Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/2677
標題: 渦輪機葉片間隙與動態之非接觸式量測研究
Study of the Tip Clearance and Dynamical Measurements for Turbomachinery Using Non-contact Probes
作者: 陳建宇
Chen, Jian Yu
關鍵字: non-contact measurement;非接觸式量測;light probes;blade tip clearance;blade dynamic mode;光纖位移感測器;葉片間隙;葉片動態
出版社: 機械工程學系
摘要: 
摘 要
本研究是利用光纖位移感測器建立一套非接觸式量測系統,檢測渦輪機葉片振動的特性,內容包括應用理論與量測方法的說明。本研究在分析過程中,利用線性振盪方程式,推導出解析關係式(analytical relationship),描述葉片動態位移橢圓短長軸比與相位差之關係,藉以判斷葉片共振級數。本數學式可取代Heath (2000)報告中的多項式曲線逼近結果,也清楚說明葉片共振振幅不影響雙參數法對共振級數的判斷。
在實驗量測部分,風扇轉速範圍800rpm~2500rpm,以Heath (2000)雙參數法的觀念為基礎,分析轉動葉片的動態特性,探討葉片的共振頻率與共振振幅,與其在共振發生的區域內,振幅與轉速之間的相互關係。在實驗機組的設計與架構上,利用編碼器輸出渦輪機每旋轉一圈的定位脈衝訊號 (once-per-revolution, OPR),觸發DSP晶片控制8255資料擷取卡獲得葉片位移時序列資料,再經計算得葉片的偏移量以進行分析,並可調變觸發訊號的角度,針對不同葉片量測,將每片葉片的振動模態個別分析。隨著渦輪機轉速的不同,同樣可由DSP晶片內部程式調變擷取時間來獲得數據。
量測時發現風扇轉速有漂移的現象,實際渦輪機在高速運轉下很可能會發生同樣的情形,故本研究利用數值模擬的方法對此部份進行模擬,了解轉速漂移影響雙參數法對共振級數判斷產生的誤差。
關鍵字:非接觸式量測、光纖位移感測器、葉片間隙、葉片動態。

Abstract
This study sets up a non-contact measurement system with light probes for revealing vibration characteristics of rotor blades by using blade tip clearance. The two-parameter method in conjunction with measurements on a small fan is studied. The study finds an analytical relationship for the two-parameter method based on the linear vibration equation. This analytical result describes the relation between axis ratio of the blade dynamic ellipse and phase difference of the probes.
The speed of fan is in the range from 800 to 2500 rpm for the measurements of the tip clearance for dynamic analysis of the blade vibrations. Experiments include the one-probe method and two-probe method. The one-probe method measures vibration of an arbitrary blade with one probe located at a fixed position on the casing. Its purpose is to identify the resonant frequency and resonant amplitude of blade vibration. The two-probe method employs two probes located with an appropriate spacing on the casing. Blade displacements measured by two probes under different rotor speed are found. The application of two-parameter method is discussed by comparing with the results of experiment and simulation.
Finally, the blade vibration involving rotor speed drifting is studied by simulation. In this simulation, the amplitude and the frequency of disturbance on rotor speed for blade vibration are discussed.
Key words: non-contact measurement, light probes, blade tip clearance, blade dynamic mode.
URI: http://hdl.handle.net/11455/2677
Appears in Collections:機械工程學系所

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