PSI - Issue 47

Bayu Anggara et al. / Procedia Structural Integrity 47 (2023) 675–684 Bayu Anggara, Dominicus Danardono DPT*, Eko Prasetya Budiana / Structural Integrity Procedia 00 (2019) 000 – 000 2

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1. Introduction Climate is one of the vital structures of life on earth, influencing various parts of human life. Human activities on land cause climate variables to change in an alarming direction. The temperature and rainfall that we face every day are influenced by greenhouse gas emissions that continue to increase, and these changes will affect human life and the environment in the future. The need for renewable energy has received serious attention to reducing climate change caused by fossil energy sources such as coal and oil. Fossil energy sources are still the most significant contributor to the availability of global electrical energy Jacobson (2009). Wind energy is renewable with clean characteristics and is available all year round. In 2015, solar energy and wind energy accounted for 77% of total global renewable energy as a whole Sahu (2018). The wind's kinetic energy is converted into electrical energy through a wind energy conversion device, namely a wind turbine. In general, wind turbines are classified into two types based on the position of their axis, namely HAWT (Horizontal Axis Wind Turbine) and VAWT (Vertical Axis Wind Turbine). Compared to HAWT, VAWT has advantages: low manufacturing and maintenance costs, no yaw system, and can absorb wind from all directions Jin et al. (2015). However, this type of VAWT turbine has the disadvantage of producing relatively low power compared to HAWT. One type of VAWT widely used is the Darrieus H Rotor type wind turbine, which has a simple blade type with straight geometry Ã, Ting, and Fartaj (2008). This turbine works on a lift-based principle. This lift force limits the drag force and generates a tangential force, producing electric energy on the generator Peng, Liu, and Yang (2021). Efforts to improve the efficiency of darrieus wind turbines today are continuing. Darrieus wind turbines can work on low and weak wind speeds but have weaknesses compared to horizontal wind turbines in aerodynamic performance Alqurashi and Mohamed (2020), Battisti et al. (2018). Current turbine blade challenges are aerodynamic stall and wake losses (separated flow). It explained that one of the challenges for the darrieus wind turbine was the dynamic stall phenomenon. Dynamic stall is a phenomenon of loss of lift at a certain angle of attack that causes the performance of the darrieus wind turbine also to fall. Simão Ferreira et al. (2009) explained dynamic stall is the inherent effect of the operation of VAWT when the tip speed ratio is low (λ / 5), which will significantly impact load and power. The addition of a vortex generator to the turbine to prevent flow separation has been carried out several times by previous studies. The vortex generator (VG) on the NACA 4415 airfoil works by controlling the separation of the boundary layer to improve the aerodynamic performance of the airfoil Fouatih et al. (2016). Investigation on NACA 63 (3) -618 also revealed that VGs increased the lift coefficient by 28% and the stall angle by 6.5 ° compared to the clean airfoil Mueller-vahl et al. (2012). Meanwhile, another type of vortex generator, the micro vortex generator (MVG), with a triangular shape and counter-rotating configuration, can function well in delaying boundary layer separation Yashodhar et al (2016). Analysis of aerodynamic and vortex characteristics in wind turbines, and their relation to the effects of spacing on vortex generators and their ability to control the flow that occurs in turbines Li et al. (2019).

Nomenclature Cp

coefficient of power coefficient of moment

Cm

rotor diameter wind velocity

D V Β

tab angle

azimuth angle

θ

operational frequency

Ω

fluid density tip speed ratio

ρ λ

pressure

P

High Efficiency Vortex

HEV