doc. Ing. Pavel Rudolf, Ph.D.

E-mail:   rudolf@fme.vutbr.cz  WWW:   http://khzs.fme.vutbr.cz/~rudolf Dept.:   Energy Institute Victor Kaplan Dept. of Fluid Engineering Position:   Head of Department Room:   A1/0545 Dept.:   Energy Institute Victor Kaplan Dept. of Fluid Engineering Position:   Associate Professor Room:   A1/0545 Dept.:   Energy Institute Victor Kaplan Dept. of Fluid Engineering Position:   Research Worker Room:   A1/0545 Dept.:   Energy Institute NCC Energy - Special Fluid Machines Division Position:   Head of Subdivision Dept.:   NeTME Centre NCC MESTEC - Special Fluid Machines Division Position:   Head of Subdivision

Supervised courses:

• Computational Fluid Dynamics (MVP)
• Computational Fluid Dynamics (MVP-A)
• Computational Fluid Dynamics (MVP-A)
• Computational Modeling of the Turbulent Flow (9VMT)
• Diploma Seminar (N-ETI) (MD6)
• Introduction to Computational Fluid Dynamics (MMP)
• Seminar of Applied Fluid Mechanics and Fluid Machines (0MT)
• Year Project FLI (MRR)

Publications:

• RUDOLF, P.; ŠTEFAN, D.:
  Reduced order model of draft tube flow,
  IOP Conference Series-Earth and Environmental Science, pp.1-10, (2014), IOP Science
  conference paper
  akce: 27th IAHR Symposium on Hydraulic Machinery and Systems, Montreal, 22.09.2014-26.09.2014
• JANČULA, D.; MIKULA, P.; MARŠÁLEK, B.; RUDOLF, P.; POCHYLÝ, F.:
  Selective method for cyanobacterial bloom removal: hydraulic jet cavitation experience, Springer Science+Business Media Dordrecht
  journal article in Web of Science
• RUDOLF, P.; HUDEC, M.; GRÍGER, M.; ŠTEFAN, D.:
  Characterization of the cavitating flow in converging-diverging nozzle based on experimental investigations,
  EPJ Web of Conferences, pp.1-6, ISBN 978-80-260-5375-0, (2014), EDP Sciences
  conference paper
  akce: Experimental fluid mechanics 2013, Kutná Hora, 19.11.2013-22.11.2013
• RUDOLF, P.; ŠTEFAN, D.:
  Decomposition of the swirling flow field downstream of Francis turbine runner,
  IOP Conference Series-Earth and Environmental Science, pp.1-8, (2012), IOP Publishing Ltd.
  conference paper
  akce: 26th IAHR Symposium on Hydraulic Machinery and Systems, Beijing, 19.08.2012-23.08.2012
• ŠTEFAN, D.; RUDOLF, P.; SKOTÁK, A.; MOTYČÁK, L.:
  Energy transformation and flow topology in an elbow draft tube,
  Applied andComputational Mechanics, Vol.6, (2012), No.1, pp.93-106, ISSN 1802-680X, University of West Bohemia
  journal article - other
• RUDOLF, P.; HUDEC, M.; ZUBÍK, P.; ŠTEFAN, D.:
  Experimental measurement and numerical modeling of cavitating flow in converging-diverging nozzle,
  EPJ Web of Conferences, pp.1-8, ISBN 978-80-7372-784-0, (2012), EDP Sciences
  conference paper
  akce: Experimental Fluid Mechanics 2011, Jičín, 22.11.2011-25.11.2011

List of publications at Portal BUT

Abstracts of most important papers:

• RUDOLF, P.; ŠTEFAN, D.:
  Reduced order model of draft tube flow,
  IOP Conference Series-Earth and Environmental Science, pp.1-10, (2014), IOP Science
  conference paper
  akce: 27th IAHR Symposium on Hydraulic Machinery and Systems, Montreal, 22.09.2014-26.09.2014
  Swirling flow with compact coherent structures is very good candidate for proper orthogonal decomposition (POD), i.e. for decomposition into eigenmodes, which are the cornerstones of the flow field. Present paper focuses on POD of steady flows, which correspond to different operating points of Francis turbine draft tube flow. Set of eigenmodes is built using a limited number of snapshots from computational simulations. Resulting reduced order model (ROM) describes whole operating range of the draft tube. ROM enables to interpolate in between the operating points exploiting the knowledge about significance of particular eigenmodes and thus reconstruct the velocity field in any operating point within the given range. Practical example, which employs axisymmetric simulations of the draft tube flow, illustrates accuracy of ROM in regions without vortex breakdown together with need for higher resolution of the snapshot database close to location of sudden flow changes (e.g. vortex breakdown). ROM based on POD interpolation is very suitable tool for insight into flow physics of the draft tube flows (especially energy transfers in between different operating points), for supply of data for subsequent stability analysis or as an initialization database for advanced flow simulations.
• JANČULA, D.; MIKULA, P.; MARŠÁLEK, B.; RUDOLF, P.; POCHYLÝ, F.:
  Selective method for cyanobacterial bloom removal: hydraulic jet cavitation experience, Springer Science+Business Media Dordrecht
  journal article in Web of Science
  The aim of this study was to investigate the suitability of hydraulic jet cavitation as a method for cyanobacterial water-bloom management. Effects of cavitation were studied on laboratory culture of the cyanobacterium Microcystis aeruginosa, on a culture of a green alga Chlorella kessleri (as a non-target species) as well as on a real cyanobacterial biomass with Microcystis sp. as a dominant species. Our results suggested that the cavitation treatment of cyanobacteria is capable of causing the disintegration of their gas vesicles. Using this treatment, up to 99 % removal efficiency of cyanobacteria was achieved. Moreover, no effect on cyanobacterial membrane integrity or metabolic activity was detected by flow cytometry; thus, hydraulic cavitation seems to be harmless from the viewpoint of possible release of cyanotoxins into the water column. The green algae (here C. kessleri) were not affected negatively by the cavitation, and thus, they may still act as the natural nutrient competitors of cyanobacteria in lakes, ponds or reservoirs treated by cavitation.
• RUDOLF, P.; HUDEC, M.; GRÍGER, M.; ŠTEFAN, D.:
  Characterization of the cavitating flow in converging-diverging nozzle based on experimental investigations,
  EPJ Web of Conferences, pp.1-6, ISBN 978-80-260-5375-0, (2014), EDP Sciences
  conference paper
  akce: Experimental fluid mechanics 2013, Kutná Hora, 19.11.2013-22.11.2013
  Cavitation phenomena occuring in converging-diverging nozzle (Venturi tube) are described in the paper. A closed test circuit with possibility to control both flow rate and static pressure level were used. Loss coefficient was evaluated for different sigma numbers resulting in full „static“ characterization of the nozzle. Visualizations of the cavitation pattern development were acquired and matched with evolution of the loss coefficient. Three cavitation regimes are described: partial cavitation, fully developed cavitation, supercavitation.
• RUDOLF, P.; ŠTEFAN, D.:
  Decomposition of the swirling flow field downstream of Francis turbine runner,
  IOP Conference Series-Earth and Environmental Science, pp.1-8, (2012), IOP Publishing Ltd.
  conference paper
  akce: 26th IAHR Symposium on Hydraulic Machinery and Systems, Beijing, 19.08.2012-23.08.2012
  Practical application of proper orthogonal decomposition (POD) is presented. Spatio-temporal behaviour of the coherent vortical structures in the draft tube of hydraulic turbine is studied for two partial load operating points. POD enables to identify the eigen modes, which compose the flow field and rank the modes according to their energy. Swirling flow fields are decomposed, which provides information about their streamwise and crosswise development and the energy transfer among modes. Presented methodology also assigns frequencies to the particular modes, which helps to identify the spectral properties of the flow with concrete mode shapes. Thus POD offers a complementary view to current time domain simulations or measurements.
• ŠTEFAN, D.; RUDOLF, P.; SKOTÁK, A.; MOTYČÁK, L.:
  Energy transformation and flow topology in an elbow draft tube,
  Applied andComputational Mechanics, Vol.6, (2012), No.1, pp.93-106, ISSN 1802-680X, University of West Bohemia
  journal article - other
  Paper presents a computational study of energy transformation in two geometrical configurations of Kaplan turbine elbow draft tube. Pressure recovery, hydraulic efficiency and loss coefficient are evaluated for a series of flow rates and swirl numbers corresponding to operating regimes of the turbine. These integral characteristics are then correlated with local flow field properties identified by extraction of topological features. Main focus is to find the reasons for hydraulic efficiency drop of the elbow draft tube.