LDA Experimental Research of Turbulent Swirling Flow Behind the Axial Fans in Pipe, Jet and Diffuser

Čantrak, S.; Janković, Novica Z.; Ilić, Dejan

doi:10.1007/978-3-030-58362-0_12

Cited by 1 publication

(3 citation statements)

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“…Determined invariant maps revealed three-component isotropic turbulence in the vortex core region, especially in the pipe axis and its zone. This is not case for the unrestricted flows, as shown in Čantrak et al 9 On the basis of obtained invariant maps, Reynolds stresses (an)isotropy were found to manifest in a similar way even in different flow regions.…”

Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

“…6,7 But, paper 6 reports that turbulent anisotropy occurs intensively in the region where oscillating vortex core exists, which is the case when there is an axially unrestricted turbulent swirl flow, as in the study. 8,9 Paper 10 demonstrates the method of calculation of the invariant maps on the basis of the high-speed stereo particle image velocimetry (HSS PIV) results. Application of this approach is continued in a research of the wing tip vortex, 11,12 as well as in this paper.…”

Section: Introductionmentioning

confidence: 99%

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High speed stereoscopic PIV investigation of the statistical characteristics of the axially restricted turbulent swirl flow behind the axial fan in pipe

Čantrak

Janković

2022

Advances in Mechanical Engineering

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Investigation of the turbulent swirl flow in the piping system is one of the most complex investigations in the field of energetics and turbulence. Axial fans in a pipe, without guide vanes, are widely used in practice and the problem of their duty point and energy efficiency is still extensively discussed. Analysis of the interaction between axial fans energy and construction parameters is one of the main topics in defining the fans energy efficiency potential. On one side, there is a three-dimensional velocity field in the wall-bounded flow with regions of great turbulence intensity. On the other side, there is a complex blade geometry, which generates the turbulent swirl flow. This paper presents research on the turbulent swirl flow, Rankine type, in an axially restricted system, using high-speed stereo particle image velocimetry (HSS PIV). Axial fan impeller, with outer diameter 0.399 m and nine twisted blades is the flow generator. The Reynolds number Re = 176,529 is achieved in the pipe. Reynolds stresses, statistical moments of higher order, and invariant maps are calculated based on the three component velocity fields. Here, intensive changes of all statistical parameters occur in radial and axial direction. In the flow region, four flow regions can be identified. Interaction of all these four flow regions produces extremely complex turbulent swirl flow, which is generated behind the axial fans. Determined invariant maps reveal turbulence structure. It is shown that the state of turbulence on the pipe axis is three-component isotropic, which is contrary to the case of axially unrestricted turbulent swirl flows. In the rest of the space, in the region up to r/ R = 0.52, the states of turbulence occur in the area in between the boundaries which designate axis-symmetric turbulence (contraction) and axis-symmetric turbulence (expansion), in the vicinity of the state of three-component isotropic turbulence.

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Section: Discussionmentioning

confidence: 77%