氣體迷宮式軸封之參數修正

Parameter Modification for Gas Labyrinth Seals

汽渦輪發電機組常使用的氣體迷宮軸封主要目的就是降低外殼與轉軸間的洩漏，但卻會影響轉子振動之穩定性，所以軸封動態係數在汽渦輪發電機組之模擬分析中佔有重要的一環。本文以Fluent 分析結果作為基準，將Childs以整體流理論推導的氣體迷宮軸封動態係數方程式進行修正。利用最小平方法得到其經驗參數 （m, n） 為入出口壓差的函數，修正後的動態係數計算值更加接近Fluent 的分析結果。讓使用者能大量節省計算時間與快速應用。

Gas labyrinth seals, widely used in steam turbine-generator sets toreduce steam leakage between casings and rotors, significantly affect thevibration stability of rotor train systems. Therefore, the modeling of gaslabyrinth seals has been a major concern in the rotordynamic simulation ofsteam turbine-generator sets. In this paper, the empirical parameters, (m,n) in the Childs’ bulk flow equations for the dynamic coefficients of gaslabyrinth seals are modified to yield better results for wider applicationranges. These parameters (m, n) are obtained as functions of inlet/outletpressure differences of seals by using least square fitting to the computedresults from Fluent. This study helps the user using modified bulk flowequations save computational time and implement applications quickly.