The basic principle of the anemometer is to put a thin wire in the fluid, and the wire is heated by an electric current to make its temperature higher than the temperature of the fluid, so the wire anemometer is called "**". When the fluid flows through the wire in the vertical direction, it will take away part of the heat of the wire, causing the temperature of the wire to drop. According to the theory of forced convection heat exchange, it can be deduced that there is a relationship between the dissipated heat Q and the velocity v of the fluid. The standard anti-probe consists of two brackets tensioned with a short, thin wire, as shown in Figure 2.1. Metal wires are usually made of metals with high melting points and good ductility such as platinum, rhodium, and tungsten. The commonly used wire has a diameter of 5 μm and a length of 2 mm; the smallest probe is only 1 μm in diameter and 0.2 mm in length. According to different uses, the probe is also made into double wire, three wire, oblique wire, V-shaped, X-shaped and so on. In order to increase the strength, sometimes a metal film is used to replace the metal wire, and a thin metal film is usually sprayed on a thermally insulating substrate, which is called a thermal film probe, as shown in Figure 2.2. **Probes must be calibrated before use. Static calibration is carried out in a special standard wind tunnel, measuring the relationship between flow rate and output voltage and drawing a standard curve; dynamic calibration is carried out in a known pulsating flow field, or adding in the heating circuit of the anemometer. The last pulsating electrical signal is used to verify the frequency response of the anemometer. If the frequency response is not good, the corresponding compensation circuit can be used to improve it.
Julat pengukuran halaju aliran dari {{0}} hingga 100m/s boleh dibahagikan kepada tiga bahagian: kelajuan rendah: 0 hingga 5m/s; kelajuan sederhana: 5 hingga 40m / s; Kelajuan tinggi: 40 hingga 100m/s. Siasatan haba anemometer digunakan untuk pengukuran yang tepat dari 0 hingga 5m / s; probe pemutar anemometer sesuai untuk mengukur halaju aliran dari 5 hingga 40m / s; Dan penggunaan tiub pitot boleh didapati dalam julat kelajuan tinggi * hasil terbaik. Kriteria tambahan untuk pemilihan probe aliran anemometer yang betul ialah suhu, biasanya suhu sensor haba anemometer adalah kira-kira tambah -70C. Siasatan pemutar anemometer khas boleh mencapai 350C. Tiub Pitot digunakan di atas ditambah 350C.
