Hydraulic cylinder | EPFL Graph Search

A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment (engineering vehicles), manufacturing machinery, elevators, and civil engineering. A hydraulic cylinder is a hydraulic actuator that provides linear motion when hydraulic energy is converted into mechanical movement. It can be likened to a muscle in that, when the hydraulic system of a machine is activated, the cylinder is responsible for providing the motion. Operation Hydraulic cylinders get their power from pressurized hydraulic fluid, which is incompressible. Typically oil is used as hydraulic fluid. The hydraulic cylinder consists of a cylinder barrel, in which a piston connected to a piston rod moves back and forth. The barrel is closed on one end by the cylinder bottom (also called the cap) and the other end by the cylinder head (also called the

Spatially varied flow impact on resistance in corrugated pipes

Fereshteh Bagherimiyab Hunkeler

The roughness coefficient is a significant factor in hydraulic design process, but carries vast uncertainty in practice. This paper reports the resistance coefficients of corrugated PVC pipes under different flow regimes (i.e. pressurised, gradually varied flow (GVF) and spatially varied flow (SVF) with increasing discharge). The investigated corrugated pipes are mainly used in subsurface drainage systems and carry a SVF. The influence of SVF on the roughness coefficient of such pipes has not yet been reported. The pipes were first examined to determine the roughness coefficient for pressurised flow. The influence of GVF and SVF was then studied. The results show that pipes behave differently in different flow regimes and the impacts of each flow condition on the flow resistance are reported here.

2011

CFD simulations of a Y-junction for the implementation of hydraulic short-circuit operating mode

François Avellan, Daniel Biner, Cécile Münch-Alligné

In the framework of the XFLEX HYDRO H2020 European Project, one of the demonstrators focuses on the implementation of the hydraulic short-circuit on the pump storage power plant of Grand-Maison owned by Electricite De France (EDF). The Grand-Maison power plant is a two-level plant production with one plant located above the downstream reservoir and equipped with four Pelton turbines; a second plant located downstream the reservoir and equipped with eight reversible pump-turbines. Hydraulic short circuit consists in running pumps and turbines in the meantime to balance the energy consumption of the pumps compared to the grid. Such an operating mode allows increasing the flexibility of the power plant and targeting the requirement of balancing the intermittent production due to the growing of new renewable energies such as wind and solar power plants. The hydraulic short-circuit operating mode leads to a change in the flow paths in the penstocks and junctions compared to the normal turbine or pump modes. Indeed, compared to the pump mode, this mode will lead to a flow derivation at the junction between the penstocks directed to the Pelton units and the penstocks directed to the upper reservoir. As this mode have not been scheduled at the beginning of the power plant construction, it is necessary to quantitatively assess the singular head losses generated at the junction to be able to simulate the complete behaviour of the power plant by means of a 1D model. CFD simulations are carried out with the Fluent software for several configurations of hydraulic short-circuit defined by the ratio of flow rate deviated to the Pelton turbines.

IOP PUBLISHING LTD2021

DuoTurbo: Implementation of a Counter-Rotating Hydroturbine for Energy Recovery in Drinking Water Networks

François Avellan, Daniel Biner, Samuel Chevailler, Vlad Hasmatuchi, Cécile Münch-Alligné

To enhance the sustainability of water supply systems, the development of new technologies for micro scale hydropower remains an active field of research. The present paper deals with the implementation of a new micro-hydroelectric system for drinking water facilities, targeting a gross capacity between 5 kW and 25 kW. A counter-rotating microturbine forms the core element of the energy recovery system. The modular in-line technology is supposed to require low capital expenditure, targeting profitability within 10 years. One stage of the DuoTurbo microturbine is composed of two axial counter-rotating runners, each one featured with a wet permanent magnet rim generator with independent speed regulation. This compact mechanical design facilitates the integration into existing drinking water installations. A first DuoTurbo product prototype is developed by means of a Computational Fluid Dynamics based hydraulic design along with laboratory tests to assess system efficiency and characteristics. The agreements between simulated and measured hydraulic characteristics with absolute errors widely below 5% validate the design approach to a large extent. The developed product prototype provides a maximum electrical power of 6.5 kW at a maximum hydraulic head of 75 m, reaching a hydroelectric peak efficiency of 59%. In 2019, a DuoTurbo pilot was commissioned at a drinking water facility to assess its long-term behavior and thus, to validate advanced technology readiness levels. To the best of the authors knowledge, it is the first implementation of a counter-rotating microturbine with independent runner speed regulation and wet rim generators in a real-world drinking water facility. A complete year of operation is monitored without showing significant drifts of efficiency and vibration. The demonstration of the system in operational environment at pre-commercial state is validated that can be attributed to a technology readiness level of 7. The overall results of this study are promising regarding further industrialization steps and potential broad-scale applicability of the DuoTurbo microturbine in the drinking water industry.

2021

DuoTurbo: Implementation of a Counter-Rotating Hydroturbine for Energy Recovery in Drinking Water Networks

François Avellan, Daniel Biner, Samuel Chevailler, Vlad Hasmatuchi, Cécile Münch-Alligné

2021