scholarly journals CFD Validation of a Model Wind Turbine by Means of Improved and Delayed Detached Eddy Simulation in OpenFOAM

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1306
Author(s):  
Camilo Sedano ◽  
Frederik Berger ◽  
Hamid Rahimi ◽  
Omar Lopez Mejia ◽  
Martin Kühn ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Computational Models ◽  
Turbine Blades ◽  
Bending Moment ◽  
Computational Time ◽  
Experimental Investigations ◽  
Detached Eddy Simulation ◽  
Blade Root ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

With the ongoing increase in the size of wind turbines, experimental investigations have become more complicated and expensive. Therefore, computational models have proven to be a viable solution for design purposes. This article aims to validate CFD simulations of an experimental model wind turbine (MoWiTO 1.8) using Delayed Detached Eddy Simulation (DDES) and Improved DDES (IDDES) turbulence modelling approaches. For the purpose of validation, integral quantities (such as power, thrust, torque and blade-root bending moment in the flapwise direction) measured in the wind tunnel are compared with numerical results obtained with OpenFOAM. In general, the computational results show a very good agreement with the measurements for most of the monitored quantities. In particular, the blade-root bending moment presents the largest difference, taking into account that the simulation assumes the turbine blades are rigid. Nevertheless, the simulation does achieve in recreating the turbulent behavior as can be evidenced by the Power Spectral Density graphs, and the wake’s velocity measurements. In general, the IDDES turbulent model achieves a better agreement to the experimental results, while maintaining a very similar computational time as the DDES model.

scholarly journals A Dynamic Rotor Vertical-Axis Wind Turbine with a Blade Transitioning Capability

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1446 ◽  
Author(s):  
Elie Antar ◽  
Amne El Cheikh ◽  
Michel Elkhoury
Keyword(s):  
Wind Turbine ◽  
Average Power ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Optimized Design ◽  
Detached Eddy Simulation ◽  
Vertical Axis Wind Turbine ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

This work presents an optimized design of a dynamic rotor vertical-axis wind turbine (DR VAWT) which maximizes the operational tip-speed ratio (TSR) range and the average power coefficient (Cp) value while maintaining a low cut-in wind velocity. The DR VAWT is capable of mimicking a Savonius rotor during the start-up phase and transitioning into a Darrieus one with increasing rotor radius at higher TSRs. The design exploits the fact that with increasing rotor radius, the TSR value increases, where the peak power coefficient is attained. A 2.5D improved delayed detached eddy simulation (IDDES) approach was adopted in order to optimize the dynamic rotor design, where results showed that the generated blades’ trajectories can be readily replicated by simple mechanisms in reality. A thorough sensitivity analysis was conducted on the generated optimized blades’ trajectories, where results showed that they were insensitive to values of the Reynolds number. The performance of the DR VAWT turbine with its blades following different trajectories was contrasted with the optimized turbine, where the influence of the blade pitch angle was highlighted. Moreover, a cross comparison between the performance of the proposed design and that of the hybrid Savonius–Darrieus one found in the literature was carefully made. Finally, the effect of airfoil thickness on the performance of the optimized DR VAWT was thoroughly analyzed.

scholarly journals Prediction and measurement of the aerodynamic performance of a wind turbine

2018 ◽  
Vol 240 ◽  
pp. 04001
Author(s):  
Ali Cemal Benim ◽  
Michael Diederich ◽  
Fethi Gül
Keyword(s):  
Wind Turbine ◽  
Transport Model ◽  
Three Dimensional ◽  
Detached Eddy Simulation ◽  
Simulation Framework ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Shear Stress Transport Model ◽  
Flow Turbulence ◽  
Good Agreement

Aerodynamic behavior of a small wind turbine is analyzed, both experimentally and numerically. Mainly, an unsteady three-dimensional formulation is adopted, where the flow turbulence is modelled by an Improved Delayed Detached Eddy Simulation framework, using the four-equation transitional Shear Stress Transport model, as the turbulence model. A quite good agreement between the measurements and calculations is observed.

Numerical Implementation of Detached-Eddy Simulation on a Passenger Vehicle and Some Experimental Correlation

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
L. Sterken ◽  
S. Sebben ◽  
L. Löfdahl
Keyword(s):  
Flow Characteristics ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Wake Flow ◽  
Computational Time ◽  
Detached Eddy Simulation ◽  
Passenger Vehicle ◽  
Ansys Fluent ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

This study presents an implementation of delayed detached-eddy simulation (DDES) on a full-scale passenger vehicle for three configurations with the use of commercial software harpoon (mesher) and ansys fluent (solver). The methodology aims to simulate the flow accurately around complex geometries at relevantly high Re numbers for use in industrial applications, within an acceptable computational time. Geometric differences between the three configurations ensure significant drag changes that have a strong effect on the wake formation behind the vehicle. Therefore, this paper focuses on the analysis of the base wake region. At first, the paper evaluates the performance of the DDES, where it verifies the different operating conditions of the flow around the vehicle with respect to the DDES definition. In a second step, the numerical results are correlated with force measurements and time-averaged flow field investigations, conducted in the Volvo Cars aerodynamic wind tunnel (WT). The comparison confirms a good agreement between the experiments and the simulations. The resolved flow scales obtained by DDES give a further insight into differences in the wake flow characteristics between the configurations related to their contribution to drag.

Study On the Applicability of URANS, LES and Hybrid LES/RANS Models for Prediction of Hydrodynamics of Cyclone Separator

2021 ◽  
Author(s):  
Sai Guruprasad Jakkala ◽  
S Vengadesan
Keyword(s):  
Fluid Flow ◽  
Flow Characteristics ◽  
Mesh Size ◽  
Turbulent Energy ◽  
Computational Time ◽  
Detached Eddy Simulation ◽  
Reynolds Stresses ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Rans Models

Abstract Cyclone separators are an integral part of many industrial processes. A good understanding of the flow features is paramount to efficiently use them. The turbulent fluid flow characteristics are modelled using URANS, LES and hybrid LES/RANS turbulent models. The hybrid LES/RANS approaches, namely DES (Detached Eddy Simulation), DDES (Delayed Detached Eddy Simulation) and IDDES (Improved Delayed Detached Eddy Simulation) based on the k - $\omega$ SST RANS approaches are explored. The study is carried out for three different inlet velocities (v = 8, 16:1, and 32 m=s). The results from hybrid LES/RANS models are shown to be in good agreement with the experimental data available in the literature. Reduction in computational time and mesh size are the two main benefits of using hybrid LES/RANS models over the traditional LES methods. The Reynolds stresses are observed in order to understand the redistribution of turbulent energy in the flow field. The velocity profiles and vorticity quantities are explored to obtain a better understanding of the behaviour of fluid flow in cyclone separators.

Sign in / Sign up

Export Citation Format

Share Document