准方法. 当使用空气作为测试气体时Anumber测试装置和演算方法是在风扇的所有类型测试系统中都可通用的，并且可以允许的灵活性的应用于其他空气能量转移的设备。在标准概述的十个测试装置中应该选择一种类型这样能合理地模拟风机设备的安装条件。基本上，常用的有四种测试装置。 这些是： 在放电输送管的皮托管横断。 在入口输送管的皮托管横断。 多喷管出口测试风室箱。 多喷管入口测试风室箱。在标准包括的其他测试装置是这些基本的类型的修改。选择适合风扇设施类型的设定是重要的。皮托导线类型设施是进行测试作业要求最低的设备，但所需的测试时间很长，因为所需较长的时间，需要多导线测量数据。喷管试验设施需要装备的是半perimanent格局，并因而费用更昂贵，但其测试的时间有很大幅度的缩短，方便进行测试。由于弹性的选择喷嘴组合相匹配的能力强，所以多喷嘴功能让许多大小扇的检验在同一设施中。出口输送管设定。一皮托导线设置是用来进行测试，在风机上安装插座槽（图2 ） 。测试释放入输送管的风扇用于出口输送管设定确定表现。取决于测量采用皮托静态管穿越管道在平面测量。矫直机是必须建立统一的流通格局和消除涡流，例如像制作tubeaxial型风扇。它可能被用来进行测试对离心式风机或轴流风机出口管道。在这个风机的设定结果被认为是设施类型B ： 自由入口，输送的出口。 一个可利用的选择是测试与模拟设施类型的入口周长和一条等效输送管直径D ： 输送的入口，输送的出口。Tubeaxial和风扇螺旋桨在风机中产生有角漩涡。为了对测试结果准确，在测试设置的选择性能测试时应该关心能使这个情况减到最小的作用。 AMCA标准210不准许测试自由的出口风机，例如推进器风扇，在皮托管横出口输送管设定。 实际上，没人对出版结果满意。当直挺器时去除漩涡，可观的能量丢失。入口输送管设定。皮托管横断设定使用在入口输送的风扇的测试(图3)。 测试从输送管的一个风扇气流用于入口输送管设定确定表现。 测量取决于表现使用横断的输送管一支空速静压管的测量皮托。 要求直挺器保证漩涡在接近通风进气口的气流不发生。在这个设定中的风机结果被认为设施类型C ： 输送的入口，自由出口。 一个可利用的选择是测试以放电输送管模仿设施类型D ： 输送的入口输送了出口。ANSIVAMCA标准210不准许测试自由的入口风机，例如推进器风扇，在一个皮托管横入口输送管设定。出口风室设定。多喷管出口风室也许被用于进行对将使用或者有或没有出口输送的供应风扇的测试(图4)。 测试风扇排风到测试风室里，也许被考虑模拟要求风机的设施提供空气给输送管系统或充满。 一个可利用的选择是测试风扇有或没有入口调节器和一条等效输送管直径模仿测试有或没有入口输送管。对于风扇的所有类型，输送或非输送，也许如此被测试。 通常，离心和轴向气流类型风扇在这个类型设施被测试。 使用出口风室，螺旋桨风扇或tubeaxial风扇也许被测试，但是风室短剖面区域必须是16倍风扇出口的区域。 这个比率是大，以便一些风扇排风在静压轻拍不反射屏幕半新forsettling的手段并且不冲击。 速度压力将给错误的静压读数。入口风室设定。多喷管入口风室也许被用于进行对将使用或者有或没有出口输送管的排气扇的测试(图5)。 从风室的测试风扇气流。 在这个设定风机表现被考虑模拟一个风扇气流的设施从输送管系统或从充满。 它也许为测试任何类型使用风扇，二者之一有或没有出口输送管。通常，推进器风扇和力量屋顶通风设备如此被测试。 这些风扇是设施类型A ： 自由入口，自由出口。 离心和轴流风机如此通常没有被测试; 然而，他们也许是，因此测试对于特别要求。基本的演算要绘制风扇空气动力性能图表，容量气流率一个必须测量数据逐点描绘在坐标图纸上一定的位置。 画光滑的曲线通过测试点代表风机性能状态(图6)。 对于这些每一个测试点，记录压力、速度、湿度和温度、功率计或瓦特的气压和扭矩被校准的电动机的输入是必要的。横皮托管演算。对于皮托管横例行试验，记录在测试输送管的速度取决于容量气流， Q。 输送管的区域在皮托管横皮托的被测量。 然后， Q =平均速度*区域面积。喷管演算。对于喷管例行试验，记录横跨喷管的降压建立气流速度使用被测量的喷嘴横截面和计算喷管系数取决于容量气流： Q =喷嘴喉部速度*喉部面积*卸料系数。每喷管的容量气流在使用中在测试期间被计算。他们的总气流率是风扇的体积流率。力量演算。力对于风扇是必需测定的，对于这个量通过使用功率计测量，或者是扭矩传感器，测量校准风机的电动机。 功率计或扭矩传感器： H= (扭矩*速度) /K，其中H是风扇力量需要的和K是在测试或扭矩读出的使用的种类的转换价值功率计。为校准风机的马达，定标数据为在测试使用的具体马达是一定的。 定标曲线必须包括瓦特输入和电动机转速对在负荷状态下或扭矩输出的输出功率。 测试风机输入功率是相同的像马达输出功率不管它是否是指挥连接或传送带控制类型风机。空气密度演算。演算取决于在测试期间的空气密度使用干球温度计温度，与在ANSI/AMCA标准包含的做法符合的湿球温度andbarometric压力210。转换测验数据工作特性取决与测试密度情况.标准规定值的目的是空气密度的转换。在这个做法，容量流依然是同样的，并且风机试验压力和校准马力对标准空气密度情况成正比。 测验数据可能被转换成匀速或是规定的测试的正常速度。匀速演算。风机的规律演算被用于计算测试结果到匀速和标准空气密度情况如下：Qc= Q(Nc/N)Ptc =Pt (Nc/N)2(dc/d)Pvc= PV(NC/N) (dc/d)Psc =Ptc -PvcHc= H(NC/N)3 (dc/d)从而有Q = volume airflow ratePt = fan total pressurePv = fan velocity pressurePs = fan static pressureH = fan power requiredN = fan speedd = fan densityc = subscript, required converted value“正常运行”速度演算。计算测试结果也许是中意的“正常运行 的速度情况。在这种情况下，测试被转换成标准空气密度情况，作为图文演示一部分，并且风扇速率必须是风机性能的一个表现数据。根据这个依据：Qc=QPtc =Pt(dc/d)Pvc=Pv(dc/d)psc = Ptc -PVcHc= H(dc/d)Nc=N评论包括在试验设备的测试的要求和类型将考虑的一些个项目建立风扇的空气动力性能只是可能的。 我们注重的测试装置几乎将模仿典型的风扇installation.AMCA出版了风扇应用指南应该选择。 它对在输送管系统安装风扇的用户是特别可贵的。 系统提出作用因素是风机性能之间的区别; 和风机安装的情况和它的试验条件。试验设备和必需的演算做法设计的具体细节可以在ANSI/AMCA标准210找到。AMCA标准220，把空气压缩向下喷成之无形门帘单位的测试方法，是概述测试性能的重要方法; 把空气压缩向下喷成之无形门帘单位的参量。 这些参量是空气容积、出口均一和速度投射。l 使用多喷管入口风室，测量空气容积气流率。 测量的气流的设定在AMCA标准210显示。 出口喷嘴或者出口叶片，把空气压缩向下喷成之无形门帘单位被指挥往什么的15度通常将被认为复制平均安装的情况的外部(图1).这种情况给用户一个规定值代表性设施。 适当的输入功率被测量完成性能准则。出口速度均从在几个皮托的一系列的最大速度规定值被计算在把空气压缩向下喷成之无形门帘单位出口附近。迅速而果断的判断选择以便给最大的变异。单位登上在测试的二表面之间。 这依顺序模仿几个单位的设施(图2)。l 速度投射演算由在几个皮托的一系列的最大速度测定值做顺流把空气压缩向下喷成之无形门帘单位出口。这个试验过程建立沿典型的单位额定的投掷(图3)顺流审查把空气压缩向下喷成之无形门帘的均一。 机040537 张新泉Fan TestingSOURCE: ASHRAE Journal 40 no9 35-9 S98 suppFan Air Performance TestingIt was recognized many years ago that rules and methods for determining fan performance were necessary.One of the first test standards was published jointly in 1923 by the National Association of Fan Manufacturers with the American Society of Heating and Ventilating Engineers (ASHVE), the predecessors of AMCA and ASHRAE respectively, who have jointly sponsored the current ANSI/AMCA Standard 210-99 and ANSI/ASHRAE Standard 51-1999,Laboratory Methods of Testing Fans for Rating. In addition to its status as an American National Standard, it is accepted in Canada and included in the international standard on fan aerodynamic performance testing, ISO 5801.The principle used to determine the fan airflow volume is basic: direct the airflow through a measurable area and measure the airflow velocity. The airflow volume equals the velocity times the area. It is not too difficult to measure an area, particularly if it is round and not too likely to change shape with pressure fluctuations. The air velocity is measured indirectly; a moving airstream generates a measurable pressure that changes with the velocity and the density of the air.The pressure varies directly with the air density and as the square of the velocity so that the measuring accuracy improves as the velocity increases.Fan performance is a statement of the air flow rate in m3/s (cfm) at the fan inlet and the total pressure increase across the fan. Input power is the third parameter.The accuracy of the test results depends on a number of variables and each affect accuracy to a different degree. AMCA has an accredited Laboratory Program. To accredit a laboratory, it is necessary to test a given fan in that laboratory and at the AMCA Laboratory. The test results must be within +1.25% or -2.5%. To achieve that kind of accuracy, it is necessary to pay close attention to all details and maintain close calibration on the instruments.Installation TypesFans, defined as power-driven machines used to move a volume of gas, are tested in setups that simulate installations. The four standard installation types are shown in Figure 1Standard 210 Test SetupsTo determine the air performance of a fan, use the procedure and methods published in ANSI/AMCA Standard 210.Anumber of test setups and calculation methods are available, permitting flexibility in testing of all types of fans or other air moving devices when using air as the test gas. The ten test setups outlined in the standard should permit selection of a design type that may reasonably simulate the fan installation conditions.Basically, there are four kinds of test setups. These are: Pitot traverse in a discharge duct. Pitot traverse in an inlet duct. Multi-nozzle outlet test chamber. Multi-nozzle inlet test chamber.The other setups included in the standard are modifications of these basic types. It is important to select a setup that fits the fan installation type.Pitot traverse type facilities require a minimum of equipment for testing purposes, but the time required to conduct a test is extensive because of the time required for the many traverse data measurements.Nozzle test facilities require equipment that is generally arranged as semi-perimanent setups and are thus more costly, but there is a considerable reduction in time to conduct a test. The multi-nozzle feature allows many sizes of fans to be tested in the same facility due to the flexibility of selecting nozzle combinations that match the fan capabilities.Outlet duct setup. A Pitot traverse setup is used to conduct tests on fans that will be installed with outlet ducts (Figure 2). An outlet duct setup is used to determine performance by testing a fan discharging into a duct. The performance is determined by measurements using a Pitot static tube for traversing the duct at the plane of measurement. A straightener is required to establish uniform flow patterns and eliminate swirl, such as that produced by tubeaxial type fans. It may be used to conduct tests on centrifugal fans or axial flow fans with outlet ducts.Fan performance on this setup is considered Installation Type B: free inlet, ducted outlet. An available option is to test with an inlet bell and one equivalent duct diameter to simulate Installation Type D: ducted inlet, ducted outlet.Tubeaxial and propeller fans produce angular swirl of the air from the fan discharge. Care should be exercised in the selection of the test setup for performance testing to minimize the effects of this condition on the test results. AMCA Standard 210 does not allow testing free outlet fans, such as propeller fans, in Pitot traverse outlet duct setups. In fact, no one would be happy with the published results.When the swirl is removed by the straighteners, considerable energy is lost.Inlet duct setup. A Pitot-traverse setup is used to conduct tests on fans that will be used with inlet ducts (Figure 3). An inlet duct setup is used to determine performance by testing a fan exhausting air from a duct. The performance is determined by measurements using a Pitot static tube for traversing the duct at the plane of measurement. A straightener is required to ensure that swirl does not occur in the airstream approaching the fan inlet.Fan performance on this setup is considered Installation Type C: ducted inlet, free outlet. An available option is to test with a discharge duct to simulate Installation Type D: ducted inlet ducted outlet.ANSIVAMCA Standard 210 does not allow testing free inlet fans, such as propeller fans,in a Pitot traverse inlet duct setup.Outlet chamber setup. Multi-nozzle outlet chambers may be used to conduct tests on supply fans that will be used either with or without outlet ducts (Figure 4). The test fan discharges air into the test chamber, which may be considered to simulate an installation requiring a fan to supply air to a duct system or a plenum. An available option is to test the fan with or without an inlet bell and one equivalent duct diameter to simulate a test with or without inlet duct.All types of supply fans, either ducted or non-ducted, may be tested in this manner. Normally, centrifugal and axial flow type fans are tested in this type facility. Propeller fans or tubeaxial fans may be tested using an outlet chamber, but the chamber cross-section area must be 16 times the area of the fan outlet. This ratio is large so that some fan discharge air does not reflect off the screens used forsettling means and impinge on the static pressure taps. The velocity pressure would give an erroneous static pressure reading.Inlet chamber setup. Multi-nozzle inlet chambers may be used to conduct tests on exhaust fans that will be used either with or without outlet ducts (Figure 5). The test fan exhausts air from the chamber. Fan performance in this setup is considered to simulate an installation of a fan exhausting air from a duct system or from a plenum. It may be used for testing any type fan, either with or without an outlet duct.Normally, propeller fans and power roof ventilators are tested in this manner. These fans are Installation Type A: free inlet, free outlet. Centrifugal and axial flow fans are not usually tested in this manner;however, they may be so tested for special requirements.Basic CalculationsTo chart fan air performance, one must measure data at selected increments of volume airflow rate and plot the calculated results on graph paper. A smooth curve is drawn through the test points to represent the fan performance (Figure 6). For each of these test points, it is necessary to record pressure, speed, dry，and wet-bulb temperatures, barometric pressure, and torque for dynamometers or watts input for calibrated electric motors.Pitot traverse calculation. For Pitot traverse type testing, the volume airflow, Q, is determined by recording the velocity in the test duct. The area of the duct at the Pitot traverse plane is measured. Then,Q = average velocity * area.Nozzle calculation. For nozzle type tests, volume airflow is determined by recording the pressure drop across the nozzle to establish airflow velocity using the measured nozzle throat area and calculating the nozzle coefficient: Q = nozzle throat velocity * throat area * coefficient of discharge.The volume airflow for each nozzle in use during the test is calculated.Their total airflow rate is the volume flow rate of the fan.Power calculation. Power required for a fan may be determined by using a dynamometer, torque sensor,or calibrated electric motor. For dynamometers or torque sensors: H=(torque * speed)/K, where H is the fan power required and K is the conversion value for the type of dynamometer or torque readout used on the test.For calibrated motors, calibration data for the specific motor used on the test must be determined. The calibration curve must include watts input and motor speed versus output power or torque output under load conditions. The test fan input power is the same as the motor output power regardless of whether it is a direct-connected or a belt-drive type fan arrangement.Air density calculation. Air density during testing is determined by calculations using dry-bulb temperature, wet-bulb temperature and barometric pressure in accordance with the procedure contained in ANSI/AMCA Standard 210.Converting Test DataPerformance data are converted from test density conditions .standard air density for rating purposes.In this procedure, the volume flow remains the same, and the fan test pressure and horsepower are corrected to standard air density conditions in direct proportion to the density ratios. Test data maybe converted to a constant speed or presented at the speed of the test as run.Constant speed calculation. The fan laws are used to calculate test results to constant speed and standard air density conditions as follows:Qc= Q(Nc/N)Ptc =Pt (Nc/N)2(dc/d)Pvc= PV(NC/N) (dc/d)Psc =Ptc -PvcHc= H(NC/N)3 (dc/d)whereQ = volume airflow ratePt = fan total pressurePv = fan velocity pressurePs = fan static pressureH = fan power requiredN = fan speedd = fan densityc = subscript, required converted value“As run” speed calculation. It may be desirable to calculate the test results to an as run speed condition.In this case, the test is converted to standard air density conditions, and the fan speed must be showvn as part of the graphical presentation. of the fan performance.On this basis:Qc=QPtc =Pt(dc/d)Pvc=Pv(dc/d)psc = Ptc -PVcHc= H(dc/d)Nc=NCommentsIt is only possible to cover a few items to be considered in the requirements of test facilities and types of tests to establish air performance of a fan. We stress that a test setup should be selected that will most nearly simulate the typical fan installation.AMCA has published a Fan Application Manual. Itis particula
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