Reduction of electromagnetic interferences in measurements of fast-changing air velocity fluctuations by means of hot-wire anemometer

Abstract

Air flow velocity measurements are the key issues in examining the condition and progress of mine ventilation process. In addition to standard measurements carried out in the stock exploitation process, it is necessary to conduct cognitive scientific research in this area. One of the important issues here is the measurement of fast-changing fluctuations of air velocity, enabling the knowledge of the spectral structure of the tested flow. Hot-wire anemometers are used for such measurements both in laboratories and in industrial conditions. A frequent metrological problem is the presence in the measuring area of a high level electromagnetic interference (EMI) from electrical networks and devices. Due to the metrological properties of hot-wire anemometers, such as high gain and wide frequency bandwidth, measuring signal in the presence of electromagnetic interferences may be subject to strong disturbances. Therefore, it is necessary to develop methods for reducing or eliminating these disturbances. The article presents such a new method based on the use of an additional induction loop in the anemometric sensor for compensation or reduction of interferences.