Hydraulic Model Studies for Suction Cutterheads

Abstract

The maintenance and deepening of existing waterways and navigational channels by dredging are vital to the nation's economy. Cutterhead dredges share the major burden of dredging in the United States. Sediments in the waterways have become polluted over the years and this has become a matter of concern. A substantial increase in turbidity has been observed in the vicinity of cutterhead dredges. A need exists, therefore, to study the complex nature of flow around the cutterhead, and to investigate the factors contributing to turbidity generation and ways of reducing the turbidity. Hydraulic model studies provide an ideal tool for studying the flow around a cutterhead. Systematic studies of cutterhead design carried out in the past decade were mainly related to the establishment of a similitude criteria for flow at the suction intake of a cutterhead, the sediment pickup behavior at the intake of a suction pipe, and the cutting ability of cutterheads of different shapes. Previous investigations were extended in the current investigation to include studies on flow field and sediment pickup at the cutterhead intake. The flow field studies provide a means to predict velocity field at the cutterhead intake. The sediment pickup phenomenon was found to follow the Reynolds type similitude relationship. The study on sediment resuspension at the cutterhead has helped to identify various parameters related to the sediment resuspension mechanism at the cutterhead.