Research paper Optimizing the aerodynamic performance of archimedes spiral wind turbines: A parametric study on blade angle and length at constant radius Ahmed Essa Faisal a,b,* , Chin Wai Lim a,c,* , Balasem Abdulameer Jabbar Al-Quraishi d , Jassinnee Milano a,c , Tan Chung Hong a,c a Mechanical Engineering Department, College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, Kajang 43000, Selangor, Malaysia b Department of Mechanical Engineering, University of Al-Qadisiyah, Al-Qadisiyah, 58001, Iraq c Institute of Sustainable Energy, Universiti Tenaga Nasional (The Energy University), Jalan IKRAM-UNITEN, 43000, Kajang Selangor, Malaysia d Engineering Technical College of Najaf, Al-Furat Al-Awsat Technical University, Najaf 31001, Iraq A R T I C L E INFO Keywords: Wind energy Archimedes spiral wind turbine Blade angle Blade length Urban wind turbine ABSTRACT This study explores the effect of variations in blade angle (α) and length at a fixed radius (r) on the aerodynamic performance of Archimedes Spiral Wind Turbines (ASWT), with the aim of enhancing their adaptability and efficiency in variable urban wind conditions. To identify the most effective blade design approach, two para- metric methodologies were evaluated within the same dimensional range to maximize the power coefficient (C P ), where (i) an unconstrained parametric study (FM), in which both blade angle and blade length (L) were allowed to vary simultaneously without geometric constraints, and (ii) a geometrically constrained parametric study (SM), in which blade length (L) was held constant while blade angle was adjusted. The results revealed that the SM approach outperformed the FM approach, with a 6.7 % increase in C P over the reference model (0.22), demonstrating higher aerodynamic efficiency, greater flexibility in blade angle and length adjustment, and deeper insights into the effects of geometric parameters. Based on this methodology, 36 ASWT blade models were designed using SolidWorks 2020 and analyzed using 3D simulations conducted in ANSYS CFX-2020 R2. The power coefficient (C P ), relative to the tip speed ratio (TSR), was employed as the performance metric to assess the performance of each model. The analysis identified SM-23 as the most efficient model, with an L of 140 mm and a blade angle of 80 0 . At a wind speed of 10 m/s, this model achieved a maximum C P of 0.265, representing a 14.67 % improvement over the reference model. These findings highlight the potential of refined ASWT blade designs to enhance performance and support sustainable urban wind energy solutions. Nomenclature Latin symbols C Absolute flow velocity (m/s) Fx Axial force (N) L Blade Length (m) S1 pitch 1 S2 Pitch 2 U Blade linear velocity (m/s) D Blade diameter (m) FD Drag force (N) FDx Drag force component parallel to the flow direction (N) FDy Drag force component perpendicular to the flow direction (N) FL Lift force (N) (continued on next column) (continued ) FLx Lift force component parallel to the flow direction (N) FLy Lift force component perpendicular to the flow direction (N) FN Normal force (N) G k Production of Turbulence kinetic energy. Gω Production of specific dissipation rate Uj velocity vectors along the j directions Ui velocity vectors along the I directions Γ k Effective diffusivity of turbulent kinetic energy Γω Effective diffusivity of specific dissipation rate σ k Diffusion Coefficient η c conversion efficiency η g generator efficiency (continued on next page) * Corresponding authors at: Mechanical Engineering Department, College of Engineering, Universiti Tenaga Nasional, Jalan IKRAM-UNITEN, Kajang 43000, Selangor, Malaysia. E-mail addresses: ahmed.essa@qu.edu.iq (A.E. Faisal), lchinwai@uniten.edu.my (C.W. Lim), balasemalquraishi@atu.edu.iq (B.A.J. Al-Quraishi), jassinnee. milano@uniten.edu.my (J. Milano), chung.hong@uniten.edu.my (T.C. Hong). Contents lists available at ScienceDirect Results in Engineering journal homepage: www.sciencedirect.com/journal/results-in-engineering https://doi.org/10.1016/j.rineng.2025.105785 Received 19 April 2025; Received in revised form 26 May 2025; Accepted 13 June 2025 Results in Engineering 27 (2025) 105785 Available online 13 June 2025 2590-1230/© 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by- nc/4.0/).