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Proceedings Paper

Dynamic digital speckle interferometry applied to optical diagnosis of gas-liquid phase change
Author(s): Yaozu Song; Hongling Zhang; Wei Zhang; Tianfeng Jiao
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Paper Abstract

In this paper, a Dynamic Digital Speckle Interferometry (DDSI) applied to optical diagnosis of gas-liquid phase change is proposed. The basic principle and experimental system of the DDSI are presented. This technology of flow optical diagnosis has the following three main advantages. First, DDSI uses a CCD camera as record device of a specklegram and a microcomputer, which processes the specklegrams to obtain a speckle interferogram. Therefore, the DDSI does not need the photographic film and optical dark room that usually are needed for holographic interferometry and speckle photography. Second, in DDSI technique, the information of density field in flow is obtained by using a double exposure with and without flow variation respectively. As a result, it can automatically eliminate the effect of the density nonuniformity of the optical windows of test section on the density measurement (like holographic interferometry). Third, the DDSI can be used for dynamic visualization and real time measurement of continuous variation of density with time in flow (like M-Z interferometry). The gas-liquid phase change process of freon R13 is investigated experimentally. By means of the DDSI technique, both density distributions in gas phase and liquid phase of R13, which are located on two sides of gas-liquid interface respectively, can be measured when gas-liquid phase change occurs. It is also observed that the interface between gas-phase and liquid-phase has a thickness of the order of hundreds micrometers, when the temperature of R13 flow comes close to its critical temperature. The variation laws of the interface thickness with the temperature of R13 are discussed. The interface behaviors of movement, disappearance and renewal are presented. The investigations show that DDSI is very suitable for the optical diagnosis of gas-liquid phase change in mini or micro scale. It provides an effective method for experimental investigations on heat transfer and flow in mini or micro scale.

Paper Details

Date Published: 26 November 2001
PDF: 9 pages
Proc. SPIE 4448, Optical Diagnostics for Fluids, Solids, and Combustion, (26 November 2001); doi: 10.1117/12.449367
Show Author Affiliations
Yaozu Song, Tsinghua Univ. (China)
Hongling Zhang, Tsinghua Univ. (China)
Wei Zhang, Tsinghua Univ. (China)
Tianfeng Jiao, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 4448:
Optical Diagnostics for Fluids, Solids, and Combustion
Carolyn R. Mercer; Soyoung Stephen Cha; Gongxin Shen, Editor(s)

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