PHASE MODULATION OF THE ULTRASONIC WAVE IN VON KARMAN STREET
Mustafa Music
Abstract:
It is known that under certain conditions (in certain Reynolds number region) we get double row of staggered vortices in fluid flow behind the bluff body. Frequency of generated vortices is directly proportional to the average velocity of fluid and that dependence is linear. Flowmeters based on this phenomenon are known as vortex flowmeters. Origination of vortices causes changes some other parameters such as: pressure, perpendicular forces on fluid flow, etc. Frequency of vortices can be detected by detecting changes of these parameters. Great majority of the vortex flow meters are functioning using this principle. Mathematical model of the phase modulation of ultrasonic wave that is transmitted normally on the fluid flow behind the bluff body in the region of stable flow will be given in this paper. Phase modulation is directly caused by appearance of vortices in the fluid flow. We have developed the prototype of ultrasonic vortex flow meter (PVMP 100) DN 100 based on phase ultrasonic modulation, for liquid flow measurement. Experimental results of testing this prototype vortex meter will be presented in this paper.
