Unique study air curtain New Waterway
Deltares is set to carry out a study to optimize the design of an air curtain of bubbles in The Nieuwe Waterweg ("New Waterway"). This air curtain might be used to restrict salinity intrusion at low river discharges. In the laboratories of Deltares in Delft and the Texas A&M University, scale model tests will be performed. In addition, detailed computer calculations will be carried out.
Previous studies carried out by Deltares have shown that an air curtain is a feasible and cost-effective measure to restrict salinity in the Rhine-Meuse estuary. We are now studying how to use this curtain more effectively and in the most energy-saving and cost-cutting way, while taking into account the varying tidal and river discharge conditions in the New Waterway.
For the first time, such air curtain design conditions will be studied and determined in an open estuary. Up to now, air curtains of bubbles to restrict salinity have only been used in Dutch and foreign sluices. From the river soil, air bubbles are being transported into the water by the air curtain. These bubbles are pulling water along while they vertically mix the water and thus restrict salinity.
Adjusting an air curtain requires a delicate touch. Deltares project leader Yann Friocourt: too little injected air will result in a lesser effectiveness of the curtain. Too much air injected will cost a lot of unnecessary energy. Through scale model tests, we want to gain a better understanding of the process of how much air should be transported through the water to obtain sufficient mixing power. In addition, we have to take into account a number of varying circumstances, such as flow rate and level of stratification.
Small-scale air curtain study for the Volkeraksluizen
These tests will lead to an improvement of the calculation models (TRIWAQ and Delft3D). These models are not only suitable for the New Waterway, but also for technical optimisation of air curtains on other locations. Friocourt: There is widespread interest in this project. Salinity is a worldwide problem that will only get bigger in the future because of increased water use and climate change. Air curtains, if adjusted properly, will be an effective way to restrict the salinity intrusion.
In August, tests will be carried out at the Texas A&M University, followed by tests at the Deltares Water Soil Flume in Delft in autumn. The Ministry of Infrastructure and the Environment (Province of Zuid-Holland and DG Spatial Development and Water) and the Port of Rotterdam commissioned this study.
Published:16 August 2012
