Several Test Methods of Digital Anemometer
The digital anemometer test includes the test of the average wind speed and the test of the turbulence component (wind turbulence 1 ~ 150KHz, different from the fluctuation). The methods for testing the average wind speed include thermal type, ultrasonic type, impeller type, and pick-up tube type, etc.
This method is to test the resistance change when the sensor is cooled by the wind when it is powered on, so as to test the wind speed. No information on wind direction can be derived. In addition to being easy to carry and convenient, the cost-performance ratio is high, and it is widely used as a standard product of anemometers. The elements of thermal anemometers use platinum wires, thermocouples, and semiconductors, but our company uses platinum coiled wires. The material of platinum wire is the most stable material. Therefore, there are advantages in long-term stability as well as in temperature compensation.
The wind direction sensor of the photoelectric anemometer adopts a low-inertia light metal wind vane to respond to the wind direction, and drives the coaxial code disc to rotate. The code disc is coded by Gray code and scanned by photoelectricity, and outputs an electrical signal corresponding to the wind direction.
The photoelectric wind speed sensor uses a low-inertia wind cup, which rotates with the wind, drives the coaxial cutter to rotate, and outputs pulse trains with photoelectric scanning, and outputs the pulse frequency corresponding value corresponding to the number of revolutions, which is convenient for collection and processing. High strength, good starting, in line with national meteorological measurement standards;
The wind direction sensor has a built-in electronic compass to automatically locate the direction angle, which can be installed in fixed places or mobile places (such as special vehicles, ships, drilling platforms, etc.)
Rotary Probe for Anemometers
The working principle of the rotating wheel probe of the digital anemometer is based on converting the rotation into an electrical signal. First, it passes through a proximity induction head, "counts" the rotation of the rotating wheel and generates a pulse series, and then converts it through the detector to obtain the rotational speed value. The large-diameter probe (60mm, 100mm) of the anemometer is suitable for measuring turbulent flow with medium and small flow rates (such as at the pipe outlet). The small-caliber probe of the anemometer is more suitable for measuring the air flow where the cross-section of the pipe is more than 100 times larger than the cross-sectional area of the exploration head.
Positioning of digital anemometer in air flow
The correct adjustment position of the rotor probe of the anemometer is that the airflow direction is parallel to the axis of the rotor. When the probe is turned slightly in the air flow, the indicated value will change accordingly. When the reading reaches the maximum value, the probe is in the correct measurement position. When measuring in the pipeline, the distance from the starting point of the straight part of the pipeline to the measuring point should be greater than 0XD, and the influence of turbulent flow on the thermal probe and pitot tube of the anemometer is relatively small.
Measurement of air flow velocity in pipeline by digital anemometer
Practice has proved that the 16mm probe of the anemometer is the most widely used. Its size not only ensures good permeability, but also can withstand a flow velocity up to 60m/s. As one of the feasible measurement methods, the airflow velocity measurement in the pipeline is suitable for air measurement by the indirect measurement procedure (grid measurement method).
