#PitotTube #SolvedProblems #Bernoulli'sTheorem&continuityequation
The flowmeters are developed based on the principle of continuity equation and Bernoulli's theorem. These flow meters are also called differential flowmeters because for the computation of discharge, the only measurement one must conduct in the field is the measurement of differential pressure head. Pitot tube is used to measure the velocity of the stream. It is a glass tube bent at right angles and open at both ends. The tube is inserted into the flow, with horizontal open end facing the flow. The liquid enters and the liquid level in the vertical open end rises to the height h. When the pitot tube is used in open channels, h can be determined directly and can be utilized for the computation of velocity. Pitot tube can also be used to find out the velocity at any point in the pipes as well as in open channels. When the Pitot tube is inserted into the pipe which is running full. Within this pipe, the fluid particle is moving with flow velocity V. When it approaches and it touches the tip of the Pitot tube, the velocity of the fluid particle, that is equal to zero. The point at which the flow velocity, that is equal to 0, that is called as stagnation point and the pressure corresponds to the stagnation point is called as stagnation pressure. At this point, the velocity head, that is converted Pressure head. When Pitot tube is used in open channels, h can be determined directly because in open channels every point is subjected to Atmospheric pressure. So, h can be determined directly. But, when Pitot tube is to be used in pipe, the difference between the static pressure and the impact pressure at the hole must be determined with a differential pressure gauge using static pressure tapping in the pipe wall or we can connect one limb of this U tube manometer to the vertical open end of the Pitot tube and other end of this U tube manometer connected to the point to measure the static pressure. Due to the difference in pressure, a deflection in mercury level is observed and that to be converted to the differential pressure head by using pressure balance equation. Velocity can be calculated by measuring differential pressure head h. Discharge Q is calculated from continuity concepts.
V_ =√(2gh )
Q=a V
The tube, recording the static pressure and the stagnation pressure are frequently combined into one instrument, that is called Pitot Static tube. Here, Static tube surround the Pitot tube. So, the inner tube which is used to measure the impact pressure, whereas the annular tube, with holes on the surface which is used to measure the static pressure. The pressure transducer, can be used to determine the difference in static pressure and the impact pressure. So, the Pitot tube can be used to compute the discharge by calculating the velocity of the flowing fluid, by only measuring the differential pressure head. The solution of conceptual field problems based on continuity and Bernoulli’s equation are also discussed in this video.
Timestamps:
00:00 Introduction
00:55 Pitot tube
05:00 Measurement of Differential Pressure head
06:30 Pitot Static Tube
7:40 Problem 1
11:35 Problem 2
13:33 Problem 3
16:54 Problem 4

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