EROSION IN CONICAL DIFFUSERS IN PARTICULATE-LADEN CAVITATING FLOW

This paper highlights the serious damage that can occur in diffusing s ections of pipework in which a cavitating particulate-laden fluid is f lowing. The combined effects of particle erosion and cavitation are sh own to remove considerably more material than would be expected from s umming the effects of the individual mechanisms. It is demonstrated th at, to be sure of avoiding this accelerated surface erosion, the trans ition from a smaller flow section to a larger one needs to be an abrup t expansion. If pressure recovery is important, a possible design solu tion is proposed. In the case of swirling flow, the expansion again ne eds to be abrupt. Evidence was also obtained which showed that, by all owing air to be entrained into the low pressure region in the flow, th e cavitation and the erosion can be substantially reduced.