1、<p><b>　　英文原文</b></p><p>　　Auto-testing system for fan performance based</p><p>　　on virtual instrumentation technology</p><p>　　Abstract: In accordance with the pr

2、esent status of measurement of fan performance with burdensome in labors, low inaccuracy and backward in testing method, auto-testing system for fan performance based on Virtual Instruments(VI)technology was developed. T

3、he system integrated sensor technology, computer technology and measurement technology.As a result, the system can not only automatically acquire, process testing data and express the final results in suitable forms but

4、also control and adjust d</p><p>　　Key words: fan; performance testing; auto-testing; virtual instrumentation; data processing</p><p>　　1 Introduction</p><p>　　The parameters of fan

5、: flux, pressure, power an deficiency not only decide working performance but also are the basis of selecting and using blower for people. Because of the blower theory being not perfect, performance testing is the main m

6、ethod of acquiring these parameters. Moreover, the testing is important for testing products and designing new products. In China, traditional fan performance testing is always done manually or by single chip which has m

7、any shortages including lower precision</p><p>　　Therefore, according to the demands of modern times experiment technique, an automatic test and analysis system for fan performance based on virtual instrumen

8、tation tool Lab Windows/CVI was designed in this paper. Combined sensor technology, computer technology and testing technique, the virtual instrumentation (VI) technology makes the most use of intelligence of computer to

9、 thoroughly break down the mode that the traditional instruments are defined by the manufacturers, however the users can n</p><p>　　As a result, the system can not only automatically acquire, process testing

10、 data and express the final results in suitable forms but also control and adjust different working loads. The whole system is friendly in interface, easy in operation and complete in functions. The experiment results ha

11、ve shown that the stability of the experiment process has increased, the reading error was avoided and the measurement accuracy and experiment efficiency were improved. The system has been widely applied t</p><

12、;p>　　2 Hardware design of the system</p><p>　　Hardware of this system, which is the basis of signal acquisition, conversion, enhance and processing, consists of fan, motors, wind pipe, sensors, computer,

13、data acquisition board, frequency conversion governor, etc. The block diagram of system structure is shown in Fig.1.</p><p>　　Among those components, computer and plug-in DAQ board play an important role in

14、the system. With the high performance DAQ board, not only data acquisition, A/D conversion but also frequency control, step motor control etc are realized. Considered of the technical indexes such as sampling frequency,

15、accuracy, A/D & D/A conversion rate, resolution, the DAQ board PCI-6024E from National Instruments (U.S.A), with which 200 ks/s, 12-bit performance on 16 single-ended analog inputs can be got up to, </p><p

16、>　　The fan parameters: flux, static pressure, torque and rotation speed are measured by corresponding sensors including differential pressure transmitter ( BC69 type, accuracy is FS ), static pressure transmitter (JYB

17、 type, accuracy is 1%FS), and torque & rotate speed sensor ( AKC-205 type, accuracy is 0. 3%FS). The sensor outputs are all standard current signal with 4~20 mA. To meet the DAQ board input signal type and range, 0 ~

18、 5 V voltage signals are achieved from 4~20 mA current signals by an i</p><p>　　Through the analog output channel on 6024E, 0~5 V voltage signal which is corresponding on 0~50 Hz of AC frequency, are sent ou

19、t to control frequency converter (FR-A540-1.5K-CH type, MITSUDISHI, Japan). Then, the fan speed changes with variable voltage.</p><p>　　The regulating unit of working status, which is designed by the authors

20、, is the rotating baffle structure composed of round baffle, shaft coupling, creeper gear and step motor etc. (See the Fig.2). This kind of structure can not only realize the auto- control but also is small and flexible.

21、 Three digital I/O port on the 6024E are used to send out three- phase pulse to control the rotation angle of step motor. The step motor drives the round baffle through the creeper gear to revolve inside the w</p>

22、<p>　　To insure the measurement accuracy, several anti-interference means are adopted such as differential inputs of signals to eliminate the common mode interference, good earth of signal line and instruments, dig

23、ital filtering technology in software.</p><p>　　3 Software design of the system</p><p>　　3.1 Data processing</p><p>　　Data processing in this system includes three aspects: processi

24、ng acquired signals to weed out various disturbing signals; using hydrodynamics formulas to calculate performance parameters of fans; fitting performance parameters based on least square method to draw performance curves

25、 of fans.</p><p>　　3.1.1 Calculation of performance parameters</p><p>　　Refer to the national standard GB1236-85, Aerodynamics performance test procedure of ventilator, the ventilator performanc

26、e testing of the discharge outlet is achieved. The fan performance parameters are calculated as follow so:</p><p>　　where is the aperture of restriction orifice; is the flow coefficient;εis the gas expansion

27、 coefficient;ρis the gas density of fan outlet;Fit the torque between motor and fan;nis the rotation speed of motor;pst is the static pressure;Pd is the kinetic pressure;Ais the area of wind pipe;vis the speed of the air

28、flow;ηis the available output.</p><p>　　3.1.2 Performance curve fitting</p><p>　　There are many curve fitting methods such as exponential fitting, orthogonal polynomial fitting . The least squar

29、e method is adopted to fit performance parameters because the characteristic curve of fan is mostly parabola. What is called "least square method" is statistically processing the observed values from experiment

30、s to make desired value of observation equal to its theoretical value and rectify the observed value.</p><p>　　Using the function Polynomial that is in the advanced analysis library of Lab Windows/CVI, the p

31、erformance curve fitting was completed. The format of function Polynomial is as follows:Polynomial(double x[],double y[],int n,int order, double z[],double coef[],double*mse)</p><p>　　The purpose of this fun

32、ction is to find the coefficients that best represent the polynomial fit of the data points (x,y) using the least squares method. Poly Fit obtains the its element of the output array and mean squared error ( mse ) using

33、the following formula: </p><p>　　With this function the flux-whole pressure curve, flux-static pressure curve, and flux-efficiency curve can be achieved.</p><p>　　3.2 Structure of the software&l

34、t;/p><p>　　The software is developed by Lab Windows/CVI which is an integrated ANSI C environment for engineers and scientists creating virtual instrumentation applications. With integrated I/O libraries, analy

35、sis routines, and user interface tools, Lab Windows/CVI delivers everything you need for building advanced test and measurement systems. Based on modular design method of program, 8 modules are designed in this system:&

36、lt;/p><p>　　(1) Basic parameters setting: user can key in the fan type and environmental parameters including atmospheric temperature, humidity and pressure in this module.</p><p>　　(2) Data acquis

37、ition and control parameters setting: in this module, the sampling channel, control channel, sampling rate, signal input/output limit etc</p><p>　　(3) Main control station: this module is the main interface

38、for operators. The visualized controls, such as power switch, testing start switch, operating mode selecting slide, fan speed selecting slide, and real-time numeric &waveform display of signals, are delivered in the

39、front panel for user operating this system conveniently.</p><p>　　(4) Data processing: in this module, not only original data but also calculated data including flux, efficiency, power and total pressure can

40、 be shown in numeric and waveform form. Moreover, based on least square method the fan performance curve can be fitted with free selected fit module.</p><p>　　(5) Test report: after test, operators can achie

41、ve the test report including grid or graph type of test dada in this module. Also, data saving, printing, exporting, importing etc are all realized.</p><p>　　(6) History query: according to the test number a

42、nd fan type, users can find history records they need with numeric or graph type documents in this module. Thus, a needed test report including fan performance curve can be displayed and printed.</p><p>　　(7

43、) Experimental simulation: a visual flash film is designed for operator to know the operating procedure well.</p><p>　　(8) System help: using the hyper text technology, the system help on line is built which

44、 consists of three parts, namely, fan performance test system overview, background knowledge and operating instruction.</p><p>　　In conclusion, the software system has key functions as follows: auto-acquirin

45、g parameters of fan performance, adjusting the rotating speed and flux of blower, auto-generating record of testing and performance curve, moreover, the software can also display, save and print these signals in graphic

46、and numeric form. The whole system is friendly and convenient for operating.</p><p>　　4 Experiment of the system</p><p>　　Take the centrifugal blower (4-72 type) for testing example in laborator

47、y, the performance testing experiment was made with this system. As shown in Fig.3, each point is the numerical value of test signal, and that connected line is the performance fitting curve based on least square method.

48、 Compared with handwork which was done at the same time, the two test results are nearly equal and the accuracy can completely meet the needs of national standard</p><p>　　5 Conclusion</p><p>　　

49、From all above, the whole system has friendly functions, which can be used widely in scientific research institutes and factories. This system improves the stability of testing process, avoids the error of reading, calcu

50、lation and result caused relative data can not be recorded at the same time with test artificially. As a result, the precision an efficiency of testing is largely improved. It meets the need of scientific production and

51、auto-management modern industry. </p><p><b>　　中文譯文</b></p><p>　　基于虛擬儀器技術的風機性能自動測試系統(tǒng)</p><p>　　摘 要：我國風機性能檢測多以手工為主，存在試驗手段落后，勞動量大和測試結果不準確等缺點,采用先進的虛擬儀器技術，將傳感器技術、計算機技術和測試技術結

52、合起來，建立了基于虛擬儀器技術的風機性能自動測試系統(tǒng)，實現(xiàn)了試驗數(shù)據(jù)的自動采集、風機轉速的自動調節(jié)、風機運行工況的自動控制、試驗數(shù)據(jù)的正確處理及性能曲線的自動繪制。整個系統(tǒng)具有界面友好、操作方便、功能齊全等優(yōu)點。試驗結果表明本系統(tǒng)增加了試驗過程的穩(wěn)定性，避免了人為的讀數(shù)誤差、計算誤差以及相關數(shù)據(jù)不能同時記錄所引起的試驗結果偏差，提高了測試精度和試驗效率。可廣泛應用于科研院所和風機生產廠家，具有較高的推廣應用價值。</p>

53、<p>　　關鍵詞：風機；性能試驗；自動測試；虛擬儀器；數(shù)據(jù)處理</p><p><b>　　1 介紹</b></p><p>　　流量，壓力，功率和效率等參數(shù)不僅決定工作績效，也決定了工業(yè)生產的正常運作。由于風機理論不夠完善，大部分依賴于狀態(tài)試驗獲取這些參數(shù)。此外，測試最重要的是檢驗產品和創(chuàng)新設計產品。在中國，傳統(tǒng)的風機性能測試是經(jīng)常手動操作傳統(tǒng)儀器從而獲

54、取參數(shù)，其中有許多不足，包括：精度不高、勞動強度大、不完善的用戶界面，等等。</p><p>　　因此，根據(jù)用戶的需求和現(xiàn)代時代實驗技術的發(fā)展，自動測試及分析風機性能系統(tǒng)應運而生。組合傳感器技術，計算機技術和測試技術，虛擬儀器儀表技術的結合使得人們可以用最普遍的方法使用智能測試儀器，徹底打破傳統(tǒng)技術由制造商制定用戶不能改變的的模式。與此同時，給用戶提供了一個空間，以發(fā)揮他們的能力和想象力不足。它是用戶，而不是制造

55、商，他們根據(jù)個人需要，他們可以設計自己的儀器系統(tǒng)。在虛擬儀器系統(tǒng)，硬件只是提供了一個解決方案，以輸入和輸出的信號為主的軟件是整個系統(tǒng)的關鍵。任何用戶可以根據(jù)需要修改軟件，增加或減少軟件的功能和軟件的儀器系統(tǒng)。</p><p>　　因此，該系統(tǒng)不僅可以自動采集、加工、試驗數(shù)據(jù)，并以適當?shù)男问斤@示最后結果，而且也控制和調整不同的工作負載。整個系統(tǒng)是具有完善的界面，易操作，并很好地完成功能。實驗結果表明，穩(wěn)定性試驗過程

56、中增加了，讀數(shù)誤差是可以避免和測量精度和實驗效率得到了改善。該系統(tǒng)已廣泛地應用于許多范生產廠家和科研單位。</p><p><b>　　2硬件系統(tǒng)的設計</b></p><p>　　硬件是這個系統(tǒng)的基礎。包括風扇，電機，風管，傳感器，計算機，數(shù)據(jù)采集板，頻率轉換器等。</p><p>　　虛擬儀器測試系統(tǒng)的硬件通常包括傳感器、信號采集、信號調理

57、、等I/O接口設備和通用計算機。計算機一般是PC機或工作站，是整個硬件的核心，；傳感器則是測試系統(tǒng)獲取外界信息的通道；I/O接口設備則采集、放大、A/D、D/A轉換被測信號等。</p><p>　　LabVIEW獲取數(shù)據(jù)的方法是通過對I/O接口設備的驅動完成的。虛擬儀器系統(tǒng)中，I/O接口設備主要是數(shù)據(jù)采集板。通過數(shù)據(jù)采集板獲取數(shù)據(jù)在虛擬儀器中又稱為PC一DAQ(Data Acquisition數(shù)據(jù)采集)式儀器。&

58、lt;/p><p>　　數(shù)據(jù)采集板作為儀器系統(tǒng)硬件的主要組成部分，是外界電信號與PC機之間的橋梁。它不僅具有信號傳輸?shù)墓δ?，還具有信號轉換和譯碼的功能。</p><p>　　風機工況調節(jié)的過程：由DAQ卡上的脈沖輸出口輸出脈沖信號加于數(shù)字電路板，控制步進電機的步進角度、正反轉及步進速度；數(shù)字電路板用于脈沖分配和步進電機的驅動；將減速器加于步進電機與旋轉擋板之間，用于防止風機運行過程中由于風力過

59、大使擋板產生轉動。通過編程，控制脈沖信號的個數(shù)和正反轉信號，當用戶發(fā)出指令改變風機運轉工況時，PC機通過DAQ卡輸出電壓信號，此電壓信號再經(jīng)過電路轉換，驅動步進電機使其轉過設定的角度，控制旋轉擋板的轉動，這樣就實現(xiàn)風機由工況1到工況10的調節(jié)，從而實現(xiàn)了流量的調節(jié).</p><p>　　該部件的工作狀況制定，這是由作者設計制定的，是旋轉擋板結構組成的輪擋板、聯(lián)軸器、齒輪和步進電機等（參見圖1），這種結構不僅可以實

60、現(xiàn)自動控制，而且也有小而靈活的優(yōu)點。</p><p>　　為實現(xiàn)風管進口氣流流量的調節(jié)，即風機工況的調節(jié)，本系統(tǒng)設計一旋轉擋板裝置。旋轉擋板的結構簡圖如圖1所示。在風管進口處安裝一圓形擋板，步進電機通過減速器帶動圓形擋板的轉動，實現(xiàn)擋板與風管進口處孔隙的變化，即實現(xiàn)流量的變化。風機工況調節(jié)的過程：由DAQ卡上的脈沖輸出口輸出脈沖信號加于數(shù)字電路板，控制步進電機的步進角度、正反轉及步進速度；數(shù)字電路板用于脈沖分配和

61、步進電機的驅動；將減速器加于步進電機與旋轉擋板之間，用于防止風機運行過程中由于風力過大使擋板產生轉動。通過編程，控制脈沖信號的個數(shù)和正反轉信號，當用戶發(fā)出指令改變風機運轉工況時，PC機通過DAQ卡輸出電壓信號，此電壓信號再經(jīng)過電路轉換，驅動步進電機使其轉過設定的角度，控制旋轉擋板的轉動，這樣就實現(xiàn)風機由工況1到工況10的調節(jié)，從而實現(xiàn)了流量的調節(jié)，</p><p><b>　　圖1</b>&

62、lt;/p><p><b>　　3 軟件系統(tǒng)的設計</b></p><p><b>　　3.1數(shù)據(jù)處理</b></p><p>　　數(shù)據(jù)處理在這個系統(tǒng)中包括三個方面：處理和清除種種不理想的后期信號；利用流體力學計算公式性能參數(shù)的精確度； 基于最小二乘法提取性能曲線的精確度并擬合性能參數(shù)。</p><p>

63、;　　3.1.1計算性能參數(shù)</p><p>　　在風機狀態(tài)試驗臺上由傳感器測得的試驗數(shù)據(jù)包括壓差、靜壓、扭矩等信號，而風機狀態(tài)參數(shù)包括流量、全壓、靜壓、功率、效率等數(shù)值，所以試驗測得的數(shù)據(jù)必須經(jīng)過計算、整理才能得到風機狀態(tài)參數(shù)值，以下為狀態(tài)參數(shù)計算公式：</p><p><b>　　體積流速</b></p><p><b>　　軸功

64、率</b></p><p><b>　　總壓力：</b></p><p><b>　　效率的總壓力：</b></p><p>　　3.1.2性能曲線擬合</p><p>　　關于曲線擬合的方式有許多種，如指數(shù)擬合、正交多項式擬合以及切比雪夫擬合等，選用何種方法，應根據(jù)原始數(shù)據(jù)所描繪的圖形

65、來決定。對于風機，由于其特性曲線的形狀多為拋物線型，所以本文采用最小二乘法原則來擬合狀態(tài)參數(shù)。所謂最小二乘法就是用數(shù)學統(tǒng)計的方法處理試驗觀測值，使試驗觀測值的期待值等于他的理論值，達到對觀測值的校正。</p><p>　　用最小二乘法是在分析圖書館的Lab Windows / CVI中，性能曲線擬合完成。格式函數(shù)具體內容如下：</p><p>　　要表達整個壓力曲線和通量靜態(tài)壓力曲線的關系

66、，流量-效率曲線可以達到這個效果。</p><p><b>　　3.2軟件的結構</b></p><p>　　Lab Windows / CVI是一個綜合性虛擬儀表軟件，該軟件是由Lab Windows / CVI的ANSI C環(huán)境工程師和科學家創(chuàng)造。在這個系統(tǒng)中，Lab Windows / CVI提供您所需的一切，如集成的I / O 圖書館、分析套路和用戶界面的工具

67、，為建設先進的測試和測量系統(tǒng)?；谀K化的設計方法和設計程序包括：</p><p>　　1 ）基本參數(shù)設置：用戶可以設置關鍵風扇型和環(huán)境參數(shù)，包括大氣溫度、濕度和壓力。</p><p>　　2 ）數(shù)據(jù)采集及控制參數(shù)設定： 在這個系統(tǒng)中包括采樣通道、控制通道、采樣率、信號輸入/輸出限制等。</p><p>　　3 ）主控站：這個系統(tǒng)是以主接口為運作口實現(xiàn)可視化的控制，

68、例如電源開關，作為測試起動開關，操作模式選擇幻燈片，并進行實時在線數(shù)字＆波形顯示的信號，送到在前面板上，用戶操作此系統(tǒng)可以實現(xiàn)方便交換。</p><p>　　4 ）數(shù)據(jù)處理：在本系統(tǒng)中，不是指原始數(shù)據(jù)，而是計算數(shù)據(jù)，包括流量，效率，功率和總壓能證明在數(shù)字和波形形式。此外，基于最小二乘法的風機性能曲線可裝有自由挑選合適的模塊。</p><p>　　5 ）試驗報告：試驗后，可以實現(xiàn)測試報告，其

69、中包括網(wǎng)格或圖表類型的測試網(wǎng)絡社區(qū)這個系統(tǒng)。此外，都實現(xiàn)了數(shù)據(jù)存儲、打印輸出、輸入等。</p><p>　　6 ）歷史查詢：在這個單元，根據(jù)試驗的次數(shù)和范型，用戶還可以找到歷史記錄，他們還可以設置自己需要的數(shù)字或圖形文件類型。因此，需要測試報告，其中包括風機性能曲線的展示和打印。</p><p>　　最后，該軟件系統(tǒng)的關鍵功能如下：自動獲取性能參數(shù)，調整轉速和通量風機，自動生成記錄，測試和

70、性能曲線，此外，該軟件還可以顯示，保存和打印這些信號在圖形和數(shù)字形式。整個系統(tǒng)是完善便于操作的。</p><p><b>　　4 實驗系統(tǒng)</b></p><p>　　以離心式鼓風機（4-72型）進行全面的測試，例如，在實驗室，性能測試實驗取得了該項功能。所示圖2 ，每一個點是數(shù)值的測試信號， 并且曲線是基于最小二乘法擬合出來的。比較手工是做在同一時間內，兩個測試結果

71、幾乎是平等和準確性，可完全滿足國家標準。</p><p><b>　　圖2</b></p><p><b>　　5 結論</b></p><p>　　從所有上述情況，整個系統(tǒng)是一個很完善的界面，操作方便和全面的功能，可廣泛應用于科學科研院所及工廠等。這個系統(tǒng)提高了性測試過程的穩(wěn)定性，避免了閱讀誤差和實驗過程總數(shù)據(jù)無法真實記