Exp. No 6 Static and dynamic pressure.pdf

This is a lab report about finding the static and dynamic pressure

1. 1



Experiment No. (6)
Static and Dynamic pressure
Petroleum Engineering Department
Faculty of Engineering
Koya University

Experiment date:
28/11/2023
Submission date:
5/12/2023


Prepared by:
1-Kaiwan B. HamaSalih 2- Rebin F. Hussien
Supervised by:
Dr. Jaffar A. Ali Mr. Nawrasi


Fluid Mechanics Lab
Lab Report

2. 2

Summary
In this experiment our goal was to find the dynamic pressure in a moving fluid using
piezometer and pitot tube. By calculating its static pressure and its total pressure, and finding
the dynamic pressure.

3. 3

Table of Content







Subject Pages
Introduction……………………………………......…………………………… …………… 4
Aim/Objective of Experiment…….........……………………………………… …………… 4
Theory of the experiment…………………………………………………………………… 5
Table of Reading.…………………...……………………………………… ………………. 6
Sample of Calculation....…………...……………………………………… ………………. 7-9
Table of Calculation………………...……………………………………… ………………. 10
Result………………………………………………………………………… ……………... 11
Discussion (Kaiwan B. HamaSalih) ....………………………………… …………………... 12-14
Discussion (Rebin F. Hussien)……………………………………………………………… 15
Conclusion………………………....………………………………………… ……………... 16
Reference………………………....………………………………………… ………………. 17

4. 4

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.

Guilherme Caminha (November 9
th
, 2023) Static and dynamic pressure are important concepts
in fluid mechanics and aerodynamics. Guilherme Caminha (November 9
th
, 2023) Static
pressure refers to the pressure exerted by a fluid at rest, also known as hydrostatic pressure [1].
Guilherme Caminha (November 9
th
, 2023) It is the pressure that occurs inside liquids and is
exerted by the weight of the liquid itself [1]. L.J. Clancy (1975) On the other hand, dynamic
pressure, also known as velocity pressure, is a result of the velocity of a fluid inside a pipe [2].
Hina Adeel (4/1/2022) It can be defined as the rate of an increase in density of a fluid due to
its motion [3]. Guilherme Caminha (November 9
th
, 2023) The formula for static pressure is
P=
F
A
, where P is the pressure, F is the force exerted by the liquid, and A is the area over which
the force is exerted [1]. L.J. Clancy (1975) The formula for dynamic pressure isq=
1
2
ρ.u
2
,
where q is the dynamic pressure, ?????? is the density of the gas, and u is the velocity in the direction
of flow [2]. Guilherme Caminha (November 9
th
, 2023) Static pressure is measured through
various methods, including pressure transducers and tapping in the side of a duct [1]. Tom
Weideman (No date) Dynamic pressure is often assigned the letter q in aerodynamics and is
used in various applications such as aerodynamics and fluid dynamics [4].
Aim/Objective of Experiment
 Finding the dynamic pressure.
 The aim of this experiment is to find the dynamic pressure in a moving fluid using
piezometer and pitot tube. By calculating its static pressure and its total pressure.

5. 5

Theory of the experiment:

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:
??????
�??????�.=
1
2
??????.??????
2
………………. Eq. (1)
The dynamic pressure thus rises with the square of the flow speed. The total pressure Pt in
the pressure tube is the sum of the static and dynamic pressure:
??????
�=??????
�+??????
�??????�. ………………………Eq. (2)
Since the two measurements are measurements of gauge pressure (i.e., the atmospheric
pressure Patm. =0) (upper vent valve open), the static pressure PS can be read from the
piezometer and the total pressure Pt from the pitot tube. The pressures read (1cmHOW ≈
1mbar) produce the flow velocity of the water as:
??????=√
2??????
??????????????????.
??????
………………………Eq. (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.

6. 6

Experimental Work:
Table of Readings
No. ??????
�
??????
(????????????)
??????
�
??????
(????????????)
1 2.8 15
2 6.5 19
3 9.5 23.5
4 18.7 35








0
5
10
15
20
25
30
35
40
Pt/
??????
(
�
�
)
Ps/??????(��)
Cuvre ????????????/??????and ??????t/??????

7. 7

Sample of Calculation
1.
??????
??????????????????.
??????
=
??????�
??????
−
??????�
??????
in (cm)
2. ??????=√
2??????
??????????????????.
??????
in (
��
�
)
No. (1):
Given/
??????
�
??????
=15 ????????????
??????
�
??????
=2.8
Unknown/
??????
??????????????????.
??????
=?
Solution:
??????
??????????????????.
??????
=
??????�
??????
−
??????�
??????

??????
??????????????????.
??????
=15−2.8
??????
??????????????????.
??????
=12.2 ????????????
??????=√
2??????
??????????????????.
??????

??????=√2??????ℎ
??????=√2×981×12.2
??????=154.7 (cm/s)

8. 8


No. (2):
Given/
??????
�
??????
=19 ????????????
??????
�
??????
=6.5 cm
Unknown/
??????
??????????????????.
??????
=?
Solution:
??????
??????????????????.
??????
=
??????�
??????
−
??????�
??????

??????
??????????????????.
??????
=19−6.5
??????
??????????????????.
??????
=12.5 ????????????
??????=√
2??????
??????????????????.
??????

??????=√2??????ℎ
??????=√2×981×12.5
??????=156.6 (cm/s)
No. (3):
Given/
??????
�
??????
=23.5 ????????????
??????
�
??????
=9.5 cm
Unknown/
??????
??????????????????.
??????
=?
Solution:
??????
??????????????????.
??????
=
??????�
??????
−
??????�
??????

??????
??????????????????.
??????
=23.5−9.5
??????
??????????????????.
??????
=14 ????????????

9. 9

??????=√
2??????
??????????????????.
??????

??????=√2??????ℎ
??????=√2×981×14
??????=165.7 (cm/s)
No. (4):
Given/
??????
�
??????
=35 ????????????
??????
�
??????
=18.7 cm
Unknown/
??????
??????????????????.
??????
=?
Solution:
??????
??????????????????.
??????
=
??????�
??????
−
??????�
??????

??????
??????????????????.
??????
=35−18.7
??????
??????????????????.
??????
=16.3 ????????????
??????=√
2??????
??????????????????.
??????

??????=√2??????ℎ
??????=√2×981×16.3
??????=178.8 (cm/s)

10. 10

Table of Calculation
No. ??????
�??????�.
??????
(????????????)
V (cm/s)
1 12.2 154.7
2 12.5 156.6
3 14 165.7
4 16.3 178.8









0
20
40
60
80
100
120
140
160
180
200
??????
(
�
??????
�
.
)/
??????
(
�
�
)
Velocity (cm/s)
Cuvre between ??????(�??????�.)/??????and Velocity

11. 11

Results:
 We knew how to Measuring the fluid flow rate.
 We knew how to define the errors and how to fix it if it was possible.

12. 12

Discussion-Kaiwan B. HamaSalih
1. Draw
??????
�
??????
,
??????
�
??????
&
??????
??????????????????.
??????
with the velocity of flow then discuss them.

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.
2. How is static pressure related to potential energy, and how is dynamic pressure
related to kinetic energy?
Static pressure and dynamic pressure are two components of the total mechanical energy
of a fluid, which exists in two forms: potential and kinetic. Static pressure is the pressure
at a given point in the fluid, while dynamic pressure is the kinetic energy per unit volume
of a fluid particle. Dynamic pressure exists when there is bulk fluid motion creating a
kinetic energy component. The kinetic energy of the fluid is stored in static pressure and
dynamic pressure, where the latter can be thought of as the fluid's kinetic energy per unit
volume. Bernoulli's equation expresses the relationship between static pressure,
potential energy, kinetic energy, and friction losses. In Bernoulli's equation, the total
energy along a streamline is constant and is a balance between static and dynamic
pressure. Mathematically, this implies that if there is no change in potential energy along
a streamline, the total energy along that streamline is constant. Therefore, Bernoulli's
equation can be used to predict the pressure (head) anywhere in a system.

0
10
20
30
40
50
60
70
80
154.7 156.6 165.7 178.8
Pressure
-
heads (cm)
Velocity(cm/s)
Chart Title
??????dyn./??????
??????t/??????
????????????/??????

13. 13

3. What is the difference between static pressure, total pressure, 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. It decreases with
an increase in speed because of conservation law.
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.
4. How can the Prandtl's pitot tube be used to measure dynamic pressure in a fluid?
A Prandtl tube, also known as a pitot-static tube, is used to measure dynamic pressure
in a fluid. It consists of two concentric tubes, with the central one having an open end
pointing upstream of the fluid flow, and the other closed at the end but with small holes
drilled at right angles to the direction of flow. The central tube measures the stagnation
pressure of the fluid, which is the total pressure, while the outer tube measures the static
pressure. By using a U-tube filled with liquid, the pressure difference between the total
pressure and the static pressure can be measured, and this pressure difference is a
measure of the dynamic pressure or flow velocity. The Prandtl tube can be used to
determine the flow speed relative to the tube, making it a valuable tool for measuring
fluid flow velocity.
5. What is the relationship between flow rate and cross-sectional area?
The relationship between flow rate and cross-sectional area is that if the cross-sectional area
changes, then the velocity of the fluid must change to keep the flow rate constant. The fluid
speeds up when entering a narrower section and slows down when entering a wider segment
of the pipe.
6. How does the velocity of a fluid affect the static pressure at its surface?
The velocity of a fluid affects the static pressure at its surface through the principles of
fluid dynamics, particularly Bernoulli's equation. As the velocity of a fluid increases, the
static pressure at its surface decreases. This is due to the conservation of energy and
momentum in the fluid flow. According to Bernoulli's equation, the total pressure in a
fluid flow is the sum of the static pressure and the dynamic pressure, which is
proportional to the square of the fluid velocity. Therefore, as the fluid velocity increases,
the dynamic pressure increases, causing a decrease in static pressure to maintain the total
pressure constant.

14. 14

7. What are the factors that could effect on a fluids slow rate?
1. Viscosity of the fluid
2. Density of the fluid
3. Velocity of the fluid
4. Change in temperature that will Couse to change in viscosity and density
5. Physical properties of the pipe that the fluid goes throw i.e.
The length, inner dimeter.

15. 15

Discussion-Rebin F. Hussien
1. 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.
2. what happening to the total and dynamic and static pressure if the velocity
increases?
if the velocity increases ail of Dynamic, static and Total Pressure Increases but for
Dynamic pressure it increases with square of the Flow velocity.
3. 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.
4. What are 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 having 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 goes bad so here we have a problem while the
test because the machine gives us a wrong pressure because sensor is an important part
of the hydraulic pressure.

16. 16

Conclusion:
static pressure and dynamic pressure are two important concepts that help in understanding the
behaviors of fluids. Static pressure refers to the pressure exerted by a fluid when it is at rest or
moving at a constant velocity. It arises from the random motion and collisions of molecules
within a fluid, resulting in a force perpendicular to the surface. This pressure does not account
for the dynamic effects of fluid motion, such as changes in velocity or acceleration. On the
other hand, dynamic pressure represents the pressure exerted by a fluid due to its motion or
velocity. It is a function of the fluid velocity and density, and can be thought of as the fluid's
kinetic energy per unit volume. Unlike static pressure, dynamic pressure considers the impact
of fluid movement and is related to the kinetic energy component created by bulk fluid motion.
The relationship between these pressures can be summarized as follows: Total Pressure
(Stagnation Pressure) = Static Pressure + Dynamic Pressure. When the fluid is stationary, the
static pressure is measured, while the dynamic pressure exists when there is bulk fluid motion
creating a kinetic energy component. Understanding these concepts is crucial in engineering
applications to ensure proper fluid flow, structural integrity, and system performance. They are
used to analyze and design fluid systems effectively, and are essential in the application of
Bernoulli's principle as an energy balance on a closed system.

17. 17

Reference:
1. Guilherme Caminha (November 9
th
, 2023), Fluid Dynamic: What is static pressure? ,
Available at https://www.simscale.com , Accessed at 24/11/2023.
2. L.J. Clancy (1975), Aerodynamics, Pitman Publishing Limited, London, Available at
https://en.wikipedia.org , Accessed at 24/11/2023.
3. Hina Adeel (4/1/2022), What is Dynamic pressure, Available at https://study.com ,
Accessed at 24/11/2023.
4. Tom Weideman (No date), Static Fluids, Available at https://phys.libretexts.org ,
Accessed at 24/11/2023.s