TVP螺槳空化實驗研究

EXPERIMENTAL STUDY ON CAVITATION ASSOCIATED WITH TVP

對於一新穎的螺槳設計－－跨速度域螺槳（Trans-Velocity Propeller, TVP），需要以實驗來測定其空化發生的形態與位置。本研究以現場可程式化閘陣列（Field-Programmable Gate Array, FPGA）建構即時控制系統，以相位鎖定（phase-locked）的方式來進行螺槳空化影像拍攝，所得到的空化影像再經由影像處理程序，包括直方圖等化、去除背景、二元化、膨脹侵蝕等算則，最後獲得螺槳葉片上的瞬時空化發生起始線。將所有影像上的瞬時空化發生起始線做空間平均，可得到TVP螺槳表面上之空化分佈的變動範圍和空化發生起始線的平均位置，確定空化與非空化位置。本研究之實驗數據可用於驗證空化數值模擬的結果，並可在日後進一步探討空化與紊流之間的關係。 For a novel propeller design - Trans-Velocity Propeller (TVP), the type and position of the cavitation occurring on the TVP needs to be determined experimentally. In this study, a Field-Programmable Gate Array (FPGA) was used to construct a real-time control system, which achieves phase-locked imaging for the cavitation. The cavitation images acquired were processed with a procedure of several algorithms including histogram equalization, background removal, thresholding, dilation and erosion, etc., to obtain for each image an instantaneous front line of cavitation on the propeller blade. Spatially averaging all the instantaneous front lines associated with the cavitation images, the variation range and averaged front line position of the cavitation distribution on the TVP can be obtained. These results can be used to study the cavitation phenomenon and design issues associated with the TVP.