Instantaneous Velocity Profile Measurement by Ultrasonic Doppler Method

Abstract

The Ultrasonic Velocity Profile (UVP) measuring method has been developed at PSI. It utilizes pulsed ultrasonic echography together with the detection of the instantaneous Doppler shift frequency. This method mainly has the following advantages over the conventional techniques : 1) an efficient flow mapping process, 2) applicability to opaque liquids and 3) a record of the spatiotemporal velocity field. After a brief introduction of its principle, the characteristics and specifications of the present system are given. Then examples such as for oscillating pipe flow, T-branching flow of mercury and circular free jet flow in fluid engineering are described, which confirm the above advantages. In a further in-depth study of fluid dynamics, results of an investigation of modulated wavy flows in a rotating Couette system are presented. The position-dependent power spectrum and time-dependent energy spectral density were used in order to study the dynamic characteristics of the flow, and subsequently the velocity field was decomposed into intrinsic wave structure based on the two-dimensional Fourier analysis.