Abstract— Vertical axis wind turbines (VAWTs) have been argued to possess many advantages over the horizontal axis wind turbines (HAWTs) that make them more suitable to complex terrain applications where wind conditions are inherently turbulent. However, due to the complexity of VAWT blade aerodynamics, the available literature on the subject are very limited, leaving a number of VAWT parameters such as λ, solidity, blade number, blade shape and camber to be optimized. Additionally, research on VAWT performance are mostly focused on uniform wind analysis rather than fluctuating. This paper aims to numerically simulate and compare the performance of a 5kW VAWT with cambered- airfoils under uniform and fluctuating wind conditions. The Reynolds averaged Navier-Stokes equations and k-ω SST model were applied through computational fluid dynamics modeling. Results revealed that the fluctuating wind induced detrimental effect to VAWT performance as the cycle-averaged unsteady power coefficient are lower than the optimum steady power coefficient at relatively the same order of tip speed ratio. Generally, the unsteady power coefficient greatly vary with the fluctuating wind and do not follow the steady performance curve of the VAWTs. Camber-bladed VAWT was found to perform better in unsteady wind case with cycle averaged power coefficient of 0.34 versus the straight-bladed VAWT with cycle averaged power coefficient of 0.31. Index Terms—Camber, Unsteady Wind, VAWT, CFD I. INTRODUCTION AJORITY of research and development work is focused mainly on horizontal axis wind turbines (HAWTs), making it a more preferred technology than vertical axis wind turbines (VAWTs) in most large scale wind farms. HAWTs are more efficient aerodynamically than VAWTs but essentially require laminar wind flow or good quality wind energy [1,2]. Results from some recent studies have shown that VAWTs are theoretically more suitable for small scale power generation in urban terrain, where wind Manuscript received January 14, 2016; accepted January 30, 2016. This work was supported in part by the Department of Science and Technology (DOST) under the Engineering Research and Development for Technology (ERDT) Program. M. D. Bausas, M.Sc. is with the Department of Science and Technology as Senior Science Research Specialist for the Tidal Current Energy Integrated Resource Assessment and Spatial Planning Tool Project. (email: michaelbausas@gmail.com). L. A. M. Danao, Ph.D. is an Associate Professor of the Department of Mechanical Engineering, University of the Philippines. (corresponding author, e-mail: louisdanao@coe.upd.edu.ph). conditions are turbulent rather than uniform [2,3]. There are several claimed advantages of VAWTs over HAWTs that make them preferable for such conditions: ability to respond instantaneously to changing incoming wind direction; minimal performance degradation from turbulent wind flow; compact and simple design as some mechanical components can be situated at the base of the turbine, and maximum power coefficient (C P ) is achieved at low tip speed ratios (λ), thus reducing noise and safety issues. Despite having the same order of C P and numerous advantages over HAWT, VAWT still requires proper technology R&D to improve self-starting and optimize wind power extraction. A number of parameters still need to be optimized, such as λ, solidity, blade number, blade shape and, camber as well as constant or variable blade pitch offset [4]. However, due to the difficulty and complexity of modeling VAWT aerodynamics, related technical studies are scarce in literature which mostly deal with experimental and numerical analysis of VAWT performance under uniform wind conditions. McIntosh et al. [5] investigated VAWT response when subjected to fluctuating free stream of sinusoidal nature while running at a constant rotational speed. Results showed that an increase in energy extraction can be attained using a rotational speed greater than the calculated steady state maximum. The over–speed control technique resulted in a 245% increase in energy extracted. Further improvements in the performance can be attained by using a tip speed ratio feedback controller incorporating time dependent effects of gust frequency and turbine inertia giving a further 42% increase in energy extraction. In his study, at low frequencies of fluctuation (0.05Hz) away from stall, the unsteady C P closely tracks the steady C P curve. While at higher frequencies (0.5Hz), the unsteady C P is seen to form hysteresis loops with averages greater than steady predictions. Scheurich and Brown [6] used vorticity transport model to investigate the aerodynamic performance and wake dynamics, both in uniform and fluctuating wind conditions, of three different vertical-axis wind turbines: straight-bladed configuration, curved-bladed configuration and helically twisted blades configuration. The turbines with non-twisted blades are shown to be somewhat less efficient than the turbine with helically twisted blades when the rotors are operated at constant rotational speed in unsteady wind conditions. In steady wind conditions, the power coefficients M The Influence of Blade Camber on the Performance of a Vertical Axis Wind Turbine in Fluctuating Wind Michael D. Bausas, and Louis Angelo M. Danao, Member, IAENG Proceedings of the World Congress on Engineering 2016 Vol II WCE 2016, June 29 - July 1, 2016, London, U.K. ISBN: 978-988-14048-0-0 ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online) WCE 2016