Application of blade element momentum theory with guaranteed convergence to analyze a straight-blade horizontal axis wind turbine

Abstract Blade element momentum theory continues to be widely used in the wind industry to calculate and analyze wind turbines. This theory has been improved many times to address its inherent weakness of convergence capability. This article applies the one variable BEM method, which has been further improved to help ensure convergence to apply analytical calculations for small horizontal-axis straight-blade wind turbines. This type of turbine has much potential for practical applications, providing electricity to households and residential areas far from cities, but has not been fully researched. Straight-blade turbines with relatively large Re changes in blade spanwise direction often cause difficulties in the convergence of BEM algorithms. This article presents the ability to apply improved BEM theory to straight-blade wind turbines in the wind speed range from 5 to 7 m/s and tip speed ratio from 4 to 7 through analytical calculations. A well-validated CFD model was also performed to evaluate the reliability of the calculation method. The obtained results show that the improved BEM method can be applied to calculate the mechanical power output of straight-blade turbines with errors of less than 10% compared to reality. This thereby proves the applicability of the improved BEM method to solve practical problems of small wind turbines.