AIR FLOW VELOCITY MEASUREMENT

摘要

The proposed device for the air flow velocity measurement (the air flows inside a rectangular tube) is based on the pulse repetition rate method. Two oscillators which consist of a buffer stage, ultrasound transmitter and receiver and an amplifier, use a feedback downstream and upstream the air flow, respectively. A difference frequency is subsequently derived. To get higher measurement accuracy, the period is measured instead of the frequency. Personal computer (PC) controls the system, makes necessary calculations and displays the results.