毕业论文（设计）基于Matlab 和VB 混编拟合风机性能曲线的可视化研究[J]25451.doc

基于Matlab和VB混编拟合风机性能曲线的可视化研究 王松岭 张 磊/ 华北电力大学张敬辉/ 三河发电有限责任公司 摘要：采用Matlab和VB混编技术，编制了风机性能曲线拟合软件，实现了风机性能曲线拟合的可视化。结合实例给出了G4-738D型离心通风机变转速时的性能曲线，并对拟合结果进行了误差分析，拟合误差在1%之内。软件易于操作，界面友好，精确度高。关键词：离心式通风机；性能曲线；Matlab；VB；ActiveX中图分类号：TH432；TP39 文献标识码：B文章编号：1006-8155（2007）06-0059-03The Visualization Study on Fitting Characteristic Curve of Fan Based on Programming with Matlab and VBAbstract: In this paper, the visualization of fitting characteristic curve of fan is realized through programming the fitting software of fan characteristic curve based on programming with Matlab and VB. It presents the characteristic curves of G4-73No.8D centrifugal fan with different rotational speed and analyzes the fitting error that is below 1%. The software is easy to use and has the function of amity interface and high accuracy. Key words: centrifugal fan; performance curve; Matlab; VB; ActiveX0 引言火力发电厂中风机的运行状况直接关系到电厂的安全、经济运行。在选择风机时，一般把运行工况点控制在性能曲线的高效区内，以获得较好的经济性。利用性能曲线还可以分析风机内部的流动情况，积累资料，找出规律，作为设计和修改新老产品的依据，也可以作为相似设计的基础1。由于对叶轮内的各项损失尚不能用分析方法精确地进行计算，使得风机的性能曲线也就不能用分析方法精确地计算出来，通常是由试验方法求得。通过风机性能试验得到风机在不同流量时对应的风机全压、轴功率和效率值，利用数据拟合方法得到风机性能曲线2-3。Visual Basic是由微软公司开发的在Windows操作平台上的主力编程语言之一，它避开了C+编程过分繁琐和抽象的缺点，语言容易上手，界面容易设计，但是对于数值计算方面其能力欠佳4。而Matlab语言可以提供与矩阵有关的强大的数据处理和图形显示功能，为软件开发人员在程序编制过程中实现数值计算和图形显示新添了又一行之有效的开发平台。但Matlab的界面功能比较弱，给友好界面的开发应用或软件演示系统带来不便。为了提高工程计算软件的开发效率和质量，鉴于上述两个软件的各自特点，可采取把VB可视化功能和Matlab计算功能相结合的办法，充分利用各自的特点进行混合编程，即用VB来设计界面作为主程序，调用Matlab编写的子程序，以此开发出高质量、高性能的软件系统5。其实现的过程有多种，本文采用ActiveX自动化技术实现VB调用Matlab，编制了基于最小二乘法的风机性能曲线拟合软件。1 基本原理1.1 最小二乘法对于给定的数据，i=0,1,，m，其拟合函数为 （1）此时正规方程组为 （2）式中： ， ; ，。由式（2）中解出，带入式（1）中，即得拟合函数。由该函数可绘曲线。1.2 比例定律当已知风机转速为时的性能曲线，欲求转速为时的性能曲线时，其相似工况点的参数应该满足式（3）式（5）。 （3） （4） （5）式中脚标“0”代表样本条件。所以应用比例定律（在转速相差不超过20%情况下）可以实现如下功能：（1）根据已知风机的试验性能曲线推算与该风机相似的风机的性能曲线；（2）根据风机在某一状态下的工作参数，换算成其他工作状态下的工作参数（在密度不变的情况下，仅限于转速改变），即理论绘制风机的性能曲线。具体的换算过程见文献1。2 ActiveX自动化技术实现VB调用MatlabActiveX自动化协议是一种允许一个应用程序(控制端)去控制另一个应用程序(服务器端)的协议。由于VB支持ActiveX自动化控制端协议，Matlab支持ActiveX自动化服务器端协议，通过建立VB和Matlab之间的ActiveX 自动化连接，就可实现VB应用程序中调用Matlab的命令、向Matlab传送或从Matlab接收矩阵数组6。2.1 创建ActiveX对象在Windows注册表中，Matlab的ActiveX对象名为“Matlab.Application”。在VB应用程序中创建ActiveX对象的具体步骤如下：Dim Matlab As ObjectSet Matlab=CreateObject( “Matlab.Application”)2.2 ActiveX对象的操作在VB应用程序中创建了Matlab的ActiveX对象后，就可以使用这个对象所包含的各种方法来实现对Matlab的调用。Matlab.Application对象主要含有3种方法，它们是Execute、GetFullMatrix和PutFullMatrix。主要使用Execute方法，其语法为BSTR Execute(BSTR Command)，其中参数Command为要Matlab执行的命令字符串；运行结果以字符串返回，图形则以Matlab图形窗口的形式显示。3 实例3.1 试验数据以G4-738D型离心通风机为例，通过风机性能试验，得到其轴向导流器开度为零、风机转速为1450r/min时的流量、全压数据，见表1。基于比例定律，编程可得到风机转速为1350r/min、1250r/min、1150r/min、950r/min时的流量和全压数据。表1 G4-738D离心通风机流量与全压值（n=1450r/min）测点全压/Pa进口流量/（m3/s）11270.857.1621390.496.8931608.186.2241851.375.24519713.8361998.462.4472020.031.5182018.071.353.2 实现步骤及主要程序语句（1）打开 Visual Basic 6.0程序窗口，并在窗口建立相应的控件；（2) 在VB中调用Matlab，在窗口事件中输入原始数据；Public objMATLAB As ObjectSet objMATLAB = CreateObject(“Matlab.application”)（3) VB中调用Matlab，用Matlab实现拟合计算，并返回结果；strCommand = "n=" & Str(intLevel) & "x="For i = 1 To intNumstrCommand = strCommand & Str(x(i) & " " Next istrCommand = strCommand & "y="待添加的隐藏文字内容3For i = 1 To intNumstrCommand = strCommand & Str(y(i) & " " Next istrCommand = strCommand & "" strCommand = strCommand & "format long;polyfit(x,y,n)"Text7 = objMATLAB.execute(strCommand) （4）利用相似定律，编程获得在其他转速下性能曲线表达式的系数；（5）利用得到的计算数据在VB中绘图。3.3 程序界面与性能曲线图程序界面与风机转速为1450r/min、1350r/min、1250r/min、1150r/min、950r/min时的性能曲线如图1和图2。通过编程计算得到了风机在不同转速时的性能曲线表达式。如风机在1450 r/min时性能曲线表达式为 图1 程序界面 图2 变转速风机性能曲线图图2中：n0=1450r/min；n1= 1350 r/min；n2=1250 r/min；n3=1150 r/min；n4=950 r/min。3.4 误差分析以风机转速1450r/min时为例，风机流量和全压的拟合值和试验值见表2。表2 流量与全压数据（n=1450r/min）性能曲线表达式：流量/（m3/s）实际全压/Pa拟合全压/Pa误差/%7.161270.851269.950.0716.891390.491389.850.0466.221608.181621.280.8155.241851.371840.720.5753.8319711974.800.1922.441998.462000.350.0951.512020.042015.560.2211.352018.072021.080.149由表2中数据可知，风机性能曲线拟合的误差在1%以内，符合一般情况下风机性能曲线的拟合误差要求。如果需要提高拟合曲线的精度，可增加测试点数目，并且保证选择的测试点能最好地反映风机工作时的主要性能。4 结论本文基于最小二乘法，采用Matlab与VB混编，编制了风机性能曲线拟合软件，实现了风机性能曲线拟合的可视化。软件操作简单、易于修改，具有通用性。采用Matlab处理风机性能试验得到的试验数据，提高了计算的精度与速度；利用Matlab与VB的混合编程，得到不同转速时风机性能曲线的表达式和曲线图，并对拟合数据进行了误差分析，结果显示，拟合误差在1%以内，符合精度要求。参 考 文 献1 安连锁.泵与风机M.北京：中国电力出版社，2001：40-41.2 傅松，王松岭，杨永钊.正交函数法在拟合通风机性能曲线中的应用J.风机技术，2003（5）：10-12.3 王军，吴立强.用B样条曲线拟合通风机性能曲线J.通用机械，2006（1）：84-86.4 潘小轰.Visual Basic 6.0程序设计基础教程M.北京：冶金工业出版社，2001.5 李永曦，陶伟莲，关立行.在VB 60中调用MATLAB程序J.微机发展，2004，1（14）：88-89.6 张宏立，李拮.基于ActiveX机制的VB与MATLAB数据交换J.新疆大学学报(自然科学版)，2004，21（2）：191-193.Editor's note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced with CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the world's first satellite - Sputnik. I also missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space race has renewed my childhood dreams to reach for the stars.As a meteorologist, I've still seen many important weather and space events, but right now, if you were sitting next to me, you'd hear my foot tapping rapidly under my desk. I'm anxious for the next one: a space capsule hanging from a crane in the New Mexico desert.It's like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line "we" would be go for launch.I feel this mission was created for me because I am also a journalist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain when a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydiverWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and "capcom" (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, "Fearless Felix" will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he'll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps for the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it's not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it won't. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way I'd miss this.