Anemometer Construction
Anemometer Also known as anemometer, it is based on the cold impinging air flow taking away the heat on the heating element. With the help of an adjustment switch to keep the temperature constant, the adjustment current is proportional to the flow rate. When using thermal probes in turbulent flow, airflow from all directions impinges on the thermal element simultaneously, which can affect the accuracy of the measurement results. When measuring in turbulent flow, the indication value of the thermal anemometer flow sensor is often higher than that of the rotary probe. The above phenomenon can be observed in the pipeline measurement process. Depending on the design of the managed pipe turbulence, it can occur even at low speeds.
Therefore, the anemometer measurement process should be carried out on the straight part of the pipeline. The starting point of the straight line should be at least 10×D (D=pipe diameter in CM) before the measurement point; the end point should be at least 4×D behind the measurement point. The fluid cross-section must not be obstructed in any way
Rotary wheel probe for anemometer
The working principle of the rotating wheel probe of the anemometer is based on converting the rotation into an electrical signal. First, it passes through a proximity sensor, "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 outlet of the pipeline). 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 the anemometer in the 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.
The practice of measuring the air flow velocity in the pipeline by the anemometer proves 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 air flow velocity measurement in the pipeline is suitable for air measurement by the indirect measurement procedure (grid measurement method).
