The rotor rotation is approximately proportional to

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s can also be used in unconfined flow situations, such as winds or ocean currents. They can be compact, even microsize with two or three component directions. Figure 6.32 illustrates a handheld wind velocity meter which uses a sevenbladed turbine with a calibrated digital output. The accuracy of this device is quoted at 2 percent. Vortex flowmeters. Recall from Fig. 5.2 that a bluff body placed in a uniform crossflow sheds alternating vortices at a nearly uniform Strouhal number St fL/U, where U is the approach velocity and L is a characteristic body width. Since L and St are constant, this means that the shedding frequency is proportional to velocity f (const)(U ) (6.120) The vortex meter introduces a shedding element across a pipe flow and picks up the shedding frequency downstream with a pressure, ultrasonic, or heat-transfer type of sensor. A typical design is shown in Fig. 6.33. The advantages of a vortex meter are as follows: 1. 2. 3. 4. 5. Absence of moving parts Accuracy to 1 percent over a wide...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online