Hot Wire Systems
The Technology
Hotwire anemometers are used to measure the flow velocity in gases and in liquids.
Predominantly, they are used to measure unsteady flow effects as they are able to resolve frequencies up to the kilohertz range due to their short response time.
A very thin wire – only a few µm of thickness– is heated electrically. Caused by thermal convection and radiation, this wire emits heat to the environment. The flow around the wire is essential for convection if the temperature of the hotwire is significantly above the surrounding flow temperature.
Using an electrical control circut to keep the wire at a constant temperature (CTA bridges), the required voltage is a direct measure for the speed. The correlation between voltage and speed has to be calibrated for each probe.
Our Solution
For industrial use, as well as for use in a laboratory environment, we have developed an easy to use 4 channel hotwire system. For tracking down of special phenomina, e.g. for flow separation or for Carman vortex flow the signals of the hotwires can be made audible on headphones.
