Abstract

Indirect Methods of Detecting the Beginning of Cavitation in a Flow
A definition of the beginning of cavitation is presented and a comparative description of the results of electric (measurements of the electric resistance of the liquid) and optical (measurements of attenuation of a white light beam) measurements of this effect is given. The measurements were made in a cavitational tunnel adapted for the investigations of ship's propellers (Fig. 2). The cavitation was generated by the reduction of pressure at particular flow velocity. The results of the resistance  measurements  in the flow were presented as a function R=f(σ_cav) (Fig. 5) for five chosen flow velocities. The attenuation of white light beam was measured with a probe of the Author's design (Fig. 4). The results are presented in Fig. 6 as a function i/i₀=f(σ_cav), where i/i₀ is a measure of the light attenuation in the flow. The suitability of the both method for detecting the beginning of cavitation was proposed. Attension was paid also to other method serving the same purpose.