【摘要】： This paper described development process of cavitation performance auto-test system on the centrifugal pump in detailly . Through serious analyzing the current trends of automatic test system and the composed schemes which always used in virtual instruments. finally set the scheme of testing system which composed by the single-chip microcomputer and serial virtual instruments Through making the study of the National Standards of GB/T3216-2005《Rotodynamic pumps-Hydraulic performance acceptance tests-Grade 1 and 2》, ascertained the Grade-2 precision as the design objectives of the auto-test systems. Based on this index,combined with the used situation,computed and chose the physical sensors,contactor, regulating valve and so on. Beside that, designed the system hardware circuitry which cores is the model of AT89C51ac2 single-chip microcomputer including the display interface hardware circuit, serial communications interface circuits, contact driver circuit and so on. A testing system should have testing software as supporting based on the designed hardware, so, the softs of snigle-chip microcomputer and PC were designed in detail in this paper. The testing soft of PC which was programmed with LabVIEW was divided into three modules which included database access module, serial communication module and data analysis module. to realize the acquistion、analysis、display of collected data. Data was storaged in the Access database of the office which was realized by using the LabSQL. In order to analysis data and curve fitting quickly, we used ActiveX technology, to call the MATLAB because of the powerful data processing function of MATLAB. The testing soft of the snigle-chip microcomputer which was divided into three parts that was AD converter module, PID regulator module and the crew of serial communications interface module mainly achieved parameters collection and upload,besided that ensured a constant flow in the acquisition process. This paper also introduced a method to diagnose critical cavitation points of centrifugal pump. Wavelet analysis was used to detect the mutation point of the import pressure pulse signals of centrifugal pump in order to determine the cavitation critical point in the paper. This method was more accurate compared with traditional methods.
【圖文】：

離心泵汽蝕性能自動(dòng)測(cè)試系統(tǒng)的研究所謂“中值濾波”就是對(duì)某一個(gè)測(cè)量連續(xù)采樣N次(一般N取奇數(shù))，然后把N個(gè)采樣值從小到大(或從大到小)排隊(duì)，再取中值作為本次采樣值。程序流程圖如圖2.1所示。 iii=i+lllsss(j)與s(i)互換換 iii===十 lll采采樣值=中問(wèn)值 值 iii=111 iii=i+lll圖2.1中值濾波程序流程圖中值濾波法的效果與N值有關(guān)。一般來(lái)說(shuō)，N的值不宜太大，，否則濾波效果反而不好。N值一般取3一5即可。中值濾波法對(duì)于去掉脈動(dòng)性質(zhì)的干擾比較有效。2.2.2.2算術(shù)平均值法算術(shù)平均法是尋找這樣一個(gè)歹作為本次采樣的平均值，使該值與本次各采樣值間誤差的平均和最小，即百=:客?)!.nin=…客住一川Inin(2一13)由一元函數(shù)求極值原理得(2一14)N藝間1一N式中:Y一一N次采樣值的算術(shù)平均值;xi—第i次采樣值;N—采樣次數(shù)。算術(shù)平均值適用與對(duì)壓力、流量一類信號(hào)的平滑處理。2.2.3去除采樣數(shù)據(jù)的趨勢(shì)項(xiàng)等待處理的數(shù)據(jù)中，一般都包含有兩種分量:一是周期大于數(shù)據(jù)采集周期的頻率成

示模塊作為存儲(chǔ)器或1/0設(shè)備直接掛在單片機(jī)的總線上。模塊的數(shù)據(jù)線接在單片機(jī)的數(shù)據(jù)總線上，片選及寄存器選擇信號(hào)由單片機(jī)的地址總線提供，讀和寫操作由單片機(jī)的讀寫信號(hào)控制。其具體的接口電路實(shí)現(xiàn)如圖3.4所示。
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2008
【分類號(hào)】：TH311

【引證文獻(xiàn)】

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