Mechanism and scalability of tip vortex cavitation suppression by water and polymer injection

Abstract

Tip vortex cavitation (TVC) is typically the first form of cavitation observed in propellers; therefore a delay in its onset is sought. TVC suppression via mass injection in the core of the vortex was studied with an elliptical plan-form hydrofoil NACA-66 modified in a recirculating water tunnel with known nuclei distribution. The solutions injected were water and Polyox WSR 301 solution with concentration ranging from 10 to 500pmm. It was observed that TVC was suppressed in all cases where mass was injected. Higher polymer concentration solutions and higher flux rate provided a drop in cavitation desinence of 1.8 Water injection at the lowest flux rate provided the smallest drop in cavitation desinence, 0.03. A saturation effect for the TVC suppression was also observed for both the polymer concentration (125ppm) and volume flux rate (Qjet / Qcore = 0.48). The mechanisms and scalability that lead to TVC suppression via mass injection will be investigated.