Comparison of Computational Results Obtained From a Homogeneous Cavitation Model With Experimental Investigations of Three Inducers

Abstract

The paper presents full 3D numerical simulations and experimental investigations of the cavitating flow through three axial inducers. These inducers are identified by the tip blade angle at the leading edge β1T=8, 10, and 13deg. The numerical and experimental investigations were carried out at the LEMFI laboratory (Laboratoire d’Energétique et de Mécanique de Fluides Interne) of the ENSAM-Paris center (Ecole Nationale Supérieure d’Arts et Métiers). A review of the cavitating regime modeling and the cavitation homogeneous model used for this paper’s calculations is first presented. The numerical model is based on a combination of the multiphase flow equations with a truncated version of the Rayleigh-Plesset model predicting the complicated growth and collapse processes of bubbles. The mass transfers due to cavitation are source/sink terms in continuity equations of the liquid and vapor phases. The cavitation model also features a solution methodology which implicitly couples the continuity and momentum equations together. The main results are presented for the inducers at a range of flow rates and cavitation numbers: (1) Experimental results concerning: (i) the overall performances: Pressure head coefficient and efficiency versus flow rates; (ii) critical cavitation number (5% and 15% of drop) versus the flow rate; (2) Numerical results concerning: (i) the overall performances; (ii) the numerically investigated water vapor volume fraction distributions and other CFD results, which enable us to explain the cavitating behavior for these inducers; (iii) the location and sizes of the blade cavity and backflow vortex. Finally, the comparisons between experimental and simulated results on the overall performances, cavity sizes and cavity location are discussed. A qualitative agreement between experimental and predicted results was found for two inducers for a range of flow rates. The head breakdown in the simulations started at a different cavitation coefficient than that in the experiment.