J. Phys. IV France 125 (2005) 339-341
DOI: 10.1051/jp4:2005125080

Determination of velocity profiles in pipes by a pulsed photoacoustic method

F. Hernández¹, J. Morales¹, M. Navarrete² and M. Villagrán-Muniz<sup>3

1</sup>  Posgrado de la Facultad de Ingeniería, UNAM, A.P. 70-258, CP 04511, Mexico, DF
²  Instituto de Ingeniería, Edificio 12, Sección de Ing. Mecánica Térmica y Fluidos, UNAM, A. P. 70-472, CP 04510, Mexico, DF
³  Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Laboratorio de Fotofísica, UNAM, A.P. 70-186, Mexico, DF

Abstract
The present work describes the development of a pulsed photoacoustic (PA) flowmeter. An acoustic wave in a flowing fluid is produced by absorption of a laser pulse focused over a path flow line. The acoustic propagations, along and against the flow, are monitored by two cw probe beams. In the interaction, the probe beam undergoes a transient deflection that is detected by a fast response photodiode (PD). Measurements of the acoustic arrival time through the pipe cross section are acquired. The velocity distribution data profile of a square pipe is obtained applying the cylindrical shockwave model developed by Vlasses and the velocity equation established in an earlier work by Zapka and Tam [9]. The profiles determined with this method are fixed through two turbulent pipe flow models, showing good agreement.

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