Search results for "turbine"
showing 10 items of 198 documents
Modelling of thermal stresses in bearing steel structure generated by electrical current impulses
2018
This work is the study of one particular candidate for white etching crack (WEC) initiation mechanism in wind turbine gearbox bearings: discharge current impulses flowing through bearing steel with associated thermal stresses and material fatigue. Using data/results from previously published works, the authors develop a series of models that are utilized to simulate these processes under various conditions/local microstructure configurations, as well as to verify the results of the previous numerical studies. Presented models show that the resulting stresses are several orders of magnitude below the fatigue limit/yield strength for the parameters used herein. Results and analysis of models …
Particle flow modelling in slurry-fed stirred vessels
2004
In this paper experimental information on the retention time distribution (RTD) of solid particles in a high-aspect-ratio vessel, stirred by three equally spaced Rushton turbines, is presented. The relevant data were obtained by a special technique named twin system approach (TSA) that greatly simpli+es the handling of particle-laden streams and is therefore particularly suited for investigating particle RTD in 9ow systems. The technique fundamentals are +rst summarized, together with the data analysis procedure. This lastly requires a numerical deconvolution operation that is easily performed with the help of Z-transforms. Two di;erent approaches for excluding the spurious contributions of…
Performance improvement of a Savonius water rotor with novel blade shapes
2021
Abstract Savonius water rotor is a prominent drag based turbine able to extract energy available in flowing water with low velocity like river streams, tidal currents or other man made water canals. However, in view of its low performance, an enhanced design of the rotor blades is necessary to better its efficiency. Therefore, the present study aims to improve the efficiency of Savonius rotor by changing the blade design. Different blade shapes were investigated numerically using computational fluid dynamics (CFD). Using conventional design, the peak power coefficient was found to be 0.166 at tip-speed ratio of 0.78. However, the peak power coefficient reaches 0.184 using the optimal blade …
Experiments and predictions of the transition of the flow pattern with impeller clearance in stirred tanks
2001
In the present work, the double- to single-loop flow pattern transition in a stirred vessel equipped with a Rushton turbine is investigated by Laser Doppler anemometry (LDA). In particular, the clearance at which such transition occurs is assessed by comparing axial velocity profiles underneath the impeller. Computational fluid dynamics (CFD) simulations of the same system are carried out, by employing the 'inner-outer' fully predictive computation strategy. The comparison of predicted results with the experimental data collected shows that the transition is well reproduced by simulations. A good agreement on the mean velocities is also observed but for the impeller discharge stream angle t…
Modelling and simulation of gas-liquid hydrodynamics in mechnically stirred tanks
2007
Abstract Computational fuid dynamics (CFD) is an increasingly important tool for carrying out realistic simulations of process equipment. In the case of multiphase systems the development of CFD models is less advanced than for single-phase systems. In the present work CFD simulations of gas–liquid stirred tanks are reported. An Eulerian–Eulerian multi-fluid approach is used in conjunction with the simplest two-phase extension of the k–ɛ turbulence model. All bubbles are assumed to share the same size. The effect of inter-phase forces on simulation results is separately considered. As concerns drag, it is shown that the sole parameter needed to characterize the dispersed phase behaviour is …
Integrating stated preferences, landscape metrics and attitudes to assess visual impact of wind turbines
2021
International audience
Design of Reliable and Efficient Banki-Type Turbines
2020
A new shape for the external surface of the Crossflow turbine blades is proposed, which allows for the preservation of hydraulic efficiency in spite of a significant maximum blade thickness providing mechanic robustness and reliability. The final shape of the blades is assessed using an iterative solution for two uncoupled models: a 2D computational fluid dynamic (CFD) and a structural 3D finite element method (FEM) analysis of a single blade. Application of the proposed methodology to the design of a power recovery system (PRS) turbine, a new backpressure Crossflow-type inline turbine for pressure regulation, and energy production in a real Sicilian site follows.
Flexural Test on a Full-Scale 60-kW Wind Turbine-Tower Telescopic Steel Pipe
2019
A full-scale static test to failure was conducted on 6-m (236.22 in.)-long steel pipes constituting a segment of a telescopic wind tower with a 60-kW wind turbine. The diameter of the circular cross section of the steel pipes was 900 mm (35.43 in.), and the nominal thickness was 10 mm (0.39 in.). The steel grade was 355 MPa (51,488 psi). The tests were conducted in a force-controlled mode in a four-point bending test with a shear-to-span ratio of 2.05. The flexural limit states developed in the form of ovalization of the cross section and of local buckling. The buckling occurred in the plastic range because of the diameter-to-thickness ratio of the section. Although local buckling caused sl…
Further Results on Modeling, Analysis, and Control Synthesis for Offshore Wind Turbine Systems
2014
Renewable energy is a hot topic all over the world. Nowadays, there are several sustainable renewable power solutions out there; hydro, wind, solar, wave, and biomass to name a few. Most countries have a tendency to want to become greener. In the past, all new wind parks were installed onshore. During the last decade, more and more wind parks were installed offshore, in shallow water. This chapter investigates a comparative study on the modeling, analysis, and control synthesis for the offshore wind turbine systems. More specifically, an \( {\mathcal{H}}_{\infty } \) static output-feedback control design with constrained information is designed. Constrained information indicates that a rema…