INTRODUCTION Nowadays, a Pitot tube would be of use as a speedometer on aeroplanes. It is also found useful in industries where velocity measurements are required, where an anemometer may not be the most efficient instrument to use. There are three types of pitot tubes: Pitot tubes, Static tubes, and Pitot- Static tubes. The simple pitot tube essentially consists of a tube bent at - usually - 90°, with an open end pointing directly towards the fluid flow. As the fluid flows in the tube, it becomes stagnant since there is no direct opening at the other end for it to exit from. As the inert fluid rises, it creates a pressure of its own. This pressure is equivalent to the dynamic pressure, which can be seen as the kinetic energy ofthe fluid per unit weight. F.X. Pitot originally used this device to analyze the pressure created by the stagnating fluid at the other end of the tube. He did this by calculating the sum of the dynamic pressure and static pressure. The pressure created by the stagnant fluid (stagnation pressure) is found where the velocity component is zero. Using these principles, it is possible to determine a fluids velocity. This has manifested itself in the form of the Bernoulli equation. It describes this phenomenon as it states that an inviscid fluid’s increase in velocity is accompanied with a concurrent decrease in pressure or in the fluid's potential energy. However, this equation works on two assumptions – the first, that the fluid is incompressible; the second, that friction caused by viscous forces are to be considered negligible. The Bernoulli equation can nevertheless be used for compressible flows, but only at low Mach numbers. In the experiment, we measured the radial velocity profile at a cross-section of a pipe using the Pitot tube. As the Pitot probe is shifted along the pipe, we can record the stagnation pressure and static press ure at that cross-s ection of the pipe. The velocity of the inviscid fluid can now be found using both pressures. The smaller the diameter of the Pitot tube is, the more accurate the flow velocity. If the Pitot tube has too large a diameter, results for the fluid’s flow could be inaccurate due to the difference in velocity between the fluid against the tube walls and the fluid in the middle of the tube. 1
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Nowadays, a Pitot tube would be of use as a speedometer on aeroplanes. It is also found useful in
industries where velocity measurements are required, where an anemometer may not be the mostefficient instrument to use. There are three types of pitot tubes: Pitot tubes, Static tubes, and Pitot-
Static tubes.
The simple pitot tube essentially consists of a tube bent at - usually - 90°, with an open end pointing
directly towards the fluid flow. As the fluid flows in the tube, it becomes stagnant since there is no
direct opening at the other end for it to exit from. As the inert fluid rises, it creates a pressure of its
own. This pressure is equivalent to the dynamic pressure, which can be seen as the kinetic energy of
the fluid per unit weight.
F.X. Pitot originally used this device to analyze the pressure created by the stagnating fluid at
the other end of the tube. He did this by calculating the sum of the dynamic pressure and static pressure. The pressure created by the stagnant fluid (stagnation pressure) is found where the velocity
component is zero. Using these principles, it is possible to determine a fluids velocity.
This has manifested itself in the form of the Bernoulli equation. It describes this phenomenon
as it states that an inviscid fluid’s increase in velocity is accompanied with a concurrent decrease in
pressure or in the fluid's potential energy. However, this equation works on two assumptions – the
first, that the fluid is incompressible; the second, that friction caused by viscous forces are to be
considered negligible. The Bernoulli equation can nevertheless be used for compressible flows, but
only at low Mach numbers.
In the experiment, we measured the radial velocity profile at a cross-section of a pipe usingthe Pitot tube. As the Pitot probe is shifted along the pipe, we can record the stagnation pressure and
static pressure at that cross-section of the pipe. The velocity of the inviscid fluid can now be found
using both pressures.
The smaller the diameter of the Pitot tube is, the more accurate the flow velocity. If the Pitot
tube has too large a diameter, results for the fluid’s flow could be inaccurate due to the difference in
velocity between the fluid against the tube walls and the fluid in the middle of the tube.