Article
Green & Sustainable Science & Technology
D. De Tavernier, C. Ferreira, A. Vire, B. LeBlanc, S. Bernardy
Summary: The study demonstrates that vortex generators (VGs) can delay or suppress dynamic stall process in unsteady flow conditions, with important factors being VG height and mounting position. Configurations with VGs show a larger loss in normal coefficient when VG effectiveness vanishes, but the flow reattaches quicker and the airfoil recovers easier from deep-stall conditions.
Article
Thermodynamics
Fatemeh Ardaneh, Abolfazl Abdolahifar, S. M. H. Karimian
Summary: The aerodynamic performance of the three-part-blade Vertical Axis Wind Turbine can be significantly improved by using a pitch angle of -2 degrees, leading to an increase in output torque and overall performance enhancement at most tip speed ratios.
Article
Energy & Fuels
Ming Chen, Zhenzhou Zhao, Huiwen Liu, Tongguang Wang, Lingyu Meng, Junxin Feng, Ruifang Jiang, Dingding Wang
Summary: The study proposed parametric and entity models to predict the performance of wind turbine blade sections with VGs, showing high accuracy and universality across different conditions. Experimental validation confirmed strong agreement between modelled and experimental results, demonstrating the potential of the parametric approach in improving research efficiency for VG arrangement on wind turbine blades.
FRONTIERS IN ENERGY RESEARCH
(2021)
Article
Thermodynamics
M. E. Nakhchi, S. Win Naung, M. Rahmati
Summary: The objective of this study is to develop direct numerical simulations (DNS) to investigate the aerodynamic performance and transition to turbulence on wind turbine blades, focusing on the NACA-4412 airfoil. Results show that increasing the angle of attack enhances the shedding of vortex structures from the trailing edge, leading to fully turbulent flow downstream. Furthermore, decreasing the angle of attack delays the separation point along the blade surface.
Article
Engineering, Marine
Ahmed Aboelezz, Hani Ghali, Gamal Elbayomi, Mohamed Madboli
Summary: This paper introduces the application of a guided vane airfoil to control the dynamic stall of a Darrieus vertical axis wind turbine. Numerical simulations and experimental tests are conducted to investigate the effect of the guided vane on the aerodynamics performance of the NACA 0018 airfoil. The results show that the guided vane significantly improves the power output of the wind turbine.
Article
Thermodynamics
Nishchay Tiwari, Pawel Flaszynski, Thanushree Suresh, Oskar Szulc
Summary: The effects of rod-type and vane-type vortex generators on wind turbine applications are investigated and compared. Computational fluid dynamics (CFD) is used to assess the benefits of using rod-type vortex generators to control flow separation on wind turbine airfoils. The comparison shows that rod-type vortex generators can be an alternative to conventional vane-type vortex generators for boundary layer separation control on wind turbine blades.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Thermodynamics
Chengyong Zhu, Yingning Qiu, Yanhui Feng, Tongguang Wang, Hui Li
Summary: Dynamic stall on wind turbines causes highly unsteady and nonlinear aerodynamic loads. This study investigates the combined effect of passive vortex generators (VGs) and leading-edge roughness (LER) on dynamic stall of the NREL S809 airfoil. Results show that LER accelerates separated flow and dynamic stall onset, while VGs delay dynamic stall and reduce aerodynamic hysteresis. Additionally, double-row VGs outperform single-row VGs in improving aerodynamic performance of roughened airfoils.
ENERGY CONVERSION AND MANAGEMENT
(2022)
Article
Chemistry, Multidisciplinary
Junjun Jin, Zhiliang Lu, Tongqing Guo, Di Zhou, Qiaozhong Li
Summary: This study investigates the dynamic stall phenomenon in air-particle flow and the aerodynamic performance variations of aircraft and wind turbine airfoils under different pitching parameters. The research finds that the reduced frequency has little effect on the maximum lift coefficient increment caused by particles, but a larger frequency can enhance the hysteresis effect.
APPLIED SCIENCES-BASEL
(2021)
Article
Thermodynamics
Ahmed M. Elsayed, Mohamed A. Khalifa, Ernesto Benini, Mohamed A. Aziz
Summary: This study investigates the effects of multi-suction jets on the aerodynamic characteristics of the NACA 0012 airfoil at a Reynolds number of 0.54 x 105. Both experiments and numerical simulations were conducted. The results showed that the lift coefficient, drag coefficient, stall angle, and flow separation are influenced by the location of the airfoil surface suction jets, suction pressure values, and the number of suction slots. The study also identifies the optimal control case for flow reattachment.
Article
Chemistry, Multidisciplinary
Xia Li, Xiaoxiao Wang, Haigang Tian, Chengming Wang, Benxue Liu
Summary: A vortex-induced flutter composite nonlinear piezoelectric energy harvester (VFPEH) with symmetrical airfoils on both sides of a cylindrical bluff body is designed to solve the problem of self-energy supply for vehicle-mounted micro-sensors, bridge detection, and other low-power electronic devices. The VFPEH shows better output performance compared to the classic vortex-induced energy harvester (VEH) and flutter energy harvester (FEH) under the same size, thanks to the coupling of vortex-induced vibration and flutter. The VFPEH achieves a maximum output power of 6.47 mW, which is significantly higher than the VEH (0.05 mW) and FEH (0.26 mW), when the wind velocity range is 2 m/s-15 m/s.
APPLIED SCIENCES-BASEL
(2022)
Article
Thermodynamics
Mingrui Zheng, Dong Han, Tao Peng, Jincheng Wang, Sijie Gao, Weifeng He, Shirui Li, Tianhao Zhou
Summary: This paper proposes the concept of energy harvesting based on flow-induced vibration (FIV) for long-distance transport pipelines. By harvesting the fluid kinetic energy in pipelines and converting it into electricity, uninterrupted power is provided for sensors along pipelines, enabling remote monitoring and management at a lower cost. The paper aims to identify the shape features of flow-around structures that enhance FIV and improve energy harvesting efficiency, providing design references for energy harvester geometrical shapes. Numerical studies are conducted to investigate the influence of vortex shedding position on FIV performance, including FIV responses, wake patterns, and energy conversion efficiency. The results show that a more forward vortex shedding position leads to a higher FIV response, and the criterion for the shape feature on the upstream side of the structure that enhances FIV is summarized. The energy conversion efficiency is determined by FIV amplitude, oscillating frequency, and fluid force, and is not completely positively correlated with FIV amplitude. Each structure achieves maximum energy conversion efficiency at a frequency ratio of 0.7.
Article
Energy & Fuels
Hector G. Parra, Hernan D. Ceron, William Gomez, Elvis E. Gaona
Summary: Vortex generators are used to maintain a stable turbulent behavior in aircraft wings and wind turbine blades. By improving the transition from laminar to turbulent boundary layer regime, they prevent abrupt shedding. With the use of fixed vortex generators, HAWT turbines achieve higher energy production.
Article
Engineering, Marine
Qing Wang, Muyao Yu, Deshun Li, Rennian Li
Summary: This study investigates the dynamic stall of the S809 airfoil under a sand-wind environment, which has rarely been considered in previous studies. The simulations reveal that sand particles with a diameter of 10 μm decrease the maximum lift coefficient and drag coefficient by approximately 2.18% and 2.52% respectively compared to clear air. Moreover, a particle concentration of 62.6 g/m3 results in a 6.93% decrease in the maximum lift coefficient. The results also indicate that the decrease in lift and drag coefficients becomes more significant with higher particle concentrations, suggesting reduced efficiency of wind turbines in sand storm weather.
Article
Engineering, Marine
Qiurui Cai, Zhengnong Li, Ricky W. K. Chan, Han Luo, Guodi Duan, Bin Huang, Honghua Wu
Summary: This study investigated vortex-induced vibrations of marine risers in Ocean Thermal Energy Conversion systems. Flume experiments were conducted to measure the cross-flow acceleration of the riser at different current velocities and analyze the corresponding vibration responses. Numerical simulations based on the flume experiments were used for validation. The results demonstrated vortex-induced resonance in the first condition and observed similar vibration responses in the second condition, indicating the excitation of higher-order modes at higher flow velocities.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Mechanics
T. C. L. Fava, B. A. Lobo, P. A. S. Nogueira, A. P. Schaffarczyk, M. Breuer, D. S. Henningson, A. Hanifi
Summary: This study investigates the interaction of several instabilities and the influence of free-stream turbulence on laminar-turbulent transition on a wind turbine blade section. It finds that the turbulence intensity is closely related to the occurrence of transition and the development of instabilities.