Using CFD to develop new dragheads
CEDA Dredging Days 2017 - Sustainable Dredging - Continued Benefits
van Spaendonk B.A.W., Kuypers R.H.A., Bijvoet E.C.J., van der Blom E.C.
Abstract: A drag head is one of the key components in a trailing suction hopper dredger, as it can have strong influence on the production of an entire dredging vessel. Optimizing the drag head production contributes directly to the overall production. It is for that reason that drag heads are since long subject of research and many different concepts and appearances of drag heads have been developed over time.
Understanding how a drag head works and how its production can be optimized is however a difficult task. Inside a drag head several processes take place, often interfering with each other. One of the processes is erosion, due to the water flow around the edges of a drag head. Another process is mixture forming, one of the most essential but also one of the most difficult to understand. The development of new CFD techniques for soil-water mixtures provide useful tools for better understanding of the processes inside a drag head. Royal IHC uses CFD techniques to model different types of drag heads. With these models the processes and flows inside a drag head are studied. This provides useful insight and a basis to develop new drag head concepts that are able to deliver higher production or are suitable for difficult soil types like clay.
The paper describes the work that has been done on modeling and verification of the different processes that take place inside a drag head. Results of CFD simulations of drag heads will be shown. The paper will also present some of the new types of drag heads that have been developed recently, with special attention for the newly developed clay drag head. Results from full scale prototype tests in operational conditions will be presented if available.
Key words: draghead, design, CFD soil model, clay