Pitot Tubes Used to measure air speed on

Pitot Tubes • Used to measure air speed on airplanes • Can connect a differential pressure transducer to directly measure V 2/2 g • Can be used to measure the flow of water in pipelines Point measurement!

Pitot Tube 2 V 1 =V V 1 = 0 z 1 = z 2 Connect two ports to differential pressure transducer. Make sure Pitot tube is completely filled with the fluid that is being measured. Solve for velocity as function of pressure difference

Ping Pong Ball Why does the ping pong ball try to return to the center of the jet? What forces are acting on the ball when it is not centered on the jet? How does the ball choose the distance above the source of the jet?

Jet Problem • How could you choose your elevation datum to help simplify the problem? • How can you pick 2 locations where you know enough of the parameters to actually find the velocity? • You have one equation (so one unknown!)

Jet Example The 2 cm diameter jet is 5 m lower than the surface of the z reservoir. What is the flow rate (Q)? Elevation datum 1 2 What about the free jet? V 2 = 9. 89 m/s Q = A V 2 = 3 E-3 m 3/s

Orifice and vena contracta We are to consider the flow from a tank through a hole in the side close to the base Looking at the streamlines you can see how they contract after the orifice to a minimum cross section where they all become parallel, at this point, the velocity and pressure are uniform across the jet. This convergence is called the vena contracta (from the Latin 'contracted vein'). It is necessary to know the amount of contraction to allow us to calculate the flow.

Orifice and vena contracta

Venturi , nozzle and orifice meters The Venturi, nozzle and orifice-meters are three similar types of devices for measuring discharge in a pipe.

A Venturi meter in laboratory

Venturi Meter

Venturi Meter Where, H

Venturi Meter This is also theoretical discharge in terms of manometer readings

Venturi Meter Example 1

Venturi Meter Example 1 where

PIPE ORIFICES ¢ A similar effect as the venturi meter can be achieved by inserting an orifice plate ¢ The orifice plate has an opening in it smaller than the internal pipe diameter