Wood, DavidJohn, Itoje Harrison2021-05-122021-05-122021-05-07John, I. H. (2021). Aerodynamic Performance and Starting Behavior of Multi-Bladed Waterpumping Windmills (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.http://hdl.handle.net/1880/113405Windmills for waterpumping typically operate at low speed and high torque owing to their multi-bladed nature. This low Reynolds number, Re, operation, however, complicates the rotor aerodynamic behavior due to the mutual interaction between adjacent blades. While studies on aerodynamic and starting performance of windmills indicate that increasing blade number and airfoil type are critical analysis and design parameters, the low Re behavior of the commonly used cambered blades is still poorly understood. Accordingly, the rotor performance and starting behavior of a cambered, multi-bladed, waterpumping windmill were experimentally and analytically investigated at low tip speed ratios using three-, six-, twelve-, and twenty-four-bladed rotor configurations based on Wegereef’s 1984 blade profile. Comprehensive wind tunnel testings were performed to provide accurate airfoil data at flow conditions typical of the low Re and high angles of attack experienced by windmills during starting. Implementation of the blade element momentum (BEM) with a generally more accurate, helical vortex theory-based tip loss function or otherwise “finite blade function” for very low speed wind turbines other than the commonly used Prandtl tip loss factor provided insights on the blade elements performance and subsequently, the global performance parameters. Wind tunnel and theoretical studies showed that design parameters not limited to solidity impact the rotor performance and starting behavior. Increasing the blade number improves the rotor performance coefficients and starting performance by reducing idling time. Generally, there is good agreement between the wind tunnel measurement results and BEM prediction for the range of tip speed ratio considered, except below the optimal tip speed ratio region. In that region, discrepancies due to solidity effects unaccounted for in the BEM prediction were observed and shown to increase with blade number. The impact of blockage was examined with both low and high blockage wind tunnels and found to be significant. For a given rotor model and varying wind tunnel areas, the blockage effects increase with solidity. Overall, the experiment provided better performance, highlighting the importance of accounting for high solidity in low wind speed aerodynamic performance prediction. Useful preliminary guides are proposed to optimize the windmill rotor design.engUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.WindmillsStartingAerodynamicsWaterpumpingWind TunnelCircular-arc AirfoilsSolidityBEMBlockageEnergyEngineering--Mechanicaldoctoral thesis10.11575/PRISM/38859