The components of the anemometer are as follows
The anemometer is based on the cold impact airflow taking away the heat from 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 a thermal probe in turbulent flow, airflow from all directions hits the thermal element simultaneously, affecting 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 wheel probe. The above phenomena can be observed during pipeline measurement. Depending on the design of how pipe turbulence is managed, it can occur even at low speeds.
Therefore, the anemometer measurement process should be carried out on the straight part of the pipe. The starting point of the straight line part should be at least 10×D (D=pipe diameter, unit: CM) in front of the measuring point; the end point should be at least 4×D after the measuring point. There must be no obstruction in the fluid section
Rotary probe for anemometer
The working principle of the anemometer's wheel probe is based on converting rotation into electrical signals. First, through a proximity induction start, the rotation of the wheel is "counted" and a pulse series is generated, which is then converted and processed by the detector. Get the speed value.
The large-diameter probe (60mm, 100mm) of the anemometer is suitable for measuring turbulent flows with medium and small flow rates (such as at the pipe outlet). The small-diameter probe of the anemometer is more suitable for measuring airflow 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 anemometer's wheel probe is when the airflow direction is parallel to the wheel axis. When the probe is gently rotated in the air flow, the indication value will change accordingly. When the reading reaches the maximum value, the probe is in the correct measuring position. When measuring in a pipeline, the distance from the starting point of the straight part of the pipeline to the measurement point should be greater than 0XD. The impact of turbulent flow on the thermal probe and pitot tube of the anemometer is relatively small.
The anemometer's practice of measuring air flow velocity in a pipeline has proven that the 16mm probe of the anemometer is the most versatile. Its size not only ensures good permeability, but also can withstand flow rates up to 60m/s. As one of the feasible measurement methods, air flow velocity measurement in pipelines, indirect measurement procedures (grid measurement method) are suitable for air measurement.
