螺槳空化影像之處理分析與應用

Processing, Analysis, and Applications for Cavitation Images of Marine Propellers

數值模擬所需時間與費用相較實驗而言節省許多，故目前已被大量運用於螺槳流場及空化現象的分析與預測，然而其精準程度需要以實驗手段來評估及驗證。本文描述了一套相位鎖定影像拍攝系統，並在螺槳單獨實驗中拍攝空化影像；再根據不同類型空化現象的特性，發展出合適的影像處理及分析程序，嘗試將空化影像轉化為有物理意義的參數數據。這些空化參數數據，不但能提供給數值模擬結果做對比之用，也可與單獨實驗所測得的螺槳動力數據結合，以釐清空化對螺槳動力表現的影響。 Numerical simulations take much less time and cost than experiments do, resulting in their massive usage nowadays in analyzing and predicting flows and cavitations associated with marine propellers. However, the precision and accuracy of numerical simulations need to be evaluated and validated with experimental approaches. This paper reports a phase-locked imaging system, which is incorporated with open-water tests for marine propellers to acquire associated cavitation images. According to the characteristics of different types of cavitation, suitable image processing and analysis algorithms are developed, attempting to transform the cavitation images into parameter data with physical meanings. These parameter data of cavitations can be used for not only the numerical simulations to compare with, but also for the propeller designers to combine with the dynamical data of the propellers to elucidate the cavitation effects on their dynamical performances.