Cavitation Characteristics of Restriction Orifices (Experiment for Shock Pressure Distribution by Cavitation on Restriction Orifices and Occurrence of Cavitation at Multiperforated Orifices Due to Interference of Butterfly Valve)

Abstract

This paper presents two experimental investigations for cavitation characteristics of restriction orifices. The first experiment is about the spatial distribution of cavitation shock pressure in a pipe at the downstream of restriction orifices. The second experiment is the investigation of butterfly valve throttling to the cavitation in a multiperforated orifice installed piping. From the results of the experiment for the cavitation shock pressure, it is concluded the maximum shock pressure remarkably increases with the decrease of cavitation number regardless of the orifice types. The maximum shock pressure becomes smallest on cone type orifice, and largest on single hole orifice. Multiperforated orifice is between this two. The results of the experiment for occurrence of cavitation due to the interference of butterfly valve show that the cavitation occurs at a relatively high cavitation number when the multiperforated orifice is placed at 1D downstream of the butterfly valve. The butterfly valve throttling accelerates the cavitation at the multiperforated orifice because of the closed orifice installation.