Effect of Macroscopic Turbulent Gust on the Aerodynamic Performance of Vertical Axis Wind Turbine

Lakshmi Srinivasan, Nishanth Ram, Sudharshan Bharatwaj Rengarajan, Unnikrishnan Divakaran, Akram Mohammad and Ratna Kishore Velamati ()
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Lakshmi Srinivasan: Department of Mechanical Engineering, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
Nishanth Ram: Department of Mechanical Engineering, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
Sudharshan Bharatwaj Rengarajan: Department of Mechanical Engineering, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
Unnikrishnan Divakaran: Department of Mechanical Engineering, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India
Akram Mohammad: Department of Aerospace Engineering, King Abdulaziz University, Jeddah 21589, Saudi Arabia
Ratna Kishore Velamati: Department of Mechanical Engineering, Amrita School of Engineering Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore 641112, India

Energies, 2023, vol. 16, issue 5, 1-24

Abstract: Vertical Axis Wind Turbines (VAWTs) have proven to be suitable for changing wind conditions, particularly in urban settings. In this paper, a 2D URANS (Unsteady Reynolds-Averaged Navier Stokes) numerical analysis is employed for an H-Darrieus VAWT. A turbulent domain is created through systemically randomising the inlet velocity to create macro-turbulence in front of the VAWT. The parameters for spatial and temporal randomisation of velocity and its effects on the turbine performance are studied for a mean free stream velocity, U ∞ = 10 m/s, and a tip speed ratio (TSR) of 4.1. The mean Coefficient of power (C p ) for randomised fluctuation of 2 m/s and half-cycle randomisation update frequency is 0.411 and for uniform inlet velocity is 0.400. The C p vs. Tip Speed ratio plot suggests that the optimal tip speed ratio for operation is around 4.1 for this particular wind turbine of diameter 1 m, chord 0.06 m, and NACA 0018 airfoils. The effect of randomisation for tip speed ratio λ = 2.5, 3.3, 4.1, and 5.3 on the performance of the turbine is studied. Turbine wake recovers at a faster rate for macro-turbulent conditions and is symmetric when compared to wake generated by uniform velocity inlet. The maximum velocity deficit for a distance behind the turbine, x/d = 8 at TSR (λ) = 4.1 is 46% for randomised inlet and 64% for uniform inlet. The effect of randomisation for λ = 2.5 to 5.3 on the performance of the turbine is analysed. A time-varying gust based on International Electrotechnical Commission (IEC) Extreme Operating Gust is used to study the effect of fluctuating wind conditions in a turbulent environment. Since real-time conditions often exceed gust factors mentioned by IEC, winds with large gust factors such as 1.50, 1.64, and 1.80 are analysed. With an increase in gust amplitude, U gust = 6 m/s to U gust = 12 m/s on a free stream velocity of U∞ = 10 m/s, the mean C p decreases from 0.41 to 0.35 since the wind turbine operates under tip speed ratios outside optimal range due to large fluctuations in incoming velocity.

Keywords: vertical axis wind turbine; gust; macroturbulence; URANS (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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