Unsteady Pressure Fluctuations in an Inducer

In this investigation, pressure fluctuations in an inducer were observed in order to examine the characteristics of unsteady cavitation at lower cavitation coefficients. From the spectrum analysis, it was confirmed that the pressure fluctuations occurred with the frequency of 0.6×ω_s (ω_s, shaft rotational frequency), 1.0×ω_s, 1.1〜1.3×ω_s and also 2.1×ω_s. The 0.6×ω_s was caused by the rotating phenomena in an inducer rotational direction. The 1.1〜1.3×ω_s was caused by the super-synchronous rotating cavitation. The 2.1×ω_s was caused by rotating cavitation in the counter direction. In addition, the amount of head reduction of the inducer caused by the synchronous cavitation (1.0×ω_s) depended on the cavity pattern of the blades.