A theoretical and experimental analysis of regenerative blowers

Varella, Sebastiao (1981) A theoretical and experimental analysis of regenerative blowers. University of Southampton, Doctoral Thesis.

Abstract

Regenerative turbomachines have been widely used as pumps since the middle of the twenties and more recently as blowers or compressors, although no ultimate design method has been reached. A comprehensive literature review was carried out, in order to define the most significant theory which was concluded to be the circulatory one. An improvement to one of the reviewed prediction methods has been made by the inclusion of blade number, dynamic slip, reverse flow and expansion chamber effects and a computer program based on this proposed method was written. In the experimental part two main discoveries were made which are the inclusion of an expansion chamber in the stripper, giving a substantial improvement in the blower performance, and the presence of reverse flow when the blower was operating under off-design conditions. From the experiments the shock (impact) losses and the dynamic slip mechanism were also clarified. The results of the theoretical prediction, using the developed method, were compared with the experiment and good agreement was obtained for the design point. The main advantage of this method is the inclusion of the number of blades and its effect on performance, which until now has never been included in any of the published methods. Another advantage is the use of coefficients depending on the geometrical characteristics of the machine and not totally upon experimental results, as is common practice in the other methods. An increase in the hydraulic efficiency from 38% to 52% (isothermal efficiency - 48%) was obtained with the introduction of a series of modifications.

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