Experimental and numerical studies on mass transfer characteristics behind an orifice in a circular pipe for application to pipe-wall thinning

Influence of swirling flow on mass and momentum transfer downstream of a pipe with elbow and orifice

“…These results suggest that the mass transfer coefficient grows with the swirl intensity up to S = 0.6 and the growth of the mass transfer coefficient seems to be saturated in swirl intensity larger than S = 0.6. indicates that the cross-sectional mean velocity distributions are axisymmetric, which are featured by the maximum velocity at the pipe center and the recirculating flow near the pipe wall. It should be mentioned that the mean velocity distribution downstream of the orifice without swirl (S = 0) is in close agreement with that of the straight pipe flow downstream of an orifice [19]. This result suggests that the influence of the secondary flow downstream of the elbow is negligibly small in the cross-sectional mean velocity downstream of the orifice at S = 0.…”

“…4. The depth measurement allows the evaluation of the mass transfer coefficient K from the following equation [19];…”

“…The swirl intensity of the flow, defined by the ratio of the circumferential momentum to the axial one, is estimated as 0.26 at 3 diameters upstream of the orifice. Since then, several experimental studies on the mass and momentum transfer downstream of the orifice have been carried out to elucidate the mechanism of pipe-wall thinning in the pipeline [12][13][14][15][16][17][18][19][20][21][22].…”

On the non-destructive measurement of local mass transfer using X-ray computed tomography

“…Goldstein and Cho [7] used an automated surface measuring system, akin to a CMM, to measure the mass transfer on a flat surface using the naphthalene sublimation method. Yamagata et al [18] measured the mass transfer downstream of an orifice in a circular pipe by measuring the surface height of a layer of benzoic acid before and after the experiment on two sectioned halves of a test specimen using a CMM. Mazhar et al [19] and Le et al [20] measured the local mass transfer and roughness in single and back-to-back bends using gypsum test sections, where the test section was sectioned and the surface topography was obtained by laser scanning of the worn surface.…”

“…The local wall thinning rates in the dissolving wall method have been measured using ultrasonic transducers (UT) [5,17], Coordinate Measuring Machine (CMM) measurements [7,18], laser scans of the internal surface [19,20] and through X-rays of the test section [5]. Ultrasonic sensors are commonly used for local wall thickness measurements or flaw inspection [14][15][16], and has been used to measure the local mass transfer rates at selected locations in straight pipes and downstream of an orifice [5,17].…”