Comparison of Theoretical and Experimental Results from the Operation of An Aerator in A Chute

Instituto de Ingeniería, Universidad Nacional Autónoma de México, México

Abstract: In this work, the results of the measurements made in a physical model of a chute with two-phase aerated flow are presented. The aim is to compare the results of an existing theoretical criterion, with the results measured in the laboratory by means of updated measurement equipment, which allows better corroboration of the reliability of the theoretical criterion. To measure the air content in an air-water biphasic flow a physical model was used that simulates the Huites dam, Mexico, where, to diminish the effects of scale, it was built at 1:21 scale. Given the difficulties of making measurements in prototypes and the restrictions to represent the behaviour of the air with the current techniques of CFD, a conductivity probe was designed to measure the air content in a reliable, easy-to-manufacture way that allows measurement in models. The air measurements were processed using the technique of adaptable thresholds to obtain reliable records and these were compared with the equation proposed by Kramer [10]. This study focuses on the concentration of air near the bottom which is a site where a minimum concentration is required to avoid damage by cavitation. In addition to the agreement between measurements and calculations, the results show that there are difficulties in defining the thickness of the bottom layer which need to be considered to avoid cavitation.