The Doppler flow sensor is a completely independent portable sensor that can simultaneously record multiple parameters such as instantaneous flow rate, total flow rate, flow rate, pH value and downhole temperature in the pipeline.
The measurement principle is based on the Doppler effect in physics. According to the acoustic Doppler effect, when there is relative motion between the sound source and the observer, the sound frequency experienced by the observer will be different from the sound source. Frequency of. This change in frequency due to relative motion is proportional to the relative speed of the two objects.
In the Doppler ultrasonic flow measurement method, the ultrasonic transmitter is a fixed sound source, and the solid particles moving with the fluid act as an “observer” that moves relative to the sound source, and the solid particles are incident on their surface The ultrasonic wave is reflected back to the receiver, and the frequency difference between the transmitted sound wave and the received sound wave is the Doppler frequency shift of the sound wave due to the movement of solid particles in the fluid.
Since this frequency difference is proportional to the fluid flow rate, the flow rate can be obtained by measuring the frequency difference, and then the fluid flow rate can be obtained.
At present, Doppler flow sensors are generally used in conjunction with area/rate sensors. The sensors are equipped with ultrasonic transmitters and water depth pressure sensors, which are used to detect the instantaneous flow rate of liquid and the area of ??water passing, respectively, and then derive the instantaneous flow rate.
In the second half of 2006, the Beijing Drainage Group Pipe Network Branch Company decided to use this type of flow sensor to conduct a flow monitoring test in a local watershed sewage pipe network of Qinghe Wastewater Treatment Plant. Its purpose is to accumulate the installation experience of this type of flow sensor and test its specific Performance, understand and master the law of the increase and decrease of the sewage flow of the pipe network of the sewage plant during a certain period of time, and also plan for the investigation of the water flow of the other river basin pipeline network, and do a good job in the next inter-basin water allocation Ready to work.
The flow monitoring test is divided into two parts, one is to strictly follow the use requirements of the flow sensor, use the fixing ring to fix the area/rate sensor at the standard position of the bottom of the pipe, so as to check the accuracy of the flow monitoring; the second is to use the flow sensor 'Lead fish' device to quickly detect the sewage flow in the pipeline.