飞机燃油管道中的润湿阻力及其光学测量

Wet resistance force in aircraft fuel pipe and its optical measurement

文中建立一种激光测量燃油管道润湿阻力的方法及实验装置。得到了小流管条件下润湿阻力大小的解析表达式,即液体表面斜率与反射亮场及入射光通光半径之间的解析关系。根据弯曲液体表面光反射原理及光电自动检测原理,建立了润湿阻力的激光测量实验装置。依据激光反射图样光斑大小可以测出液面的斜率和液面与管壁的接触角。再根据润湿阻力的解析式,得到了润湿阻力大小。实验上,观察到特殊的弯曲液体表面激光反射图样,该图样为圆形光斑,具有明显的干涉圆环。圆形光斑的大小不仅与入射光通光半径有关,而且与表面的弯曲度有关。理论上润湿阻力的大小与液体的表面张力成正比,与接触角的余弦值成正比。本装置具有无损和自动化特点。

A kind of method by means of laser was suggested and experimental set-up was constructed to study wet resistance in fuel pipe and its measurement. The wet resistance force would be acted on the fluid by the surface of the pip because of the wet effect between the liquid and the pip surface. The expression of wet resistance force was derived under small pip condition based on the liquid principle. A laser measurement set-up was constructed based on the light reflected from curved liquid surface and automatic electron-optics detection. The diameter of the special optics pattern depended on both the aperture diameter and curved degree of liquid surface. The analytic expression of light pattern diameter related with the slope of curved liquid surface and aperture diameter was arrived theoretically. The force depended linearly on the liquid surface tension and cosine of contact angle. A special pattern reflected from curved liquid surface was observed which was circle with clear interference fringes. The slop of liquid surface and contact angle was detected by means of the pattern scale and the experimental value of wet resistance force was archived. It has no-touch, no-damage and automatic properties.