Fluid Mechanics Lab

Posted by : Asad Ali Arshad Wednesday, 21 February 2018

To determine the velocity of fluid flowing through the circular tube using a pitot tube
(Pitot Tube Apparatus)

What is a Pitot Tube?

ØA Pitot tube, also known as Pitot probe, is a pressure measurement instrument used to measure fluid flow velocity.The pitot tube was invented by the French engineer Henri Pitot in the early 18th century. It is widely used to determine the airspeed of an aircraft, water speed of a boat, and to measure liquid, air and gas flow velocities in certain industrial applications.

The pitot tube is used to measure the local flow velocity at a given point in the flow stream and not the average flow velocity in the pipe or conduit.

Working Operation:

uThe basic pitot tube consists of a tube pointing directly into the fluid flow. As this tube contains fluid, a pressure can be measured; the moving fluid is brought to rest (stagnates) as there is no outlet to allow flow to continue. This pressure is the stagnation pressure of the fluid, also known as the total pressure or (particularly in aviation) the pitot pressure.

uThe measured stagnation pressure cannot itself be used to determine the fluid flow velocity (airspeed in aviation). However, Bernoulli's equation states:

Stagnation pressure = static pressure + dynamic pressure

Apparatus: Pitot tube apparatus

Procedure:

1. Place the pitot tube apparatus on the hydraulic bench.

2. Attach the pitot tube with hydraulic bench using pipe and quick release connectors.

3. Start the pump, and admit water to the tube by opening the flow control valve. adjust the flow rate in the tube using the flow control valve of apparatus and hydraulic bench simultaneously so that there are no air bubbles within the tube.

4. Change the flow rate and get different values.

5. For each flow rate allow conditions to become steady, measure and record h1 (static head) and h2 (stagnation head).