• An Experimental Investigation of the Hydroynamic Damping of Vibrating Hydrofoils 

      Bergan, Carl Werdelin; Tengs, Erik Os; Solemslie, Bjørn Winther; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2019)
      As Francis turbines are chasing a higher efficiency, while trying to accommodate a wider load region, turbine blade fatigue is becoming a more pronounced problem. Details of the Fluid-Structure Interaction (FSI) between ...
    • Damping Measurements on a Multi-Blade Cascade with Multiple Degrees of Freedom: A Francis-99 Test Case 

      Bergan, Carl Werdelin; Tengs, Erik Os; Solemslie, Bjørn Winther; Østby, Petter Thorvald Krogh; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2019)
      Due to thinner blades and higher demands for flexibility, the high-head Francis runners designed today face considerable challenges that severely affect the runners' expected lifetime. For many high-head Francis runners, ...
    • Francis-99: Coupled simulation of the resonance effects in runner channels 

      Tengs, Erik Os; Fevåg, Live Salvesen; Storli, Pål-Tore Selbo (Journal article; Peer reviewed, 2019)
      A resonance phenomenon is observed experimentally in the runner channels of the Francis-99 model turbine runner. An incompressible CFD simulation is unable to simulate this. Two different coupled physics schemes are therefore ...
    • Model Order Reduction Technique Applied on Harmonic Analysis of a Submerged Vibrating Blade 

      Tengs, Erik Os; Charrassier, Flora; Storli, Pål-Tore Selbo; Holst, Martin (Journal article; Peer reviewed, 2019)
      As part of an ongoing study into hydropower runner failure, a submerged, vibrating blade is investigated both experimentally and numerically. The numerical simulations performed are fully coupled acoustic-structural ...
    • Numerical Generation of Hill-Diagrams; Validation on the Francis99 Model Turbine 

      Tengs, Erik Os; Storli, Pål-Tore Selbo; Holst, Martin (Journal article; Peer reviewed, 2018)
      This article compares a numerically simulated, and an experimentally obtained Hill-Diagram. The Francis99 model turbine was used in the validation. By using steady-state simulations and passage modeling in ANSYS CFX, the ...
    • Numerical simulation of a droplet-film collision using a phase-field approach 

      Tengs, Erik Os (Master thesis, 2016)
      Computational Fluid Dynamics is the science of solving the governing equations of fluid motion numerically. Simulating multiphase flow has traditionally been difficult, due to non-uniform fluid properties and challenges ...
    • Numerical simulation of Fluid-Structure Interaction in high head Francis turbines 

      Tengs, Erik Os (Doctoral theses at NTNU;2019:229, Doctoral thesis, 2019)
      Renewable energy sources are becoming an integral part of the global energy mix. As hydropower can be used to stabilize the new energy market, this calls for increased demands from Francis turbines. Accurate calculation ...
    • Optimization of Francis Turbines for Variable Speed Operation Using Surrogate Modeling Approach 

      Iliev, Igor; Tengs, Erik Os; Trivedi, Chirag; Dahlhaug, Ole Gunnar (Peer reviewed; Journal article, 2020)
      Previous studies suggested variable speed operation (VSO) of Francis turbines as a measure to improve the efficiency at off-design operating conditions. This is, however, strongly dependent on the hydraulic design and, for ...
    • Optimization procedure for variable speed turbine design 

      Tengs, Erik Os; Storli, Pål-Tore Selbo; Holst, Martin (Journal article; Peer reviewed, 2018)
      This article outlines a design procedure for variable speed Francis turbines using optimization software. A fully parameterized turbine design procedure is implemented in MATLAB. ANSYS CFX is used to create hill diagrams ...
    • Two-way coupled simulation of the Francis-99 hydrofoil using model order reduction 

      Tengs, Erik Os; Einzinger, Johannes; Storli, Pål-Tore Selbo (Journal article; Peer reviewed, 2019)
      The Francis-99 hydrofoil is simulated using a quasi two-way Fluid-Structure Interaction procedure. The structural domain is reduced by the use of modal decomposition, and solved for inside the commercial fluid solver ANSYS ...