Igor Iliev
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View article: Correlating Sediment Erosion in Rotary–Stationary Gaps of Francis Turbines with Complex Flow Patterns
Correlating Sediment Erosion in Rotary–Stationary Gaps of Francis Turbines with Complex Flow Patterns Open
Secondary flows in Francis turbines are induced by the presence of a gap between guide vanes and top–bottom covers and rotating–stationary geometries. The secondary flow developed in the clearance gap of guide vanes induces a leakage vorte…
View article: Including Lifetime Hydraulic Turbine Cost into Short-Term Hybrid Scheduling of Hydro and Solar
Including Lifetime Hydraulic Turbine Cost into Short-Term Hybrid Scheduling of Hydro and Solar Open
In traditional short-term hydropower scheduling problems, which usually determine the optimal power generation schedules within one week, the off-design zone of a hydraulic turbine is modeled as a forbidden zone due to the significantly in…
View article: Calibration of strain gauges on a model runner blade combining numerical and experimental data
Calibration of strain gauges on a model runner blade combining numerical and experimental data Open
In this paper, we present the calibration setup, method, and results for a set of strain gauges installed on the trailing edge of the runner blades of a model Francis turbine. The calibration work is done as a step in the HydroFlex project…
View article: Challenges with onboard strain measurements on a model Francis turbine runner
Challenges with onboard strain measurements on a model Francis turbine runner Open
As the world transitions towards more renewable energy sources, as a step to reduce the emissions of CO 2 , intermittent and non-dispatchable sources like solar and wind will take up a larger proportion of the energy production. With more …
View article: An experimental and numerical study of a three-lobe pump for pumped hydro storage applications
An experimental and numerical study of a three-lobe pump for pumped hydro storage applications Open
Pumped hydro storage (PHS) plays an important role as a matured technology that accounts for the vast majority of global energy storage capacity, and its expansion is therefore desirable. The expansion of PHS in mid- and high-water heads i…
View article: Multidisciplinary optimization of a Francis turbine runner
Multidisciplinary optimization of a Francis turbine runner Open
A fully automated multi-disciplinary design optimization procedure for a Francis turbine runner has been developed in a previous task of the Horizon2020-HydroFlex project. The design optimization was limited to blade design, with the goal …
View article: Decomposition of the structural response of the Francis-99 runner during resonance.
Decomposition of the structural response of the Francis-99 runner during resonance. Open
In this work, the complex structural response of the Francis-99 turbine runner is further investigated by decomposition of the output signal from previous Laser Doppler Vibrometry (LDV) measurements into the motion of each nodal diameter. …
View article: Sediment erosion in the labyrinths of Francis turbine: A numerical study
Sediment erosion in the labyrinths of Francis turbine: A numerical study Open
Development of new hydropower projects in Himalayan regions aims for the efficient performance of the turbine with lesser operation and maintenance cost. Over the past two decades, significant efforts have been made to improve the sediment…
View article: High flexibility in Francis turbine operation and design philosophy: A review
High flexibility in Francis turbine operation and design philosophy: A review Open
This paper examines and discusses how various operation schemes and design philosophies can prolong the expected lifetime of a hydro turbine subjected to many start-stop cycles and high ramping rates. With the proliferation of renewable an…
View article: Parameter based tool for Francis turbine guide vanes design using coupled MATLAB - ANSYS approach
Parameter based tool for Francis turbine guide vanes design using coupled MATLAB - ANSYS approach Open
The complex geometry of Francis turbine components can be defined parametrically so that automatic optimization techniques based on parametrization can be used. This is convenient for a hydraulic redesign of individual turbine elements. Co…
View article: Fully automated multidisciplinary design optimization of a variable speed turbine
Fully automated multidisciplinary design optimization of a variable speed turbine Open
The future electricity market will have large contributions from renewable energy sources such as solar and wind. The intermittent nature of these energy sources creates a need for highly flexible operation of hydropower stations and chang…
View article: Constraints of Parametrically Defined Guide Vanes for a High-Head Francis Turbine
Constraints of Parametrically Defined Guide Vanes for a High-Head Francis Turbine Open
This paper is focused on the guide vane cascade as one of the most crucial stationary sub-systems of the hydraulic turbine, which needs to provide efficient inflow hydraulic conditions to the runner. The guide vanes direct the flow from th…
View article: Optimization of Francis Turbines for Variable Speed Operation Using Surrogate Modeling Approach
Optimization of Francis Turbines for Variable Speed Operation Using Surrogate Modeling Approach Open
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 an existing turb…
View article: Numerical Study of a Francis Turbine over Wide Operating Range: Some Practical Aspects of Verification
Numerical Study of a Francis Turbine over Wide Operating Range: Some Practical Aspects of Verification Open
Hydropower plays an essential role in maintaining energy flexibility. Modern designs focus on sustainability and robustness using different numerical tools. Automatic optimization of the turbines is widely used, including low, mini and mic…
View article: Investigation of a Francis turbine during speed variation: Inception of cavitation
Investigation of a Francis turbine during speed variation: Inception of cavitation Open
Variable-speed operation of a hydro turbine is considered as an alternative option to meet fluctuating energy demand as it allows high-ramping rate. Cavitation can be a limiting factor to utilize the variable-speed technology at full poten…
View article: Francis turbines for variable speed operation
Francis turbines for variable speed operation Open
Ascribing to the recent trends of market-driven electricity production and increased deployment of non-dispatchable renewables globally, several researchers have suggested the use of variable speed technology to improve the operational fle…
View article: Influence of the guide vanes design on stress parameters of Francis-99 turbine
Influence of the guide vanes design on stress parameters of Francis-99 turbine Open
The frequencies with predominant amplitudes in low specific speed Francis turbines are related to rotor-stator interaction and they are calculated on the basis of the runner rotational speed and the number of guide vanes and runner blades.…
View article: Numerical prediction of hill charts of Francis turbines
Numerical prediction of hill charts of Francis turbines Open
This present work compares numerically predicted hill chart to experimental measurements of a Francis turbine. The main objective is to create a model for recreating hill charts using computational fluid dynamics (CFD). Accurate prediction…
View article: Variable-speed operation and pressure pulsations in a Francis turbine and a pump-turbine
Variable-speed operation and pressure pulsations in a Francis turbine and a pump-turbine Open
The paper presents result from model measurements of the efficiency and pressure pulsation intensities for two low-specific-speed hydraulic turbines operated at variable speed, namely, one splitter-bladed Francis turbine marked with "F99" …
View article: On the Rotor Stator Interaction Effects of Low Specific Speed Francis Turbines
On the Rotor Stator Interaction Effects of Low Specific Speed Francis Turbines Open
The rotor stator interaction in a low specific speed Francis model turbine and a pump-turbine is analyzed utilizing pressure sensors in the vaneless space and in the guide vane cascade. The measurements are analyzed relative to the runner …
View article: Simplified hydrodynamic analysis on the general shape of the hill charts of Francis turbines using shroud-streamline modeling
Simplified hydrodynamic analysis on the general shape of the hill charts of Francis turbines using shroud-streamline modeling Open
The paper presents a simplified one-dimensional calculation of the efficiency hill-chart for Francis turbines, based on the velocity triangles at the inlet and outlet of the runner's blade. Calculation is done for one streamline, namely th…
View article: Pressure Pulsation in a High Head Francis Turbine Operating at Variable Speed
Pressure Pulsation in a High Head Francis Turbine Operating at Variable Speed Open
This paper presents the preliminary work of the master thesis of the author, written at the Norwegian University of Science and Technology. Today, many Francis turbines experience formations of cracks in the runner due to pressure pulsatio…
View article: DESIGN AND FEM STATIC ANALYSIS OF AN INSTRUMENT FOR SURFACE PLASTIC DEFORMATION OF NON-PLANAR FUNCTIONAL SURFACES OF MACHINE PARTS
DESIGN AND FEM STATIC ANALYSIS OF AN INSTRUMENT FOR SURFACE PLASTIC DEFORMATION OF NON-PLANAR FUNCTIONAL SURFACES OF MACHINE PARTS Open
The paper presents the design of a specialized instrument for formation different types of regular microshape roughness on functional surfaces of parts with non-planar macroshape by using the process, called “surface plastic deformation”. …