Flow and cavitation characteristics of a damping orifice in water hydraulics

The flow in damping orifices when using water as the working media is of high Reynolds number and cavitation is inevitable. In this article, experimental studies are made on the flow and cavitation characteristics of water hydraulic orifices and the coefficient formulae in previous documents are testified with the Reynolds number ranging from 10(4) to 10(5). All the orifices are made of transparent materials, so the flow and the occurrence process of the cavitation can be observed with the naked eye. The experiments for each orifice are carried out under the two cases with and without backpressure, respectively. Experimental results show that the flow coefficient with backpressure is larger than the case without it. The larger the aspect ratio, the less the flow characteristics are influenced by backpressure. The cavitation first occurs at the inlet of orifices and then shifts to the outlet gradually. When there is cavitation happening at the outlet, flow saturation emerges simultaneously.