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.

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 Effects of inlet velocity profiles for thermal stripping phenomena in T-junctions

2021 ◽  
Vol 2116 (1) ◽  
pp. 012026
Author(s):  
Lisa Lampunio ◽  
Yu Duan ◽  
Raad Issa ◽  
Matthew D. Eaton
Keyword(s):  
Velocity Profiles ◽  
Lower Sensitivity ◽  
Detached Eddy Simulation ◽  
Mean Velocity ◽  
Inlet Velocity ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Flow Domain ◽  
The Mean ◽  
Good Agreement

Abstract This paper investigates the effects of different inlet velocities on thermal stripping phenomena within a T-junction. The computational flow domain is modelled using the Improved Delayed Detached Eddy Simulation (IDDES) turbulence model implemented within the commercial CFD code STAR-CCM+ 12.04. The computational model is validated against the OECD-NEA-Vattenfall T-junction Benchmark data. The influence of flat and fully developed inlet velocity profiles is then assessed. The results are in good agreement with the experimental data. The different inlet velocity profiles have a non-negligible effect on the mean wall temperature. The mean velocity shows lower sensitivity to changes in inlet velocity profiles, whose influence is confined mainly to the recirculation zone near the T-junction.

scholarly journals A DES Procedure Applied to a Wall-Mounted Hump

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Radoslav Bozinoski ◽  
Roger L. Davis
Keyword(s):  
Pressure Coefficient ◽  
Three Dimensional ◽  
Synthetic Jets ◽  
Navier Stokes ◽  
Separation Region ◽  
Detached Eddy Simulation ◽  
Three Dimensional Flow ◽  
Eddy Simulation ◽  
Turbulent Separation ◽  
Good Agreement

This paper describes a detached-eddy simulation (DES) for the flow over a wall-mounted hump. The Reynolds number based on the hump chord isRec=9.36×105with an in-let Mach number of 0.1. Solutions of the three-dimensional Reynolds-averaged Navier-Stokes (RANS) procedure are obtained using the Wilcoxk−ωequations. The DES results are obtained using the model presented by Bush and Mani and are compared with RANS solutions and experimental data from NASA's 2004 Computational Fluid Dynamics Validation on Synthetic Jets and Turbulent Separation Control Workshop. The DES procedure exhibited a three-dimensional flow structure in the wake, with a 13.65% shorter mean separation region compared to RANS and a mean reattachment length that is in good agreement with experimental measurements. DES predictions of the pressure coefficient in the separation region also exhibit good agreement with experiment and are more accurate than RANS predictions.

scholarly journals Numerical Investigation of Powered Jet Effects by RANS/LES Hybrid Methods

2019 ◽  
Vol 37 (3) ◽  
pp. 565-571
Author(s):  
Zhibin Gong ◽  
Jie Li ◽  
Jixiang Shan ◽  
Heng Zhang
Keyword(s):  
Numerical Investigation ◽  
Hybrid Methods ◽  
Three Dimensional ◽  
Jet Flow ◽  
Weno Scheme ◽  
Detached Eddy Simulation ◽  
Turbulent Structures ◽  
Ambient Flow ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation

For the high-precision simulation of engine jet effects, an improved delayed detached eddy simulation (IDDES) method based on the two-equation shear stress transport (SST) model is developed, and the fifth-order finite-volume weighted essentially non-oscillatory (WENO) scheme is employed to enhance accuracy of spatial discretization, and then numerical investigation of powered jet effects by RANS/LES hybrid methods is carried out. The effects of the grid distributions and the accuracy of the spatial schemes are discussed during the RANS/LES validation analysis on the fully expanded jet flow and Acoustic Reference Nozzle (ARN) jet flow. The results show that, by enlarging the grid density and improving the accuracy of the spatial schemes, the velocity distributions in the jet flow can be better predicted, the non-physical steady flow after the jet nozzle can be shortened, the instantaneous flow structures are clearer and the turbulent intensities are more accurate. Then IDDES simulation of turbofan engine jet flow is carried out. The mixing characteristics of the external fan jet flow and internal core jet flow as well as the ambient flow are obtained, and the three-dimensional turbulent structures are also given.

scholarly journals Simulation of transonic buffet with an automated zonal DES approach

2020 ◽  
Vol 11 (4) ◽  
pp. 1025-1036
Author(s):  
Maximilian Ehrle ◽  
Andreas Waldmann ◽  
Thorsten Lutz ◽  
Ewald Krämer
Keyword(s):  
Three Dimensional ◽  
Reynolds Numbers ◽  
Research Model ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Shock Motion ◽  
Convection Speed ◽  
Transonic Buffet ◽  
Simulation Time

Abstract A study of transonic buffet on the NASA Common Research Model at flight Reynolds numbers is presented. The ability of two different hybrid RANS/LES models as well as the URANS approach for resolving three-dimensional buffet motion was evaluated by means of spectral analysis. Automated Zonal DES and URANS simulations show similar results in terms of buffet frequency and spanwise propagation of buffet cells, whereas the Delayed Detached Eddy Simulation results indicate a strong interaction between flow separation and shock motion. The extracted characteristic frequencies which are associated with transonic buffet are located in a range of Sr = 0.2–0.65 for URANS and AZDES and are therefore in accordance with findings from related recent research. Furthermore, the simulation time series were investigated and a structure of spanwise moving buffet cells with varying convection speed and wavelength could be observed.

Sign in / Sign up

Export Citation Format

Share Document