Biomedical Device Technology: Principles and Design
When the flowing fluid hits the wedge located at the center of the vessel, vortices are formed; these vortices create turbulence in the fluid, which can be detected by an ultrasound transmitter and receiver setup. The number of U/S transmitter Vortex
Fluid flow
Wedge U/S receiver
Figure 7–12. Ultrasound Vortex Flowmeter.
vortices formed is proportional to the velocity of the fluid.
Thermal Flowmeters A thermal flowmeter with a heating element and two temperature sensors (e.g., thermistors) placed at equal distance to the element is shown in Figure 7–13a. The heater heats the fluid in contact with the heating element. When there is no flow, the sensors are at the same temperature. The flow of the fluid causes a temperature imbalance. The flow rate as well as the direction of flow are determined by the temperature difference between the two Temperature sensors
