Change search
Refine search result
1 - 4 of 4
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Amiri, Kaveh
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Mulu, Berhanu
    Cervantes, Michel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Raisee, Mehrdad
    School of Mechanical Engineering, University of Tehran, Mechanical Engineering Department, University of Tehran.
    Effects of load variation on a Kaplan turbine runner2016In: International Journal of Fluid Machinery and Systems, ISSN 1882-9554, E-ISSN 1882-9554, Vol. 9, no 2, p. 182-193Article in journal (Refereed)
    Abstract [en]

    Introduction of intermittent electricity production systems like wind and solar power to electricity market together with the deregulation of electricity markets resulted in numerous start/stops, load variations and off-design operation of water turbines. Hydraulic turbines suffer from the varying loads exerted on their stationary and rotating parts during load variations they are not designed for such operating conditions. Investigations on part load operation of single regulated turbines, i.e., Francis and propeller, proved the formation of a rotating vortex rope (RVR) in the draft tube. The RVR induces pressure pulsations in the axial and rotating direction called plunging and rotating modes, respectively. This results in oscillating forces with two different frequencies on the runner blades, bearings and other rotating parts of the turbine. This study investigates the effect of transient operations on the pressure fluctuations exerted on the runner and mechanism of the RVR formation/mitigation. Draft tube and runner blades of the Porjus U9 model, a Kaplan turbine, were equipped with pressure sensors for this purpose. The model was run in off-cam mode during different load variations. The results showed that the transients between the best efficiency point and the high load occurs in a smooth way. However, during transitions to the part load a RVR forms in the draft tube which induces high level of fluctuations with two frequencies on the runner; plunging and rotating mode. Formation of the RVR during the load rejections coincides with sudden pressure change on the runner while its mitigation occurs in a smooth way.

  • 2.
    Baidar, Binaya
    et al.
    Department of Mechanical Engineering, Kathmandu University.
    Chitrakar, Sailesh
    Department of Mechanical Engineering, Kathmandu University.
    Koirala, Ravi
    Department of Mechanical Engineering, Kathmandu University.
    Neopane, Hari Prasad
    Department of Mechanical Engineering, Kathmandu University.
    Selection of Optimal Number of Francis Runner Blades for a Sediment Laden Micro Hydropower Plant in Nepal2015In: International Journal of Fluid Machinery and Systems, ISSN 1882-9554, E-ISSN 1882-9554, Vol. 8, no 4, p. 294-303Article in journal (Refereed)
    Abstract [en]

    The present study is conducted to identify a better design and optimal number of Francis runner blades for sediment laden high head micro hydropower site, Tara Khola in the Baglung district of Nepal. The runner is designed with in-house code and Computational Fluid Dynamics (CFD) analysis is performed to evaluate the performance with three configurations; 11, 13 and 17 numbers of runner blades. The three sets of runners were also investigated for the sediment erosion tendency. The runner with 13 blades shows better performance at design as well as in variable discharge conditions. 96.2% efficiency is obtained from the runner with 13 blades at the design point, and the runners with 17 and 11 blades have 88.25% and 76.63% efficiencies respectively. Further, the runner with 13 blades has better manufacturability than the runner with 17 blades as it has long and highly curved blade with small gaps between the blades, but it comes with 65% more erosion tendency than in the runner with 17 blades.

  • 3.
    Chitrakar, Sailesh
    et al.
    Kathmandu University, Nepal.
    Cervantes, Michel
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Thapa, Biraj Singh
    Kathmandu University, Nepal.
    Fully coupled FSI analysis of Francis turbines exposed to sediment erosion2014In: International Journal of Fluid Machinery and Systems, ISSN 1882-9554, E-ISSN 1882-9554, Vol. 7, no 3, p. 101-109, article id 9Article in journal (Refereed)
    Abstract [en]

    Sediment erosion is one of the key challenges in hydraulic turbines from a design and maintenance perspective in Himalayas. The present study focuses on choosing the best design in terms of blade angle distribution of a Francis turbine runner which has least erosion effect without influencing the efficiency and the structural integrity. A fully coupled Fluid-Structure-Interaction (FSI) analysis was performed through a multi-field solver, which showed that the maximum stress induced in the optimized design for better sediment handling, is less than that induced in the reference design. Some numerical validation techniques have been shown for both CFD and FSI analysis

  • 4.
    Goyal, Rahul
    et al.
    Department of Mechanical and Industrial Engineering, Indian Institute of Technology.
    Cervantes, Michel J.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics. Water Power Laboratory, Department of Energy and Process Engineering, Norwegian University of Science and Technology.
    Gandhi, Bhupendra K.
    Department of Mechanical and Industrial Engineering, Indian Institute of Technology.
    Characteristics of Synchronous and Asynchronous modes of fluctuations in Francis turbine draft tube during load variation2017In: International Journal of Fluid Machinery and Systems, ISSN 1882-9554, E-ISSN 1882-9554, Vol. 10, no 2, p. 164-175Article in journal (Refereed)
    Abstract [en]

    Francis turbines are often operated over a wide load range due to high flexibility in electricity demand and penetration of other renewable energies. This has raised significant concerns about the existing designing criteria. Hydraulic turbines are not designed to withstand large dynamic pressure loadings on the stationary and rotating parts during such conditions. Previous investigations on transient operating conditions of turbine were mainly focused on the pressure fluctuations due to the rotor-stator interaction. This study characterizes the synchronous and asynchronous pressure and velocity fluctuations due to rotor-stator interaction and rotating vortex rope during load variation, i.e. best efficiency point to part load and vice versa. The measurements were performed on the Francis-99 test case. The repeatability of the measurements was estimated by providing similar movement to guide vanes twenty times for both load rejection and load acceptance operations. Synchronized two dimensional particle image velocimetry and pressure measurements were performed to investigate the dominant frequencies of fluctuations, vortex rope formation, and modes (rotating and plunging) of the rotating vortex rope. The time of appearance and disappearance of rotating and plunging modes of vortex rope was investigated simultaneously in the pressure and velocity data. The asynchronous mode was observed to dominate over the synchronous mode in both velocity and pressure measurements.

1 - 4 of 4
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf