Demonstration station for open water channel flow

Sammanfattning: Once a year an event is being held at the fluid physics lab at KTH. One of the main purposes of this event is to awaken an interest in the visiting students from other universities, by demonstrating fluid physics phenomena. Showing the transition from laminar to turbulent flow in an open water channel is one of the demonstrations. This will give the students a feel for the theoretical Reynolds number. The existing water table used for this purpose was lacking in some areas. The purpose of this project is to construct, design and test a rig for openwater channel flow which can be used for the event in the coming years.The character of the flow in an open channel depends on the velocity of the fluid. When the velocity get to a critical level, the flow shifts from a laminar to a turbulent one. It is however difficult to see water flows with the naked eye which makes it difficult to demonstrate this phenomena. There are ways to solve this, that is whatis called flow visualisation. In this project a visualisation method using small hydrogen bubbles in the flow as tracer particles is investigated. The channel design and the visualisation method are investigated experimentally and documented and also compared to existing theory within these areas. The results are deemed satisfactory and the method is documented for further work.