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dc.contributor.supervisor Tachie, Mark (Mechanical Engineering) en_US
dc.contributor.author Aleyasin, Seyed Sobhan
dc.date.accessioned 2019-01-08T16:07:34Z
dc.date.available 2019-01-08T16:07:34Z
dc.date.issued 2018 en_US
dc.date.submitted 2019-01-07T16:36:49Z en
dc.identifier.citation Aleyasin, S. S., Tachie, M.F., and Koupriyanov M., 2017, “PIV measurements in the near and intermediate field regions of jets issuing from eight different nozzle geometries,” Journal of Flow, Turbulence and Combustion, 99 (2): 329-351. en_US
dc.identifier.citation Aleyasin, S. S., Tachie, M.F., and Koupriyanov M., 2017, “Statistical properties of round, square and elliptic jets at low and moderate Reynolds numbers,” Journal of Fluids Engineering: 139(10): 101206. en_US
dc.identifier.citation Aleyasin, S. S., Fathi, N., Tachie, M.F., Vorobieff, P., and Koupriyanov, M., 2018 “On the development of incompressible round and equilateral triangular jets due to Reynolds number variation,” Journal of Fluids Engineering: 140 (11): 111202. en_US
dc.identifier.citation Aleyasin, S.S., and Tachie, M.F., 2018, “Comparative evaluation of single/twin round and elliptic jets using particle image velocimetry,” ASME Fluids Engineering Division Summer Meeting (FEDSM), Montreal, Canada. en_US
dc.identifier.citation Aleyasin, S.S., and Tachie, M.F., 2017, “Nozzle spacing effects on statistical properties of twin elliptic jets,” The 11th Pacific Symposium on Flow Visualization and Image Processing, Kumamoto, Japan en_US
dc.identifier.citation Aleyasin, S. S., and Tachie, M.F., “Statistical properties and structural analysis of three-dimensional twin round jets due to variation in Reynolds number,” International Journal of Heat and Fluid Flow: in Press. en_US
dc.identifier.uri http://hdl.handle.net/1993/33647
dc.description.abstract An experimental study was designed to investigate the effects of Reynolds number and nozzle geometry on the development and the structures of free turbulent single and twin jets. The velocity measurements were performed using a particle image velocimetry (PIV). Measurements were conducted in the symmetry planes of single round, elliptic, rectangular, triangular, cross, daisy, star and square jets, and the Reynolds number studied ranged from 2500 to 20000. The effects of the initial conditions on the jets’ properties are studied using the mean velocities, Reynolds stresses and triple velocity correlations. Also, several methods are employed to extract and examine the turbulent structures of the jets which are responsible for their different mixing performance. The results show that noncircular jets have shorter potential core length, faster growth of centerline turbulence intensity and higher velocity decay and spread rates. Due to the specific topology of the daisy and triangular jets, the normalized profiles of mean velocity and higher order turbulent statistics in their minor and major planes are close to each other, therefore, the turbulent kinetic energy can be approximated by k=0.5((u^2 )+2(v^2 )). In addition, proper orthogonal decomposition (POD) analysis shows that the fractional and cumulative energy of turbulent structures in both minor and major planes of the triangular jet are almost identical. In the elliptic and rectangular jets, the statistical quantities in the minor and major planes differ significantly. The swirling strength analysis shows that the vortical structures in the minor plane of the elliptic and rectangular jets are more intense compared to those in their major plane as well as in the round and square jets leading to a higher jet spreading in the minor planes. It is observed that an increase in Reynolds number decreases the decay and spread rates, however, at Re > 10000 they become asymptotic. The joint probability density function (JPDF) and weighted joint probability density function (WJPDF) analysis demonstrate that the dominant events that contribute towards the Reynolds shear stress are different upstream of the axis-switching point in the minor and major planes of the elliptic jet. Consequently, a sign change occurs in the distribution of the Reynolds shear stress in the major plane but not in the minor plane. In twin jets, upstream of the merging point, the levels of turbulence intensities and Reynolds shear stress are higher in the inner shear layers, but the opposite trend is observed downstream of the merging point. The swirling strength analysis reveals that the vortical structures are more intense in the inner shear layers upstream of the merging point, their strengths are equal at the merging point and eventually more intense in the outer shear layers after the merging point. The analysis performed at the turbulent/non-turbulent interface of the jets reveals no Reynolds number effect on conditional streamwise velocity and spanwise vorticity distribution. However, the values of conditional transverse velocity are significantly larger at the lowest Reynolds number. The two-point correlation functions point out that the turbulent structures in the outer shear layers are larger compared to the inner shear layers. en_US
dc.subject Axis-switching en_US
dc.subject Eddy viscosity en_US
dc.subject Integral length scales en_US
dc.subject Joint probability density function (JPDF) en_US
dc.subject Large-scale turbulent structures en_US
dc.subject Nozzle geometry en_US
dc.subject Particle image velocimetry (PIV) en_US
dc.subject Proper orthogonal decomposition (POD) en_US
dc.subject Reynolds number en_US
dc.subject Sharp contraction nozzle en_US
dc.subject Swirling strength en_US
dc.subject Turbulent jet en_US
dc.subject Three-dimensional twin jet en_US
dc.subject Turbulent/non-turbulent interface en_US
dc.subject Weighted joint probability density function (WJPDF) en_US
dc.title On the effects of initial conditions on statistical properties of single and twin turbulent jets en_US
dc.degree.discipline Mechanical Engineering en_US
dc.contributor.examiningcommittee Birouk, Madjid (Mechanical Engineering) Alfaro, Marolo (Civil Engineering) Nobes, David (Mechanical Engineering, University of Alberta) en_US
dc.degree.level Doctor of Philosophy (Ph.D.) en_US
dc.description.note February 2019 en_US


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