A Model-Based Hybrid Ultrasonic Gas Flowmeter

Combining the transmission "Z" mode and the reflection "V" mode, a new hybrid dual-path ultrasonic sensor is designed to make full use of the advantages of the two modes. With the hybrid sensor and a new model-based timeof-flight (TOF) measurement method, a new model-based hybrid ultrasonic gas flowmeter is developed. The model-based TOF measurement method, which includes a signal filtering part and a model fitting part, is proposed to implement accurate TOF measurement. The signal filtering is implemented by a Butterworth bandpass filter and the model fitting is implemented by a hybrid Gauss-Newton structured BFGS method. A new hybrid ultrasonic flowmeter prototype with the inner diameter of 100 mm was developed and dynamic experiments were carried out. Experimental results show that the development of the hybrid ultrasonic flowmeter is successful. With the flowmeter prototype, the maximum relative error and the repeatability error of gas flowrate measurement are 1.80% and 0.45%, respectively, for a common flowrate ranges from 30 to 500 m(3)/h.