应用于微尺度流动与传热研究的激光散斑云纹干涉技术

Optical flow visualization is one of very important methods for researches of micro scale flow and heat transfer. According to the relation between the micro scale direction of test section and the direction of measuring light beam, the micro scale effects can be divided into traverse effect and longitudinal effect. In this project, two optical flow visualization methods which can be applicable for different micro scale effects are proposed. The micro scale traverse effect means that the micro scale direction of test section occurs only in direction vertical to propagation direction of measuring light beam. The dynamic digital speckle interferometry applied to optical flow visualization for the micro scale traverse effect is presented. By means of this method, the vapor-liquid phase change process of Freon R13 near its critical temperature is investigated experimentally. The variation laws of micro scale phase interface between vapor and liquid are obtained. The micro scale longitudinal effect means the micro scale direction of test section occurs in propagation direction of measuring light beam. For this micro scale flow, a laser Moire deflectometry is introduced. By using this technique the micro scale temperature field of natural convection around a heated thin wire and measured. Experimental researches show that the spatial resolution of laser Moire deflectometry is about 4μm. Its measurement accuracy can be 1/25 distance between two moiré fringes and measurement sensitivity for the deflective angle of light beam is about 1/1000 degree. The investigations in this project provide an effective method for experimental researches of flow and heat transfer in mini/micro scale.

光学显示与测量是微尺度流动与传热研究中的重要实验手段。本项目提出的利用动态激光散斑云纹干涉技术可以实时动态显示与测量在非稳定的微尺度流动条件下的流体的密度场分布与温度场分布，空间分辨率达1微米。它不仅为微流体力学与微传热学的研究提供一种十分行У氖笛槭侄危曳⒄沽巳任锢砹抗庋Р馐约际酰哂忻飨缘难跻庖逵胗τ眉壑怠