The largest wind tunnel in Europe is located in the Netherlands. The DNW, the German-Dutch Wind Tunnel, was built to perform various aerodynamic tests on large objects. The first test on a model wind turbine with a diameter of 4.5 meter was completed in December 2006, with great success Further data analysis will demand much more work.
Last December, the Energy research Centre of the Netherlands (ECN) performed unique experiments on a wind turbine in the largest European wind tunnel, the DNW in the Netherlands. The purpose of these experiments was to study the wind turbine’s aerodynamic characteristics. This will enable ECN to reduce design risks and increase wind turbine output. The analysis of the results of the tests is still incomplete, but we expect that we will continue to use the data from this test for years to come.
DNW wind tunnel, where the tests on the model were performed.
Herman Snel and Gerard Schepers, scientific researchers at ECN: "The dimensions and complexity of wind turbines have increased significantly over the past few years. This means that manufacturers need more reliable design software. The aerodynamic models in existing computer programs contain too many unknown elements. In order to reduce the design risks and costs, these unknown elements must be dealt with. That can only happen by performing detailed measurements on the rotor blade."
Over the past few years, field measurements have been performed in regions around the world. Unfortunately, it is difficult to distil usable data from these measurements. This is due to fluctuating wind speeds and directions in the free atmosphere, which leads to a large uncertainty when interpreting the data. In a wind tunnel it is possible to control constant wind speeds and directions. A disadvantage of most wind tunnels is that small models of the wind turbines must be used by which the results are not representative for full scale dimensions. For this reason the wind tunnel needs to have giant dimensions.
Photo of wind turbine test set-up in the wind tunnel.
The measurements were performed in the context of the EU project “MEXICO: Measurements and EXperiments In COntrolled conditions". The experiment consisted of instrumenting a 4.5m diameter rotor, which was then placed in the DNW wind tunnel, the largest tunnel in Europe, with a test section of 9.5 x 9.5 m2. Then an extensive measurement programme to measure the pressure on the blades as well as the details of the air flow around the blades and rotor was performed.
Snel and Schepers: "We had planned to test in August 2005, but the test model that was delivered to the Netherlands from Israel had a considerable amount of damage. This caused a year’s delay to the project. The main problem was the lease term on the wind tunnel. There are only a few large wind tunnels in the world, and all of them have an overfull schedule. It wasn’t possible to move our project to August 2006, and 2007 was not an option. One of the sponsors, the European Commission, set the absolute deadline for the project to 31 December 2006. We were able to finish testing just in time in December."
The experiment was performed in the middle of December 2006, and has already produced very unique findings. The project was performed by a consortium of nine research partners in five countries, including Denmark, Sweden, Greece and Israel. ECN is the project co-ordinator.
Link:
Energy research Centre of the Netherlands (ECN)
Final report Mexico project
Movie Wind turbine experiments MEXICO-project
Contact:
Herman Snel,
ECN Wind Energy
0224 - 56 4170
snel@remove-this-part-ecn.nl
Gerard Schepers
ECN Wind Energy
0224 – 56 4894
schepers@ecn.n
