New development in measuring large gradient temperature field with optical interference

Abstract

In this paper, we report a new development in the study of large gradient natural convection temperature field around a horizontally positioned cylinder by means of optical interference. The errors in measuring the temperature field caused by the light deflection and the method to reduce the errors are discussed. A series of interference patterns corresponding to the cylinder diameter of 33-86 millimeters and the wall temperature of 200-1180 C are presented. All these interference patterns are analyzed by the image processing. Results show that it is possible to obtain a high precision profile of the large gradient temperature field around the cylinder by means of optical interference. The boundary layer is as thick as several tens millimeters above the cylinder and 3-6 millimeters under and beside the cylinder. The results also show that the maximum value of the refractive index gradient does not occur at the surface of the cylinder.