roombeek rotors
Sculpture in the water, commissioned by Impact and waterschap Regge en Dinkel
A study was made to use the available quantity and speed of the water in the Roombeek in a sculpture. Because the amount of water differs from almost zero to 150 liter per second but generally is about 5 liter only a limited amount of mechanisms were feasable for a kinetic sculpture.
First studies were done with differently shaped rotors with symbols written on them. The sculpture stresses the coherence of nature and science, in the water the mathematical symbols can be seen. The symbols are all part of the equations that are used with water studies such as Bernouilli, energy equations.
Darreus rotors can act with low waterspeeds. They are less efficient than rotors in high pressure turbines but will do for a sculpture. Also they can handle the difference in quantity of water well.
Darreus like rotor. It turned out that the hollow shapes did not function very well, the water just flowed through the rotor without moving them. Impeller like shapes did not work at all, which was to be expected because they demand high speeds to function.
Cog like shapes worked very well but were dismissed as too predictable, too mechanical. Other forms were tried and the irregularity of the triangles appaered to be interesting.
Test model with wood rotors. The triangular rotors show some irregularity in their movement which makes the sculpture more realistic.
The shape also has practical considerations: the turbine like shapes are difficult to weld, triangles are much easier. The bearing is simply a hole with enough play that allows the sculpture to follow the water level. It also does not get damaged like a ball bearing a nylon bearing would because of rust, corrosion or collecting dirt inside. This construction is much more "hufterproof", resistent against misuse. However it took a lot of testing before the proper places and sizes were determined. A test model was made out of wood, with the same weights and dimensions as the (hollow) steel rotors would have. The introduction of a tilted plate behind the entrance also improved the working very much.
The final sculpture
youtube:
test 1 test with 6 wooden rotors, similar size and weight as the final rotors. some unpredictable movements
test 2 4 different shapes, irregular shapes
test 3 3 similar shapes, result predictable