研制了悬滴法液体表面张力测量系统，该系统包括图像采集系统、耐高压实验本体和温度控制系统等．悬滴图像信息由高分辨率的CM OS相机采集，并利用Canny算法进行边缘检测，进而提取悬滴边界并进行坐标变换，以获取悬滴的轮廓坐标，采用坐标轮换法与New ton法结合实现悬滴边界的全轮廓拟合计算．实验系统的温度范围和温度波动度分别为：20～180℃，±0．01℃；压力范围为：0～20 M Pa ．为了检验系统的可靠性和精确性，测量了正庚烷在温度范围为293．15～373．15 K的表面张力．通过不确定度分析，测量流体表／界面张力的相对不确定度为0．22％．%A pendent‐drop apparatus ,consisting of image acquisition ,pressure vessel ,tempera‐ture control and liquid drop gerneration systems was developed to accurately determine the liquid sur‐face tension .A CMOS digital camera was adopted to capture and process the image of the liquid drop . The edge of the image was then detected by Canny operator and fitted to the theoretical equation of liquid drop with Matlab to obtain the surface/interfical tension .The pressure vessel ,its temperature‐the was well controlled in the range from 20 ℃ to 180 ℃ with a stability better than 0 .01 ℃ ,could work under the pressure up to 20 MPa .The surface tension of heptane was measured in the tempera‐ture range from 293 .15 K to 373 .15 K and a good agreement was achieved with literature .The rela‐tive uncertainty was better than 0 .22%.
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