Search results for "computational fluid dynamics"
showing 10 items of 179 documents
Coupled hydraulic and electronic regulation of cross-flow turbines in hydraulic plants
2017
The potential benefit of coupling hydraulic and electronic regulation to maximize the energy production of a cross-flow turbine in hydraulic plants is analyzed and computed with reference to a specific case. Design criteria of the cross-flow turbine inside hydraulic plants are first summarized, along with the use of hydraulic regulation in the case of constant water head and variable discharge. Optimal turbine impeller rotational speed is derived, and traditional as well as innovative systems for electrical regulation are presented. A case study is analyzed to evaluate the potential energy production according to the expected monthly mean flow distribution and two possible choices: CFT1 wit…
Experimental characterisation of the CIRA plasma wind tunnel SCIROCCO test section
2008
Abstract During the Validation Phase of the CIRA-PWT SCIROCCO Facility located at Capua (Italy), a test campaign has been carried out to verify the performances of the facility with the use of the two conical nozzle configurations “D” and “F” with exit diameters are, respectively of, 1150 and 1950 mm. For the first time the data results of the tests have been used to characterize the plasma flow in the test section of the facility. In particular, analytical relationships between the main thermo-fluid-dynamic parameters in the test section and the reservoir conditions of the facility have been found, and compared to the CFD prediction developed during the Design Phase of the facility. Very i…
A preliminary method for the numerical prediction of the behavior of air bubbles in the design of Air Cavity Ships
2016
Air-cavity ships (ACS) are advanced marine vehicles that use air injection under hull to improve the vessel’s hydrodynamic characteristics. Although the concept of drag reduction by supplying gas under the ship’s bottom was proposed in the 19th century by Froude and Laval, at this time there are not many systematic studies on this subject. This paper is a preliminary work with the purpose of being a basic tool for the design of the ACS with computational fluid dynamic methods. The study aims to conduct a series of computational tests to compare the numerical models of bubble with experimental data. The first step of this study was to investigate the behavior of free bubble in water, conside…
Transient Modelling of Thermal Conditions in Test Buildings Including Radiation
2015
Abstract To increase the energy efficiency of buildings in Latvia's climate a comparative study with five experimental test buildings have been set up in Riga, Latvia. Different thermo physical quantities such as temperature, humidity, air velocity, etc. were monitored to better understand different behaviour of the building envelope. This gives an excellent validation possibility for the CFD model that in future could predict conditions in buildings with different envelopes. Previously a stationary model and transient model were considered without taking into consideration the thermal radiation. This study continues the previous work that was done and proposes a transient model which takes…
Slotted Blades Savonius Wind Turbine Analysis by CFD
2013
In this paper a new bucket configuration for a Savonius wind generator is proposed. Numerical analyses are performed to estimate the performances of the proposed configuration by means of the commercial code COMSOL Multiphysics® with respect to Savonius wind turbine with overlap only. Parametric analyses are performed, for a fixed overlap ratio, by varying the slot position; the results show that for slot positioned near the blade root, the Savonius rotor improves performances at low tip speed ratio, evidencing a better starting torque. This circumstance is confirmed by static analyses performed on the slotted blades in order to investigate the starting characteristic of the proposed Savoni…
Coupled Hydraulic and Electronic Regulation for Banki Turbines
2016
Abstract The potential benefit of coupling hydraulic and electronic regulation to maximize the energy production of a Bank turbine in hydraulic plants is analyzed and computed with reference to a specific case. Design criteria of the Banki turbine inside hydraulic plants are first summarized, along with the use of hydraulic regulation in the case of constant water head and variable discharge at the end of aqueducts feeding water distribution systems. Optimal turbine impeller rotational speed is derived and traditional, as well as innovative systems for electricity production according to controlled rotational speed of the generator are presented. The study case at the purification plant nam…
Data gathering and mathematical modelling for pitch stabilisation of a high speed catamaran
2011
This paper deals with the data gathering phase for a 21-foot long planing catamaran. The boat experiences a take-off phenomenon at high speed which needs to be countered. An overview of stability problems in high speed hydroplanes is described with possible solutions recommended. A subsequent gathering of data using laser scanning and computational fluid dynamics (CFD) analysis of the boat are described. The paper ends with a look at the initial developments of stabilising systems for the boat.
CFD simulations of dense sloid-liquid suspensions in baffled stirred tanks: Prediction of suspension curves
2011
Mixing of solid particles into liquids within contactors mechanically agitated by stirrers is a topic of primary importance for several industrial applications. A great research effort has been devoted to the assessment of the minimum impeller speed (Njs) able to guarantee the suspension of all particles. Conversely, only little attention has been paid so far to the evaluation of the amount of solid particles that are suspended at impeller speeds lower than Njs. In some cases the loss in available interfacial area between particles and liquid could be reasonably counterbalanced by a decreased mechanical power, making it of interest to evaluate the percentage of suspended solids at different…
CFD simulation of channels for direct and reverse electrodialysis
2012
Flows within very thin channels, typically filled with spacers, can be often encountered in many processes such as electrodialysis (ED) and reverse electrodialysis (RED). Although the ED and the RED processes have been studied for a long time, the optimization of the fluid dynamics within the channels is still an open problem. In the present work, realized within the EU-FP7 funded REAPower project, computational fluid dynamics simulations were carried out in order to predict the fluid flow field inside a single ED/RED channel. Some different configurations were tested which includes: an empty channel, a channel provided with a spacer, and a channel filled with a purposely manufactured fiber…
A Numerical Approach to the Keel Design of a Sailing Yacht
2008
This paper describes an approach to the keel design of a sailing yacht. The related software, which is fully automatic, permits to obtain an optimal shape by modifying the surface used to define the keel planform. B-spline curves and surfaces have been used because of their ability in following complex shapes. The algorithm integrates ad hoc implemented original software with Computational Fluid Dynamics (CFD) commercial ones. The optimisation procedure makes use of Genetic Algorithms (GAs) and a gradient – based optimiser for the refinement of the solution. A careful CAD and CFD modelling leads to a stable and efficient generalised method, which has been applied to the design of the centre…