中文摘要：

气泡羽流是在曝气过程中产生的一种复杂的两相流动。对气泡羽流中气泡速度信息的提取是粒子图像测速算法(PIV)的核心部分。速度信息的提取即数字图像的预处理过程。本研究主要是在读取灰度值后,通过大津法得到相应的最佳阈值分割点,再采用该灰度阈值对图像进行二值化,以此来减少噪声对流场的影响,降低图像后处理的难度,这是气泡羽流的运动规律研究的一个重要过程。图像的二值化处理能有效地提高PIV技术计算流场的精度,为研究气泡羽流在曝气过程中产生的不稳定结构奠定了基础。

英文摘要：

Bubble plume is the two-phase complex flow produced during the aeration.Extracting the speed information of bubbles is the core of the particle image velocimetry(PIV) in the bubble plume.The extraction of speed information is the digital image preprocessing.The image binarization based on (Otsu's) method was employed to improve thresholding method after reading the gray value.It is an important process to the motion of bubble plume,effectively decreasing the effects of noise in the flow field and lowering t...