Hotline Features of Anemometers
The length of the hot wire is generally in the range of 0.5-2 mm, the diameter is in the range of 1-10 microns, and the material is platinum, tungsten or platinum-rhodium alloy. If a very thin (thickness less than 0.1 micron) metal film is used instead of a metal wire, it is a hot film anemometer, which has a similar function to a hot wire, but it is mostly used to measure the flow rate of a liquid. In addition to the ordinary single-wire type, the hot wire can also be a combined double-wire or three-wire type to measure the velocity components in all directions. The electrical signal output from the hotline is input into the computer after amplification, compensation and digitization, which can improve the measurement accuracy, automatically complete the data post-processing process, and expand the speed measurement function, such as simultaneously completing the instantaneous value and time average value, combined speed and partial speed, and turbulence. and other measurements of turbulence parameters. Compared with the pitot tube, the hot wire anemometer has the advantages of small probe volume, small interference to the flow field, fast response, and can measure unsteady flow velocity; can measure very low velocity (such as as low as 0.3 m/s).
