This paper has different parameters of an airfoil (NACA 4412). The results also indicate that the momentum coefficient of 0.05 is sufficient for most of the cases. The aerodynamic coefficients are also more improved by increasing the thickness once the appropriate momentum coefficient is applied. Furthermore, the obtained results reveal that applying the co-flow jet has a positive effect on delaying the stall angle and increasing the lift coefficient. The results of the baseline airfoils show that the NACA 0012 and NACA 0015 airfoils generate a larger lift at small angles of attack where the NACA 0018 and NACA 0021 airfoils produce a higher lift at larger angles of attack. The aerodynamic coefficients along with the lift to drag ratio are calculated and the results are compared with together for the baseline and co-flow jet geometries. To numerically simulate the fluid flow, the Navier-Stokes equations are solved with a transitional turbulence model. The Reynolds number of 1.3 × 10 5, angles of attack between 0°and 18°a nd momentum coefficients of 0.03, 0.05, and 0.08 are considered for four airfoils of NACA 0012, 0015, 0018, and 0021 as the blade sections. This paper investigates the effects of co-flow jet on the aerodynamic performance of some symmetric blade sections of wind turbines. In general, reducing I from the default value of 6.0 to 4.5 is found to increase the turbine CP. When λ reduces from 3.0 to 2.5, the optimal airfoil changes from NACA0018-4.5/2.75 to NACA0024-4.5/3.5, that is increasing the maximum thickness from 18%c to 24%c and its position shifts from 27.5%c to 35%c, while the leading-edge radius index, I, remains 4.5. The results show that the three shape defining parameters have a fully coupled impact on the turbine power and thrust coefficients. The simulations are verified and validated with three experiments. The analysis is based on 252 high-fidelity transient CFD simulations of 126 identical airfoil shapes. The present study performs a combined analysis of three shape defining parameters, namely the airfoil maximum thickness and its position as well as the leading-edge radius, to reveal the overall design space. ![]() The optimal airfoil shape for VAWTs at low λ, where dynamic stall is present, has not yet been studied in the literature, therefore, the present study addresses this gap by focusing on this regime to serve as a step towards designing morphing airfoils for VAWTs by identifying the optimal airfoil shape at low λ. Morphing airfoils can be a potential solution by modifying the airfoil shape to optimal at each λ. ![]() At relatively high wind speeds, which are promising due to high wind power potential, VAWTs operate at low λ with poor power coefficient. The current design of vertical axis wind turbines (VAWTs) suffers from inevitable change in tip speed ratio, λ, in variant wind conditions due to fixed rotor speed.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |