Experimental And Analytical Investigations Of The Effect Of Wall Roughness And A Curved Elbow Inlet On Thermal Blooming In Axial Pipe Flow

Prakash A. Iyer; Peter I-Wu Shen

doi:10.1117/12.931751

15 September 1981 Experimental And Analytical Investigations Of The Effect Of Wall Roughness And A Curved Elbow Inlet On Thermal Blooming In Axial Pipe Flow

Prakash A. Iyer, Peter I-Wu Shen

Author Affiliations +

Proceedings Volume 0270, High Power Lasers and Applications; (1981) https://doi.org/10.1117/12.931751
Event: 1981 Los Angeles Technical Symposium, 1980, Los Angeles, United States

Abstract

An experimental and theoretical study of thermal blooming phenomena in a laser beam propagating in an axial turbulent pipe flow is presented. The experiments were conducted by using a 250 watt CW CO2 laser as the heat source and a mixture of CO2 and N2 as the absorbing medium. The optical path difference (OPD) caused by the heating of the gas by the beam were measured by holographic interferometry, using a krypton laser at 0.5309 μM. The pipe wall roughness was varied by inserting an inner lining made of porous material. Two different inlet conditions to the pipe were considered in the experiments, namely, a straight inlet and a curved elbow. The theory was developed by modifying an existing numerical code in order to include the volumetric heating due to absorption of the laser radiation by the flowing gas. The theoretical OPDs were calculated directly from the temperature profiles, and comparison with the experimental values for the case with a straight inlet showed good agreement. The effects of a curved elbow inlet and pipe wall roughness on OPD were determined by comparison of the results with those for a straight inlet and smooth wall respectively.

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Prakash A. Iyer and Peter I-Wu Shen "Experimental And Analytical Investigations Of The Effect Of Wall Roughness And A Curved Elbow Inlet On Thermal Blooming In Axial Pipe Flow", Proc. SPIE 0270, High Power Lasers and Applications, (15 September 1981); https://doi.org/10.1117/12.931751

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