Graduation Gijs Ter Meulen: Drag Analysis And Model For Forces And Production

Gijs proudly presenting his MSc. certificate.

We have another bright new MSc. engineer in dredging technology1: Gijs ter Meulen. Tuesday, he presented and defended his thesis on the forces and production of a trailing suction head. For this thesis project he was working at our research and development department at Damen Dredging Equipment2.

Trailing suction hopper dredges have become the tool of the trade for modern dredging contractors. They are versatile, flexible and able to transport sand over great distances. They load their cargo in their holds, by sucking up the sediment from the sea bottom with a big trailing suction head. This head looks like an out of size vacuum cleaner head.

Typical drag head on a railing suction hopper dredge.

Usually, it is very difficult to comprehend what is going on in and around the drag head. There is some laboratory research done, but not all results are freely available. Other knowledge is solely based on the experience of well-seasoned dredge masters. I do have respect for the experience of dredge masters, but their stories are hardly usable for an academic model description. So, Gijs took on the challenge to piece together a model, that satisfies our curiosity and fits with the experiences.

Concise development of the drag head model by Gijs ter Meulen.

For this project, he identified several steps, which we briefly touch upon here:

  1. The processes and forces around the drag head3 were all investigated on their cause and effect.
  2. A model was set up, where each process and their interaction with the others were identified.
  3. One main process in the drag head is the jetting production. A powerful jet of water is injected into the soil and this erodes part of the sediment under the drag head4.
  4. Another main process is the cutting production5. What is not eroded away by the jets, is removed by the teeth at the back of the visor.
  5. As the contribution of the processes to the forces and the production is known, the total performance can be calculated.

Along the way, this gave us very useful insight in the capabilities of the drag head and the trailing system, all the way to the requirements for the propulsion. Now, we will be able to continue to improve our drag heads even further. Any other students who would like to participate in that project are welcome to contact us5.

Gijs takes a new step in his career path. He is going to work for a well esteemed customer of us, so we will see him around in the dredging industry. Thanks Gijs, bon voyage!

Gijs, good luck with your future career in dredging.

References

  1. MSc Offshore & Dredging Engineering, TU Delft
  2. Innovation, Damen Dredging Equipment
  3. Designing Dredging Equipment [OE4671], Vlasblom
  4. Sand erosion with a traversing circular jet, Robert Weegenaar
  5. The Cutting of Sand, Dredging Engineering
  6. Internships, Damen Dredging Equipment

See also

CEDA DMC Presentation On Dredging Innovations In Gdansk

Group photo of delegates attending the combined meeting of CEDA CEC & DMC and MIG on dredging in Baltic Ports. (Credit: CEDA)

Because of other activities these last weeks, my promised post about the DMC presentation had some delay. On October 10th, there was a symposium together with the Marine Institute Gdansk and the CEDA Environmental Commission and the CEDA Dredging Management Commission supported by Gdansk Science and Technology Park and the Baltic Ports Organisation1. The topic of the symposium was ‘Advances in Dredging Technology. My contribution was a presentation as DMC member2 on ‘Dredging technology developments versus requirements’.

Presenting the innovations in dredging technology. (Credit: CEDA)

Although dredging sounds like an old rusty trade, in fact, it is in constant movement and highly innovative when experienced from the inside. At the Dredging Management Commission, we have a separate focus group, that investigates the technological solutions that enable the stakeholders to efficiently manage a dredging project. A lot of ‘booby traps’ in the ‘Checklist For Successful Dredging Management’3 can be handled by applying the right technology. If there are issues with turbidity, e.g. one can apply a component as the ‘Plumigator®’4 attachment for the overflow in a trailing suction hopper dredge to comply with turbidity clauses in the contract. If the project has very narrow allowances for positioning, modern survey and control systems allow surgical precision dredging, to reduce overdredging and corresponding penalties.

All in all, we’ve identified more than 70 innovation over the last ten years, that have found a foothold in the dredging industry. These have been categorised to the field of technology: Components, Equipment, Industries, Initiatives, Methodology, Processes, Systems, Tools. Other descriptions that we’ve attributed to these innovations were their contribution in solving certain problems in dredging management, as they are found in the checklist. And how much effort they require and how much benefit they would yield. These last items are very subjective and still open for debate. More to follow later. But, at least the procedure can be laid out to recommend the best options for tackling certain problems in the ‘checklist.

Fields of technology and contributions to improvements in dredging management. (Credit: CEDA)

We had a good discussion at the symposium about this topic and from the other focus groups (contract management, checklist, etc.). There were also cross-over opportunities with the CEDA Environmental Commission. At least, there are enough leads, that can be used for the next CEDA Dredging Days in Rotterdam.

As an illustration of the long way we’ve came in the dredging industry, the conference room in the control centre of the Port of Gdansk5, was decorated with interesting pictures from the construction of the port.

Historic pictures of dredging works at the construction of the Port of Gdansk.

References

  1. CEDA-MIG Joint Symposium on Advances in Dredging Technology 2018 Supported by GSTP and BPO, MIG
  2. Dredging Management Commission, CEDA
  3. New CEDA paper encourages all parties to dredging contracts to start thinking and keep thinking, CEDA
  4. Plumigator, IHC
  5. Port of Gdansk

See also

Celebration: One Year Of Discover Dredging

Celebrating a memorable day with my favourite traditional stroopwaffles

Today is a day to celebrate and I usually celebrate special occasions with traditional Dutch stroopwaffles. It was one year ago, that I introduced my website Discover Dredging to the public1. There was one ‘unofficial’ post before2, but the announcement for the CEDA Dredging Days was seen thousands of times on LinkedIn and served as a grand opening of my own website. Really, it is my own personal stage to tell stories on dredging. I felt the compulsion to share my experience and events with a wider audience. With the blessing of Olivier Marcus, our Director Product Group Dredging, I was encouraged to set up my  website and start telling bits and bobs about the details of dredging.

At the Hydro 2018 conference in Gdansk, Poland, together with Olivier Marcus

It really is in my job description to share knowledge on dredging. Not only for my colleagues, but also for clients, students and general public. For sure the presentations that I have given at conferences are fun to do and are serious projects to execute. But there are so many little things to discover in dredging. My personal website provides me freedom and flexibility to post my own topics at my own pace.

Selection of topics on soil mechanics for dredging (PSD, CPT, SPT, Clay)

Topics I really like, are the ones, where I can explain part of the dredging process in a simple way. The soil mechanics series comes to mind. But dredge pumps and drives are also a favourite topic for me. Often these topics are related to frequently asked questions I receive in my daily job. The posts now offer me a quick reference in case someone asks me the same thing again. I also refer people to my ‘Chapters’ page a lot. From the web site visit metrics, I see this is slowly getting more hits as a landing page.

And as you may have noticed, I am a sucker for ‘old scrap’, sorry: museums. I really like to discover the origins of our modern equipment and see how people in the old days were able to landscape our current world. Other fun things to write about are the current events: ¡VAMOS!, conferences, CEDA, graduations, Damen.

Selection of other dredging topics (Museums, ¡VAMOS!, Graduation Suman Sapkota)

Looking back on one year of writing on Discover Dredging, I can say, that I still enjoy it. And from the responses, you do it too. Reason enough to continue. You can expect a report on a graduation shortly. I have an interesting book recommendation for you. Here in the Netherlands we are going to celebrate Saint Nicholas Day; it will be in time to put it on your wish list. There are still some exhibits from the Damen Dredging Experience to be explained. And there will always be some other topic emerging for publication. Check here regularly or follow me on LinkedIn.

OK, as a small party gift for an anniversary, I still have this colouring page lying around. I used it once in a presentation, but don’t have any specific use for it in a particular topic. I think it is fun enough to share it with you anyway. Have fun!

Colouring page of a dredging equipment toolbox dredge

References

  1. Countdown to the CEDA Dredging Days 2017
  2. Discover Familiar Grounds in Dredging

See also