Ultrasonic measurement of helium bubble rise and group velocity using 1-d and 2-d methods in water and mercury

Single element ultrasonic Doppler velocimeter flow measurement instruments are available (Metflow) that allow velocity measurement along the main lobe of the transducer through gated processing of Doppler shift from echoes from targets in the flow. Correlation of target migration through the time gates has been used to supplement the Doppler data, and to measure void wave speeds when the targets are bubbles in the liquid flow. These methods are developed using helium bubbles in water flow with optical verification, and then used with helium bubbles in mercury. A second method for bubble rise velocity is presented using conventional 2-D medical ultrasound imaging equipment by Terason, with a 12L5V transducer, to develop an ultrasonic imaging analogue to conventional Particle Image Velocimetry. This system is also first tested in the water with helium bubbles using optical verification, and then in the mercury with helium bubbles.