Frédéric Hauville

A Simulation Model for the Evaluation of the Electrical Power Potential Harnessed by a Marine Current Turbine

This paper deals with the development of a Matlab-Simulink model of a marine current turbine system through the modeling of the resource and the rotor. The simulation model has two purposes: performances and dynamic loads evaluation in different operating conditions and control system development for turbine operation based on pitch and speed control. In this case, it is necessary to find a compromise between the simulation model accuracy and the control-loop computational speed. The blade element momentum (BEM) approach is then used for the turbine modeling. As the developed simulation model is intended to be used as a sizing and site evaluation tool for current turbine installations, it has been applied to evaluate the extractable power from the Raz de Sein (Brittany, France). Indeed, tidal current data from the Raz de Sein are used to run the simulation model over various flow regimes and yield the power capture with time.

CFD Simulation and Experimental Validation of a Vertical Axis Turbine: Toward Variable Pitch Cross-Flow Marine Turbine for Maximizing Hydropower Extraction—The SHIVA Project

The paper describes the numerical simulation of a cross-flow axis water turbine, widely known as Darrieus turbine or VAWT. The numerical solver is the RANSE solver CFX. The method of resolution aims at calculating the instantaneous forces on the blades of such a turbine, and the energy produced. Due to the specific blade kinematics that can result of pitch variable systems and the complex flow particularly in the centre part of the turbine, a meshing strategy based on the mixing of both sliding or/and deforming mesh were used. Due to the moderate Reynolds number involved in such systems, various fluid models were used including laminar flow, fully turbulent model as k–ω SST model and a laminar-turbulent transition model. A convergence study was carried out for time step, which yielded to courant number lower than 5 and angular step below 1 ° with about 600.000 cells with y+ = 1 . Fixed pitch devices were simulated for comparison with experiments data available in the literature to validate the numerical model. The normal and tangential forces were compared for various flow conditions. The number of blades ranged from 1 to 3 , the Tip Speed Ratio ranged from 1.5 to 7.5 , the Reynolds number was about 4 ×10 4 . It was observed that the agreement between the experiments and the numerical results is very good with the turbulent model in all cases excepted for one low TSR case for which the blade section incidence is maximum. Next step will consist in running simulations with variable pitch.© 2011 ASME

Modèle aéroélastique appliqué à la déformation d'un gréement

ABSTRACT This study adds to the development of a non linear aeroelastic model which is destined to predict the behaviour of a thin flexible surface in contact with a flow under the hypothesis of an inviscid fluid. This fluid structure interaction model integrates a structure calculation, based on a membrane model, with a fluid calculation, based on a singularity method associated with a vortex method. The results on a J80 rig are compared to the experiments in situ.

Speedometer fault detection and GNSS fusion using Kalman filters

Navigation systems used in racing boats require sensors to be more and more sophisticated in order to obtain accurate information in real time. To meet the need for accuracy of the surface speed measurement, the mechanical sensor paddle wheel has been replaced by the ultrasonic sensor. This ultrasonic sensor measures the water speed precisely and with very good linearity. Furthermore, by its principle of operation, it measures the water flow several centimetres from the sensor, which puts it outside the boundary layer, the region close to the hull where the flow is disturbed. However, this sensor has several drawbacks: it is quite sensitive and if the flow contains too many air bubbles, the sensor picks them up, which can happen quite frequently on boat with a planing hull. Another limitation of this sensor is its low frequency measurement rate. In this paper we explain the techniques used based on Kalman filters to address these shortcomings, firstly by identifying the inaccurate measurements caused by inadvertent dropouts, then by improving the useful sensor frequency with GNSS data fusion.

Methodology for optimal wind vane design

Measurements of wind direction are sought after by a multitude of professionals in many different domains. Whether to recalibrate meteorological models or simply for leisure activities, the demand for accurate and responsive wind measurements is widespread. This study was motivated by the need to improve the responsiveness of direction measurements on yachts. Here we argue that the ideal form factor of the wind sensor can be determined using digital tools, rather than empirically, with the aim of improving the mechanical response of the wind vane. Then we present the results obtained by applying a predictive filter method tailored to the specified form factor. We have developed and experimentally validate a mathematical model describing the dynamic behavior of a wind vane. This model is then used to determine the form factor of the vane that will give the best possible response to perturbations it will encounter. To do so we use operational research tools, specifying the mechanical characteristics of the vane and by providing the future use conditions of the sensor, in the form of a wind speed spectral density. The design built from this optimization methodology helps reduce the response time of the vane by 44% compared to to designs currently in use. We then work on digital signal processing by using a predictive filter which takes into account the dynamic characteristics of the vane previously determined by the mathematical model. This step vastly improves the quality and sensitivity of the signal, leading to another reduction in response time of 83%. This brings the total decrease in response time at 90%. There is therefore not only an improvement in the quality of wind direction measurements, but also with respect to the set of data that is derived from this information. In the context of single-handed racing boats, the performance of the automatic pilot directly benefits from this improvement in responsiveness.