Browsing NTNU Open by Author "Trivedi, Chirag"
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Investigation of suction capability of a centrifugal pump impeller
Fosse, Rita Ones (Master thesis, 2021)Sentrifugalpumper er en turbomaskin, hvor løpehjulet øker trykket i væsken. Den første kjente prototypen for en sentrifugalpumpe eksisterte allerede på 1400-tallet. Det har vært en konstant utvikling fra den første kjente ... -
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 Rake and Rib Structures in Sand Traps to Prevent Sediment Transport in Hydropower Plants
Ivarson, Mads Mehus; Trivedi, Chirag; Vereide, Kaspar (Journal article; Peer reviewed, 2021)In order to increase the lifespan of hydraulic turbines in hydropower plants, it is necessary to minimize damages caused by sediment erosion. One solution is to reduce the amount of sediments by improving the design of ... -
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 ... -
Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine
Acharya, Nirmal; Gautam, Saroj; Chitrakar, Sailesh; Trivedi, Chirag; Dahlhaug, Ole Gunnar (Peer reviewed; Journal article, 2021)A clearance gap (CG) between guide vanes (GVs) and facing plates exists at both ends of a Francis turbine and allows the opening angle to be adjusted for varying operating conditions. Leakage flow is induced through this ... -
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 ... -
Numerical study of flow calming structures in hydropower plants
Ivarson, Mads Mehus (Master thesis, 2021)For å forlenge livsløpet til hydrauliske turbiner er det nødvendig å minimere skader forårsaket av sedimentslitasje. En mulig løsning er å forbedre sandfanget for å redusere mengden sedimenter som når turbinene. I dette ... -
Numerical study of particle settlement in a sand trap with multiple flow calming structures
Stjern, Rebekka Jennings (Master thesis, 2023)Et tradisjonelt sandfang i et vannkraftverk reduserer strømningshastigheten slik at sedimenter som transporteres kan skilles ut fra vannet. For å minimere turbinerosjon forårsaket av partikler er det nødvendig å optimere ... -
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 ... -
Pressure Pulsations and Fatigue Loads in High Head Francis Turbines
Solemslie, Bjørn Winther; Trivedi, Chirag; Agnalt, Einar; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2019)The Norwegian power system today includes a relatively large percentage of Francis turbines with a head of above 300m, in the world. This leads to a need to maintain and develop the national competence regarding the ... -
Signature analysis of characteristic frequencies in a Francis turbine
Trivedi, Chirag; Agnalt, Einar; Dahlhaug, Ole Gunnar; Brandåstrø, Bård Aslak (Journal article; Peer reviewed, 2019)The present work investigates the unsteady pressure fluctuations in a model Francis turbine that are observed during steady state operation. Focus of the present study is to correlate pressure fluctuations between stationary ... -
Simplified hydrodynamic analysis on the general shape of the hill charts of Francis turbines using shroud-streamline modeling
Iliev, Igor; Trivedi, Chirag; Dahlhaug, Ole Gunnar (Journal article; Peer reviewed, 2018)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 ... -
Simulation of Rotor-Stator Interactions (RSI's) in a High Head Francis Turbine
Selvig Hallén, Madeleine Josephine (Master thesis, 2018)As energy demand is growing along with the quest for green energy the operating range for hydropower is being pushed into non-favourable conditions. The unsteady flow regimes at these conditions lead to transient phenomenons ... -
The state-of-art of design and research for Pelton turbine casing, weight estimation, counterpressure operation and scientific challenges
Quaranta, Emanuele; Trivedi, Chirag (Peer reviewed; Journal article, 2021)The Pelton turbine is the most widespread and efficient impulse hydropower turbine. The Pelton casing is a static, but key component: the internal hydrodynamic phenomena affect the performance of the hydropower plant, the ... -
Study of laminar and turbulent flow in a square cross-section prepared for PIV measurements
Johnsen, Magnus Dale (Master thesis, 2022)Vannkraft, i form av effektive turbiner med lang levetid, forventes ̊a spille en nøkkelrolle i den grønne omstillingen. En forst ̊aelse av grunnleggende fluid- mekanikk er avgjørende for dette. Utnyttelsen av eksperimentelle ...