PHY13 Ultrasonic Doppler Effect

Ultrasonic Doppler Effect Introduction to the basics of flow measurement based on the acoustic or ultrasonic Doppler effect The experiment introduces the basics of flow measurement based on the acoustic or ultrasonic Doppler effect and investigates its dependence on flow velocity and Doppler angle. Keywords: frequency shift, scattering, Doppler effect, Doppler sonography, flow measurement The Doppler effect is the change in the perceived frequency of waves while the transmitter and receiver are moving relative to each other. This effect is used to image moving structures. For example, the flow velocity or flow rate of a liquid stream can be determined using ultrasound. The frequency shift of an ultrasonic wave that is coupled into the liquid stream at a certain Doppler angle is measured when the wave is scattered by small particles, such as contaminants. In the experiment, the dependence of the Doppler frequency shift Δf on the flow velocity v (movement speed of the scattered particles) and the Doppler angle α for different fundamental frequencies f 0 is investigated by varying the pump power, the transmission frequency and the angle of incidence. The following simplified relationship applies to a pulse-echo system with an ultrasonic transducer: Δf ~ f 0 v cos(α). The graphics show the frequency shift and the ratio Δf / cos(α) as a function of the pump power for different Doppler angles at the transmission frequency of 2 MHz. The determined Doppler frequency shift increases with increasing speed and decreasing Doppler angle. The quotient Δf / cos(α) (the flow velocity v) is constant for the same pump power, ie no angle-dependent measurement errors occur.   Screenshot of the FlowView measurement software Deoppler frequency shift depending on pump speed and Doppler angle Flow velocity depending on pump speed SCOPE OF DELIVERY: Item No. Designation 50400 Ultrasound Doppler FlowDop200 10151 Ultrasonic probe 1 MHz 10152 Ultrasonic probe 2 MHz 10154 Ultrasonic probe 4 MHz 50130 Centrifugal pump MultiFlow 50140 Doppler fluid 50201 Flow set 70200 Ultrasound gel   ADDITIONAL EXPERIMENTS: PHY15 Flow laws MED03 Basics of Doppler sonography MED05 Vascular diagnostics with ultrasound (angiology) MED06 Blood pressure measurement with ultrasound (Doppler occlusion pressure measurement)