Petroleum engineering department at Koya University Fluid Mechanics laboratory 2020

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Faculty of Engineering Petroleum
Engineering Department
Fluid Mechanics Laboratory, 2nd stage
Experiment Name. Static and Dynamic pressure
Prepared by: Muhammed Fuad Rashid
Ahmad Jalal Hasan
Muhammad Hasan Aziz
Safwan Tofiq
Group: A
Supervised by: Mr. Dara & Mr. Younis

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Contents
1.0 Aim of experiment: .........................................................................................................................................................3
2.0. Introduction...................................................................................................................................................................4
3.0. Theory............................................................................................................................................................................5
4.0. Procedures.....................................................................................................................................................................6
4.1. Preparing the experiment...........................................................................................................................................7
5.0. Tools used in the experiment .........................................................................................................................................8
6.0. Discussion ......................................................................................................................................................................9
7.0. References:..................................................................................................................................................................13

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1.0 Aim of experiment:
Finding the dynamic pressure.

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2.0. Introduction
Two different pressures occur in flowing liquids:
-Static pressure: pressure acting transverse to the
direction of flow, which can be measured with a
piezometer.
-Dynamic pressure: pressure acting in the
direction of flow, which can be measured with a
piezometer and a pitot tube.
As the flow speed increases the dynamic pressure
rises and the static pressure falls. In a still liquid the
dynamic pressure is zero and the static pressure is
equal to the hydrostatic pressure.

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3.0. Theory
The piezometer with the pitot tube arrangement is called Prandtl’s tube. The difference between the
indicated pressures is the dynamic pressure of the water flowing through the pipe system.
The dynamic pressure Pdyn. is the pressure required to set the
medium in motion. It depends on the density of the flowing
medium. and its speed, V :
2
.
2
1
VPdyn 
…………….(1)
The dynamic pressure thus rises with the square of the
flow speed.The total pressure tP
in the pressure tube is the
sum of the static and dynamic pressure:
.dynst PPP 
……….….(2)
Since the two measurements are measurements of gauge pressure(i.e the atmospheric pressure
Patm.=0) (upper vent valve open ), the static pressure SP
can be read from the piezometer and the
total pressure tP
from the pitot tube.
The pressures read (1cmHOW ≈ 1mbar) produce the flow velocity of the water as:

.2 dynP
V 
…………….(3)
The Prandtl’s tube is primarily used in engineering to measure the speed of gases, to determine the
speed of an aircraft in flight for example.

dynP

tP

SP

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4.0. Procedures
1- Carefully open the upper vent valve and inlet cock, observing the water level: No water
should emerge from the
upper vent valve.
.sand PtRead of the two heads of water P-2
3- High pressures can be adjusted by means

SP

tP
of the inlet. If lower pressures are to be
measured, reduce the inlet cock and adjust
the head of water with the drain cock.

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4.1. Preparing the experiment
Before the actual measurement the manometer
must be prepared and vented:
* Connect the outputs of the Prandtl’s tube (11) by theconnecting
hoses to the dual water manometer (10).
* Close all cocks of the pipe system, and the vent valveson the water
manometer.
* Switch on the pump and open the pipe system inlet cock.
* Open the lower vent valves of the water manometer:
The pipe section and connecting hoses are vented by the waterflow.
When there are no more air bubbles in the connecting hoses, close the lower
vent valves simultaneously, then close the inlet cock and open the drain
cock.

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5.0. Tools used in the experiment

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6.0. Discussion
1 Draw
,

tP

SP
& 
.dynP
with the velocity of flow then discuss them.
:By Muhammed Fuad RashidAnswers
.Q1
As shown in the chart velocity will increase with increasing all static, dynamic and total pressure.
The effect of static pressure to velocity is greater than dynamic and total pressure, and the effect
of total pressure is greater than dynamic pressure.
Q3. What is the errors in this experiment?
Most of experiments and tutorially tests have their special errors and in this test which is about
hydraulic, dynamic pressure surely have some errors which are:-
Using an impure water for the test.
Have a mistake via reading the pressure in digital pressure supply.
Sometimes the sensor go bad so here we have a problem while the test because the machine
give us a wrong pressure because sensor is an important part of the hydraulic pressure.
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V
P
P dyn
Ps
Pt

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Answers by Muhammad Hassan Aziz
Q1.
Q2.What does dynamic pressure mean?
Dynamic pressure (sometimes called velocity pressure) is the increase in a moving
fluid's pressure over its static value due to motion.
what happening to the total and dynamic and static pressure if the velocity increases ?
if the velocity increases all of Dynamic,static and Total Pressure Increases but for Dynamic
pressure it increases with square of the Flow velocity .
Q3. What is the difference between static and dynamic pressure?
Static pressure is the pressure you have if the fluid isn't moving or if you are moving with the
fluid. Air would press against you equally in all directions. ... Dynamic pressure is the pressure of
a fluid that results from its motion. It is the difference between the total pressure and static
pressure
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Answers by Safwan Tofiq
Q1.
In the figure above, it appears that the relation from all cases is directly proportional, in but there
are differences in the amount in the cases, velocity greater changes with static pressure than
dynamic and total pressure. And it will change lower with dynamic pressure than the static and
total pressure.
What is the difference between static pressure, total (ram) pressure, and
dynamic pressure?
1. Pressure is the continuous physical force exerted on or against an object by
something (a fluid such as air) in contact with it. Static pressure is the pressure
you have if the fluid isn't moving or if you are moving with the fluid. Air would
press against you equally in all directions. It decreases with an increase in speed
because of conservation law. Total (or ram) pressure is the pressure a fluid
exerts as it is brought to a stop. Total pressure is what acts on you as you face
into the wind and the air collides with your body. Dynamic pressure is the
pressure of a fluid that results from its motion. It is the difference between the
total pressure and static pressure. Pilots rely on instruments that measure
dynamic pressure to determine their airspeed.
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Dicussion by ahmad jalal hasan
1-Draw
,

tP

SP
& 
.dynP
with the velocity of flow then discuss them.
As we can see here on this plot ,with increasing of head of the static fluid also the dynamic
head of the fluid increases ,and vise versa also as increasing of the dynamic movement of the
fluid it makes its velocity larger, this is due to the equation of dynamic include to find velocity
which is proportional to its velocity .
2-What is the difference between dynamic pressure and static pressure?
Static pressure is the pressure you have if the fluid isn't moving or if you are moving with the
fluid. Air would press against you equally in all directions. ... Dynamic pressure is the pressure of
a fluid that results from its motion. It is the difference between the total pressure and static
pressure.
3-What is meant by dynamic pressure?
Dynamic pressure is the kinetic energy per unit volume of a fluid particle. Dynamic pressure is in
fact one of the terms of Bernoulli's equation, which can be derived from the conservation of
energy for a fluid in motion.
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4-How do you calculate dynamic wind pressure?
Wind pressure is given by the equation P = 0.00256 x V2, where V is the speed of the wind in
miles per hour (mph). The unit for wind pressure is pounds per square foot (psf). For example, if
the wind speed is 70 mph, the wind pressure is 0.00256 x 702 = 12.5 psf.
5-When h(static) equals to h(hdynamic)
This phenomemn happins in the appartues tube scale when the two surface of the liquid are on
same line by another mean they have the same head.the two head can be more equal and precise
With increasing flow rate of the water this will make the ogyjin inside the two valves to persave
and spread in the two valves more equaly , but all things happin if the valve above the liquid
should be closed to atmospheric(NOT OPEN).
7.0. References:
1. Sentence.yourdictionary.com. (2019). Use meas in a sentence | meas sentence examples. [online] Available at:
https://sentence.yourdictionary.com/meas [Accessed 11 Nov. 2019].
2. Anon, (2019). [online] Available at: https://www.researchgate.net/scientific-contributions/2001672838_Otis_R_Walton
[Accessed 11 Nov. 2019].
3. Answersdrive.com. (2019). What is static fluid pressure? | AnswersDrive. [online] Available at:
https://answersdrive.com/what-is-static-fluid-pressure-1630632 [Accessed 11 Nov. 2019].

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