本研究主要為非定常管流層紊流轉換，特別是流場中壁面所產生之初始不穩定擾動之發展，利用自製微機電熱膜感測器去量測不同角度壁面之流況，並搭配熱線測速儀一同量測當作比較的基準，經量測發現初始擾動成長為入口下游20D~25D靠近壁面之區域；並觀察於不同參數下，流場發生不穩定之時機與其持續時間之差別，並利用希爾伯特-黃轉換分析，獲得其瞬時擾動特徵頻率與其振幅，並以數據統計方式探討不同角度感測器所量測之不穩定擾動訊號其交互相關性分析，獲得不穩定擾動最大相關性之延遲時間，藉此了解初始不穩定擾動之二維性。

Experiments were made to study the process of laminar-turbulent transition in a pulsating pipe flow. Particular interest was placed upon the initial growth of velocity fluctuations in the flow field. Measurements were made with a spanwise array of Self-made MEMS thermal film sensors flushed with the wall surface, and hot-wire velocity signals measured in the flow field. In general, I was found that initially the disturbances grew in the developing region, about 20 to 25 diameters downstream of the inlet of the pipe. By examining the hot-wire and MEMS signals measured, it was clearly seen that initially the disturbances grew in a thin layer very near the wall. The raw signals obtained allowed us to observed the time duration of the disturbances under different flow condition. The characteristics instantaneous frequency and amplitude of the disturbances were further analyzed with the Hilbert-Huang Transformation (HHT). Meanwhile, signals of the MEMS sensors measured at different circumferential angles were examined by correlation analysis, from which further physical insights were gained with respect to the two-dimensionality of the unstable disturbances developed initially on the wall surface.

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