Browsing NTNU Open by Author "Trivedi, Chirag"
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A review on fluid structure interaction in hydraulic turbines: A focus on hydrodynamic damping
Trivedi, Chirag (Journal article; Peer reviewed, 2017)Hydraulic turbines include stationary and rotating components. The interaction of the components, mainly between the runner blades and distributor vanes, is critical when the frequency of the rotor-stator interaction (RSI) ... -
Blade passage modeling strategy for hydraulic turbine
Gong, Ruzhi; Trivedi, Chirag; Dahlhaug, Ole Gunnar; Nielsen, Torbjørn Kristian (Journal article; Peer reviewed, 2017)CFD has played a significant role to investigate the performance and improve the design of hydraulic turbines; however, the improvement of CFD method demands powerful computer resources including time, CPU, memory, and ... -
A comprehensive review of verification and validation techniques applied to hydraulic turbines
Trivedi, Chirag; Dahlhaug, Ole Gunnar (Peer reviewed; Journal article, 2019)The paper critically reviews the verification and validation (VV) techniques applied to investigate hydraulic turbines. Although there are well-established standards such as AIAA G-077-1998 and ERCOFTAC guide for turbulence ... -
Design of a Turbine That Utilizes the Energy in Spill Water of Large Ships
Meek, Christoffer (Master thesis, 2018)In this master thesis, a Straflo turbine prototype used for energy recovering in large ships was tested, evaluated, and redesigned. The main goals were first to evaluate the performance of the prototype based on efficiency ... -
Experimental and Numerical Studies of a High-Head Francis Turbine: A Review of the Francis-99 Test Case
Trivedi, Chirag; Cervantes, Michel; Dahlhaug, Ole Gunnar (Peer reviewed; Journal article, 2016)Hydraulic turbines are widely used to meet real-time electricity demands. Computational fluid dynamic (CFD) techniques have played an important role in the design and development of such turbines. The simulation of a ... -
Experimental study of a Francis turbine under variable-speed and discharge conditions
Trivedi, Chirag; Agnalt, Einar; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2018)This work investigates the unsteady pressure fluctuations in a hydraulic turbine that are observed during steep ramping. Although hydraulic turbines are expected to operate seamlessly during steep ramping, the resulting ... -
Fluid-structure interactions in Francis turbines: A perspective review
Trivedi, Chirag; Cervantes, Michel (Journal article; Peer reviewed, 2017)Competitive electricity prices and reduced profit margins have forced hydraulic turbines to operate under critical conditions. The demand for extended operating ranges and the high efficiency of the turbine runners have ... -
FSI investigation of a hydrofoil
Heggebø, Karoline Eiane (Master thesis, 2017)Due to the changes in electricity production where intermittent energy sources like wind and solar power increase their ratio, a stabilizing energy source is required, which hydropower plants provides. The stabilization ... -
Interaction between trailing edge wake and vortex rings in a Francis turbine at runaway condition: Compressible large eddy simulation
Trivedi, Chirag; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2018)The present study aims to investigate the unsteady flow phenomenon that produces high energy stochastic fluctuations in a highly skewed blade cascade. A complex structure such as a turbine is operated at runaway speed, ... -
Investigation and validation of a Francis turbine at runaway operating conditions
Trivedi, Chirag; Cervantes, Michel; Gandhi, BK (Journal article; Peer reviewed, 2016)Hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters. The generator reaches no-load instantly. Consequently, the turbine runner accelerates to high speed, ... -
Investigation of a Francis turbine during speed variation: Inception of cavitation
Trivedi, Chirag; Iliev, Igor; Dahlhaug, Ole Gunnar; Zoran, Markov; Engstrom, Fredrik; Lysaker, Henning (Peer reviewed; Journal article, 2020)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 ... -
Investigation of the Numerical Methodology of a Model Wind Turbine Simulation
Tabatabaei, Narges; Cervantes, Michel; Trivedi, Chirag (Journal article; Peer reviewed, 2018)The present work aims to investigate different methodologies for the numerical simulation of an upwind three-bladed wind turbine; which is supposed to be a base model to simulate icing in cold climate windmills. That is a ... -
Investigation of the Unsteady Pressure Pulsations in the Prototype Francis Turbines -Part 1: Steady State Operating Conditions
Trivedi, Chirag; Gogstad, Peter Joachim; Dahlhaug, Ole Gunnar (Journal article, 2018)Hydropower is one of the most reliable renewable sources of electricity generation. With high efficiency and good regulating capacity, hydropower has the ability to meet rapid changes in power demand. Large investments in ... -
Investigation of the unsteady pressure pulsations in the prototype Francis turbines during load variation and startup
Trivedi, Chirag; Gogstad, Peter Joachim; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2017)This work investigates the unsteady pressure fluctuations in two prototype Francis turbines during load variation and start-up. Although hydraulic turbines are expected to experience such events over their lifetime, the ... -
Investigations of Compressible Turbulent Flow in a High-Head Francis Turbine
Trivedi, Chirag (Journal article; Peer reviewed, 2017)Dynamic stability of the high-head Francis turbines is one of the challenging problems. Unsteady rotor–stator interaction (RSI) develops dynamic stresses and leads to crack in the blades. In a high-head turbine, vaneless ... -
Investigations of unsteady pressure loading in a Francis turbine during variable-speed operation
Trivedi, Chirag; Agnalt, Einar; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2017)Current study was aimed to investigate the unsteady pressure loading in a model Francis turbine under variable-speed configurations. Focus was to investigate the time-dependent characteristic frequencies and the pressure ... -
Numerical Investigation of Flow Field subject to Vibrating Structure
Leonhardsen, Sondre (Master thesis, 2017)Hydraulic turbines are more often than before running at off-design conditions. The flow conditions outside the best efficiency point may increase the mechanical load, and hence fatigue, on the turbine blades. The flow-induced ... -
Numerical Simulation and Validation of a High Head Model Francis Turbine at Part Load Operating Condition
Goyal, Rahul; Trivedi, Chirag; Gandhi, BK; Cervantes, Michel (Journal article, 2017)Hydraulic turbines are operated over an extended operating range to meet the real time electricity demand. Turbines operated at part load have flow parameters not matching the designed ones. This results in unstable flow ... -
Numerical study of a Francis turbine over wide operating range: Some practical aspects of verification
Trivedi, Chirag; Iliev, Igor; Dahlhaug, Ole Gunnar (Peer reviewed; Journal article, 2020)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 ... -
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 ...