Flowmeters, velocity turbine

Velocity Meters Velocity meters measure fluid velocity. Examples include electromagnetic, propeller, turbine, ultrasonic Doppler, ultrasonic transit time, and vortex meters. Section 8 describes the principles of operation of electromagnetic, turbine, ultrasonic, and vortex flowmeters. 

Among the renewable energy processes, it is the wind turbines that benefit the most from the measurement of wind direction and velocity. Doppler-type sensors are used to determine the wind velocity and to obtain three-dimensional air motion profiles and also in the balancing of HVAC systems and measuring of the velocity of wet and dirty gases in industry. For a more detailed discussion of Pitot tubes and thermal flowmeters, also refer to the Sections 3.9.7.2 and 3.9.10. Here, the focus is on mechanical- and Doppler-type anemometers. 

The liquid turbine meter is one of the most accurate meters having the highest rangeability, and can handle practically any pressure and extremely high and low temperatures. Their capacities are listed in Table 3.92, and their installation is illustrated in Figure 3.93. Turbine flowmeters in gas service are similar but designed for higher velocity and lower torque. 

Fluid-power flowmeters are used in low-velocity, moderately viscous flows. In addition to industrial control applications, turbine flowmeters (Fig. 18.10(a)) are sometime used as speed indicators for ships or boats. Paddle wheel flowmeters (Fig. 18.10(b)) are used both in closed- and open-flow applications such as liquid flow in flumes. Since a fluid-power gear motor (Fig. 18.10(c)) is a constant volume device, motor shaft speed is always a direct indication of fluid flow rate. 

The turbine type volumetric flowmeter is a simple mechanism that consists of a freely rotating bladed rotor, supported by bearings inside a housing, and an electrical transducer that senses rotor speed (see Fig. 8.14). Rotor speed is a direct function of flow velocity or... 

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