UVF Unité de Visualisation du Flux de Bulles d'hydrogène
The Hydrogen Bubble Flow Visualization Unit, "UVF", is a particularly useful unit to understand the complex flow patterns associated to water passing around solid bodies.
The Hydrogen Bubble Flow Visualization Unit, "UVF", is a self-contained unit designed to study different flow patterns through the hydrogen bubble flow visualization technique.
Bubbles are generated by electrolysis by the application of an electric current between one cathode (thin thread of platinum) and oneanode (plate of steel), immersed in a flow of water. Hydrogen and oxygen are separated from water by electrolysis, being the hydrogen bubbles generated in the cathode. Since these bubbles are small, they are easily swept by the flow of water.
The electrolysis is performed in a shallow working section (adjustable) with black base to optimize the visualization of the flow patterns.
This working section is located inside a water storage tank, where there is a submersible adjustable speed pump, which will impel water along the working section. By regulating the flow, the user can change the water flow along the working section from laminar to turbulent.
A flow rectifier makes the flow uniform and with little turbulences.
The electric current can be applied continuously. The intensity can be regulated, thus the size of the generated hydrogen bubbles can be varied or the corresponding quantitative measurements can be carried out. The bubbles can be "switched on" or "switched off" by pulses.
Pulses and intervals are independently variable and are indicated in the screen.
To observe the flow separation and the vortex formation clearly, the unit includes different interchangeable models. They are bodies that exert resistance and modifications of the cross section that are introduced in the working section to study the surrounding flows and the passing flows.
For an optimum visualization of the flow patterns there is an adjustable lighting system, located at the side of the working section, which makes hydrogen bubbles shine.
Des exercices et pratiques guidées
EXERCICES GUIDÉS INCLUS DANS LE MANUEL
- Visualization of the flow around different obstacles.
- Understanding laminar and turbulent flow.
- Boundary layer separation and vortex formation.
- Analogies with the aerodynamic flow.
PLUS D'EXERCICES PRATIQUES À EFFECTUER AVEC CETTE ÉQUIPEMENT
- Two-dimensional visualization of the hydrogen bubble flow.
- Quantitative analysis of the flow parameters with little bursts of bubbles.
- Visualization and demonstration of the boundary layer.
- Demonstration of Karman vortices.
- Visualization of flow around models created by the user.
- Presentations with flow patterns recordings using a video camera or webcam (not supplied).