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Fractal Fract
Special Issues
Turbulence Structure and Fractal Characteristics in Turbomachinery
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Turbulence Structure and Fractal Characteristics in Turbomachinery

A special issue of Fractal and Fractional (ISSN 2504-3110). This special issue belongs to the section "Engineering".

Deadline for manuscript submissions: closed (15 April 2023) | Viewed by 2594

Special Issue Editors

Dr. Ran Tao

E-Mail Website
Guest Editor
College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China
Interests: energy loss mechanisms of pump–turbines; water jet propulsion; operation stability analysis of bulb turbines; tracking studies on spatial characteristics
Special Issues, Collections and Topics in MDPI journals
Dr. Di Zhu

E-Mail Website
Guest Editor
College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100107, China
Interests: optimization design of fluid machinery
Dr. Zhicong Wei

E-Mail Website
Guest Editor
School of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China
Interests: flow-induced noise mechanism and control
Dr. Faye Jin

E-Mail Website
Guest Editor
Department of Energy and Power Engineering, Tsinghua University, Beijing 100190, China
Interests: nonlinear dynamics analysis of turbomachinery

Special Issue Information

Dear Colleagues,

Turbomachinery is a type of power machinery that relies on continuous rotating blades to convert energy between fluid media and shaft power. The application field of turbomachinery covers many industrial categories, and basic research related to this field has also attracted people's attention. The flow in turbomachinery is often the focus of researchers. However, the law of fully developed turbulence is not yet clearly understood. This Special Issue focuses on the research of turbulent structures in turbomachinery, including basic research, experimental testing, computational fluid dynamics analysis, etc. The analysis of fractal and fractal-dimensional characteristics of turbulence structures will help us to understand the field more deeply. These studies are expected to contribute to the progress of engineering projects. The research objects of this Special Issue include pumps; fans; compressors; steam turbines; water turbines; wind turbines and other kinds of turbomachinery. Theoretical analyses, experimental research and numerical research are welcome.

Dr. Ran Tao
Dr. Di Zhu
Dr. Zhicong Wei
Dr. Faye Jin
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fractal and Fractional is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • secondary flow
  • rotating stall
  • jet-wake flow
  • vortex rope
  • vortex shedding
  • cavitation
  • turbomachinery
  • secondary flow
  • vortex identification
  • fractal dimension
  • entropy

Published Papers (2 papers)

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Research

12 pages, 3980 KiB  
Article
Investigation of Fractal Characteristics of Karman Vortex for NACA0009 Hydrofoil
by Fangfang Zhang, Yaju Zuo, Di Zhu, Ran Tao and Ruofu Xiao
Fractal Fract. 2023, 7(6), 467; https://doi.org/10.3390/fractalfract7060467 - 10 Jun 2023
Viewed by 952
Abstract
A Karman vortex is a phenomenon of fluid flow that can cause fluctuation and vibration. As a result, it leads to fatigue damage to structures and induces safety accidents. Therefore, the analysis of the shedding law and strength of the Karman vortex is [...] Read more.
A Karman vortex is a phenomenon of fluid flow that can cause fluctuation and vibration. As a result, it leads to fatigue damage to structures and induces safety accidents. Therefore, the analysis of the shedding law and strength of the Karman vortex is significant. To further understand the laws of turbulent Karman vortex shedding and strength, this study conducts a numerical vorticity simulation of a Karman vortex at the trailing edge of a hydrofoil based on the two-dimensional simplified model of the NACA0009 hydrofoil under different Reynolds numbers. Combined with image segmentation technology, the fractal characteristics of a turbulent Karman vortex at the trailing edge of a hydrofoil are extracted, the number and total area of vortex cores are calculated, and the fractal dimension of the vortex is obtained. The results show that the fractal dimension can characterize the change in vortex shape and strength under different Reynolds numbers, and that the fractal analysis method is feasible and effective for the shedding analysis of a turbulent Karman vortex. Full article
(This article belongs to the Special Issue Turbulence Structure and Fractal Characteristics in Turbomachinery)
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18 pages, 4980 KiB  
Article
Comparative Study on the Fractal and Fractal Dimension of the Vortex Structure of Hydrofoil’s Tip Leakage Flow
by Zilong Hu, Yanzhao Wu, Puxi Li, Ruofu Xiao and Ran Tao
Fractal Fract. 2023, 7(2), 123; https://doi.org/10.3390/fractalfract7020123 - 28 Jan 2023
Cited by 2 | Viewed by 1295
Abstract
Axial-flow turbomachinery is widely used in low head water transfer and electricity generation projects. As there is a gap between the impeller and casing of the tubular flow unit, the fluid will cross the gap to form tip leakage flow, which may induce [...] Read more.
Axial-flow turbomachinery is widely used in low head water transfer and electricity generation projects. As there is a gap between the impeller and casing of the tubular flow unit, the fluid will cross the gap to form tip leakage flow, which may induce intense pressure pulsation, noise and mechanical vibration, and even threaten the safe operation of the unit. In order to ensure the efficient and stable operation of hydropower units, the influence factors of tip clearance flow and its formation and development mechanism have been deeply studied in this paper. In this paper, the impact of gap width, angle of attack and inlet velocity on tip leakage flow of hydrofoil with clearance are studied by orthogonal experiment method. The results suggest that the gap width has the greatest influence on tip clearance flow, the incidence angle takes the second place, and the inlet velocity has the least effect on tip clearance flow. Then the fractal characteristics of tip leakage vortices with different gap widths are studied. The results demonstrate that the fractal dimension of tip leakage vortices in large gaps was significantly larger than that in small gaps; The fractal dimension of the leakage vortex decreases gradually along the flow direction. Full article
(This article belongs to the Special Issue Turbulence Structure and Fractal Characteristics in Turbomachinery)
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