The application of actuator-disk momentum models to highly loaded vertical axis rotors (large tip speed ratios/solidities) frequently results in a convergence failure of the iterative method employed and the production of nonphysical erratic solutions. It is suggested that this convergence failure is due to an inflection in Glauert’s empirical fit for streamwise momentum loss versus disk blockage. The erratic solutions are found to be due to the presence of multiple roots occurring near stall between the blade-element and the momentum models. A new method is proposed that employs a graphical root finding scheme coupled with knowledge of a blade’s flow history to correctly identify the turbine’s operating point, regardless of disk loading.

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