Wind tunnel tests in preparation for industrialization
The WindBox's operation had already been validated in November 2019 during previous tests, in the same CSTB wind tunnel in Nantes. The fourth version has since been optimized, with a new geometry favoring aerodynamics. An effort has also been made to rationalize the number of parts and assembly time, with a view to deploying the modules.
The wind tunnel tests, supervised by Hervé Brebion and Jean-Paul Bouchet on the CSTB side, and by Yanis Maacha on the WIND my ROOF side, consisted of three tests.
Test 1 - Module performance
Thermal vein
The aim of the first two days was to evaluate the turbine's power output in relation to wind speeds. The WindBox was placed in the center of the vein and exposed to winds ranging from 4 m/s to 20 m/s (i.e. 14.4 km/h to 72 km/h). These tests enabled us to qualify the turbine's energy performance, validating the power curve shown opposite.
Test 2 - Performance and snow resistance
Thermal vein
Performance tests were then carried out under extreme climatic conditions, with temperatures ranging from -5°C to -15°C and with snow generation.
The results enable us to quantify the power loss caused by snow. When the rotor blades are covered with 3 cm of snow, for example, a power loss of 30% is recorded for winds of 8 m/s (28.8 km/h). Temperatures, on the other hand, pose no problems for turbine operation, and do not damage the overall system.
Test 3 - Extreme wind resistance
Aerodynamic vein
The purpose of the final test was to qualify the wind module's resistance to high winds and storms, in order to prevent any risk of tearing or breakage. Resistance was tested along two axes, the first with a frontal wind (0°), the second with a lateral wind (90°). The safety flap is raised to 20 m/s (72 km/h) to stop power generation and secure the WindBox.
In both cases, the target of 50m/s (180km/h) resistance was achieved.
Wind tunnel tests and the impact of these violent winds on the WindBox have highlighted two areas for improvement prior to series production:
- The attachment system for the rear grille and a rotor blade came loose from their supports at 46 m/s (165 km/h), due to the loosening of the bolts holding them in place. On the production version, rivets replace the bolts for optimum strength.
- The mounting feet, welded onto a roof waterproofing model, have plasticized (irreversible deformation). On future installations, a ballast system will reduce stresses due to extreme winds.
Time for industrialization!
These wind tunnel tests validated the performance of the WindBoxes and qualified their resistance to extreme weather conditions. Once the prototype series had been validated, WIND my ROOF set about deploying a machined version with the help of the SEGULA Technologies group, through its subsidiary SIMRA. The teams worked together to deliver the first eight modules in May 2022!
To find out more about this partnership, click here!