Publications associées à Turbomachine

The influence of splitter blades and meridional profiles on the performance of small-scale turbopumps for ORC applications; analysis, neural network modeling and optimization

Jürg Alexander Schiffmann, Sajjad Zakeralhoseini

This work presents the influence of splitters on the performance of small-scale turbopumps for organic Rankine cycle applications numerically. Different design parameters, such as impeller diameter at the outlet, number of blades, blade angle at the traili ...

2023

Design, computational and experimental investigation of a small-scale turbopump for organic Rankine cycle systems

Jürg Alexander Schiffmann, Sajjad Zakeralhoseini

The hydraulic design, computational analysis, and experimental investigations of a high-speed small-scale turbopump for mobile waste heat recovery applications based on organic Rankine cycle systems are presented in this paper. Such applications demand hig ...

Elsevier2023

Thermal management for gas lubricated, high-speed turbomachinery

Jürg Alexander Schiffmann, Luis Eric Olmedo Ocampo, Wei Liu, Wanhui Liu

High-speed turbomachinery is commonly designed to achieve high power densities. Limited space for active cooling results in a challenging thermal management. A thermal modeling approach leveraging modern declarative programming capabilities is presented, y ...

2023

Small-scale turbopumps for waste heat recovery applications based on an organic Rankine cycle: a study from pre-design to experimental validation

Sajjad Zakeralhoseini

The organic Rankine cycle (ORC) system is among the technologies applied to exploit waste heat in vehicles. Since common organic fluids have lower latent heat than water, higher mass flow rates are required to convert the same waste heat, considerably incr ...

EPFL2023

Advanced design methods and non-ideal gas lubrication applied to aerodynamic bearings

Eliott Philippe Guenat

Clean and energy-efficient turbomachinery are playing an increasingly important role in the decarbonization of heating systems, waste heat recovery and transportation, as the use of small-scale heat pumping and fuel cells spreads. Such machines typically e ...

EPFL2020

Transposition of the mechanical behavior from model to prototype of Francis turbines

François Avellan, Joao Gomes Pereira Junior, Eduard Egusquiza

Hydropower is nowadays essential for balancing the electrical grid providing flexibility and fast response. The role of hydraulic turbines has changed from working at their Best Efficiency Point (BEP) to work in the whole operating range when demanded. Fra ...

Pergamon-Elsevier Science Ltd2020

GPU-accelerated numerical analysis of jet interference in a six-jet Pelton turbine using Finite Volume Particle Method

François Avellan, Ebrahim Jahanbakhsh, Audrey Paulette Solange Maertens, Sebastián Camilo Leguizamón Sarmiento, Siamak Alimirzazadeh, Christian Vessaz, Takashi Kumashiro

The Pelton turbine is an impulse turbine typically installed for high head hydroelectric power plants. For a site with a rated head H and discharge Q, a higher specific speed turbine results in a more compact generating unit with reduced manufacturing cost ...

Pergamon-Elsevier Science Ltd2020

Flexible Support for Gas-Lubricated Bearing Bushings

Jürg Alexander Schiffmann

Herringbone-grooved journal bearings (HGJBs) for high-speed turbo-machinery are often supported on O-rings due to their favorable stiffness and damping characteristics for stability and alignment reasons. They yield limited lifetime at high temperatures, i ...

2020

Narrow Impingement Channels: Recent Advancements and Future Directions

Peter Ott, Alexandros Terzis, Michele Gaffuri

This paper summarizes the state-of-the-art related to the heat transfer characteristics of narrow impingement cooling channels, which can nowadays be integrated within the external wall of turbine airfoils. Particular emphasis is given to the experimental ...

European Turbomachinery Society2019

Mitigating tip vortex cavitation by a flexible trailing thread

Mohamed Farhat, Ali Amini

Tip Vortex Cavitation (TVC) is a major issue in design and operation of axial hydraulic machines. We investigate the capacity of a flexible trailing thread in alleviating TVC by analyzing the flow-induced motion. For this purpose, a nylon thread with three ...

AMER INST PHYSICS2019

Physical Mechanism of Interblade Vortex Development at Deep Part Load Operation of a Francis Turbine

François Avellan, Arthur Tristan Favrel, Keita Yamamoto

For seamless integration of growing electricity production from intermittent renewable energy sources, Francis turbines are under increasing demand to extend their operating range. This requires Francis turbines to operate under off-design conditions, wher ...

ASME2019

Impact of large tip clearance ratios on the performance of a centrifugal compressor

Jürg Alexander Schiffmann, Markus Diehl

Ultra-compact and fast spinning turbomachinery is a key technology to increase performance of domestic heating applications and to address decentralization of power and heat as a consequence of the rise of renewable energy sources. Recently, a heat pump us ...

2019

Numerical investigation of the jet velocity profile and its influence on the Pelton turbine performance

François Avellan, Ebrahim Jahanbakhsh, Audrey Paulette Solange Maertens, Sebastián Camilo Leguizamón Sarmiento, Siamak Alimirzazadeh, Takashi Kumashiro

Numerical investigation of the unsteady flow patterns around the bucket can be helpful to improve the Pelton turbine efficiency. In fact, by studying the loss mechanisms in the flow, one can optimize the bucket design. For this purpose, an accurate investi ...

IOP PUBLISHING LTD2019

Potential and Challenges of ORC driven Heat Pumps Based on Gas Bearing Supported Turbomachinery

Violette Mounier

Electrically Driven Heat Pumps (EDHPs) have been identified as a key technology to reduce the energy consumption in the domestic space heating sector. However, since EDHPs require electrical power, they face issues related to network overload at peak-time, ...

EPFL2018

Monitoring a Francis Turbine Operating Conditions

François Avellan, Loïc Andolfatto, Joao Gomes Pereira Junior

Francis turbines are designed for a specific set of operating conditions that is particular to each hydropower plant site. It allows this type of turbine to extract as much hydraulic power as possible, as long as they are operating in the right conditions. ...

2018

ORC Driven Heat Pump Running on Gas Bearings for Domestic Applications: Proof of Concept and Thermo-Economic Improvement Potential

Jürg Alexander Schiffmann, Violette Mounier

ORC driven Heat Pumps (HP-ORC) offer a promising technology of thermally driven heat pumps (TDHPs) for domestic applications. Recently, a 40 kW HP-ORC unit based on gas supported turbomachinery has been investigated in which the ORC radial turbine drives t ...

2017

Turbocompressors for Domestic Heat Pumps – A Critical Review

Jürg Alexander Schiffmann, Jean-Baptiste Carré

Small-scale, oil-free radial compressors on gas lubricated bearings represent a promising alternative to state-of-the-art compressor technology for driving domestic sized heat pumps. The inherent characteristics of turbocompressors manage to fit the heat p ...

2017

Potential of Small-Scale Turbomachinery for Waste Heat Recovery on Automotive Internal Combustion Engines

Jürg Alexander Schiffmann, Eliott Philippe Guenat, Violette Mounier, Kévin Rosset

This paper investigates the waste heat recovery potential of internal combustion engines, using organic Rankine cycles running on small-scale radial turbomachinery. ORC are promising candidates for low-grade thermal sources and the use of dynamic expanders ...

2015

Optimization of a Shared Tailrace Channel of Two Pumped-Storage Plants by Physical and Numerical Modeling

Giovanni De Cesare, Martin Peter Bieri, Stéphane Christian Olivier Terrier, Sylvain Candolfi

Pump and turbine operations lead to head losses in the tailrace channel. Pumping discharge may be limited due to potential air entrainment into the pump shaft when the downstream reservoir is at its lowest level and the head losses are too high. Regarding ...

2014

Dynamic Modeling and Simulation of Two-stage Compression Heat Pumps with Flash Economizer

Daniel Favrat, Jean-Baptiste Carré, Samuel Henchoz, Simon Gailledrat

Multistage heat pumps are one of the most efficient technologies for delivering heat at temperatures below 100°C, Thanks to their fairly high exergy efficiency. In the recent years the development of radial compressors mounted on gas bearings have unlock t ...

2013