Steam flow measurement of a pipe flow such as factories and power stations is one of the significant techniques that enable us to diagnose and control the energy flow. The conventional flowmeter, however, needs the installation of the spool piece that disturbs the stable and continuous operation of the plants. In this study, the clamp-on ultrasound flowmeter has been developed by using focusing sensors. By the numerical simulation, the ultrasound propagation through steam and metal pipe was firstly investigated. The effects of the external damping material, applicable vapor pressure range as well as the appropriate shape of the acoustic lens were analyzed that was followed by the feasibility test of steam measurement system. Pressure and sensor dimension were varied to compare the efficiency of the ultrasound transmission between transducers. The signal processing algorithm was developed in order to discriminate the direct signal through the steam flow from the unwanted circumference noise through the solid stainless pipe. The linear relation between flow rate and ultrasound peak shift was confirmed.
