This document describes an experiment measuring center of pressure and hydrostatic force using a hydrostatic pressure system. Known masses were added to one end of the apparatus and water was added until the arm balanced, recording the water height. This process was repeated for partially and fully submerged surfaces. For partially submerged surfaces, center of pressure decreased linearly with water height while hydrostatic force increased as a power function. For fully submerged surfaces, center of pressure decreased as a power function of water height and hydrostatic force increased linearly. The experiment confirmed theoretical relationships between these variables and the water height.

1. 1
Center of Pressure
Student Name: Rawa Abdullah Taha
Class: two – Group A
Course Title: Fluid Mechanics Lab
Department: Mechanic and Mechatronics
College of Engineering
Salahaddin University - Erbil
Academic Year 2019 – 2020

2. 2
ABSTRACT
Hydrostatic Pressure Systems agree for the measurement and
development of hydrostatic force and center of pressure equations and
values essential to build and evaluate fluid systems. To demonstrate this
capability, known masses were added to one end of an Edibon
Hydrostatic Pressure System, and water was added into the system until
the arm was level (balancing the moment about the pivot). The
conforming height of the water was recorded and used to calculate the
center of pressure and hydrostatic force on the vertical rectangular
quadrant. These values were plotted against the height of the water. This
process was repeated for both partially and fully submerged surfaces. For
the partially submerged surface, the center of pressure had a linear
relationship with the height of the water, while there was a power
relationship between these variables for a fully submerged surface. For
the partially submerged surface, hydrostatic force had a power
relationship with the height of the water, and, for a fully submerged
surface, hydrostatic force had a linear relationship with the height of the
water.

3. 3
TABLE OF CONTENTS
Abstract 2
Table of Contents 3
Introduction 4
Introduction 5
Methods 6
Conclusion 7
References 8

4. 4
INTRODUCTION
Several engineering assemblies such as, flood control gates and fluid
storage tanks , dams ,are indispensable components of large hydraulic
structures. Many of these structures are constructed to provide water
supply and irrigation and they play an important role in maintaining the
well-being of mankind. The design of these components requires the
understanding of how fluid forces act. Such designs require not only
resolve of the magnitude of the resultant force but also its point of action,
which is known as the (center of pressure). With this information,
engineers can design the hydraulic structure to withstand the hydrostatic
forces.
Figure(1)
Hydrostatic Press Systems allow for the measurement and growth of
hydrostatic force and center of pressure equations and values necessary to
build and gauge fluid systems. To validate this capability, known masses
were added to one end of the center of pressure apparatus, and water was
added into the system until the arm was level (balancing the moment
about the pivot). The corresponding height of the water was recorded and
used to calculate the center of pressure and hydrostatic force on the
vertical rectangular quadrant. These values were planned against the
height of the water. This process was repeated for both partially and fully

5. 5
submerged surfaces. For the partially flooded surface, the center of
pressure had a linear connection with the height of the water, while there
was a power relationship between these flexible for a fully submerged
surface. For the partially submerged surface, hydrostatic force had a
power relationship with the height of the water, and, for a fully
submerged surface, hydrostatic force had a linear relationship with the
height of the water. Thus, in both cases, the data collected verified the
relationships of center of pressure and hydrostatic force against height
presented in the given equations. Because the moment about the pivot
must be zero, the relationship between mass and height further confirmed
these findings. In order to assess the accuracy of the measurements taken
by the pressure system, the theoretical heights were compared to the
experimental values of height. Because the slope of this relationship was
nearly one, the accuracy of the pressure system was confirmed, and no
calibration was needed. The plot of standard deviation between
theoretical and measured height against measured height supports this
result.
Figure(2)

6. 6
METHODS
stable shape is desirable in sailing and missiles etc., but
in aircraft design as well. Aircraft design therefore borrowed the term
center of pressure. And like a sail, a rigid non-symmetrical airfoil not
only produces lift, but a moment. The center of pressure of an aircraft is
the point where all of the aerodynamic pressure field may be represented
by a single force vector with no moment. A similar idea is
the aerodynamic center which is the point on an airfoil where the pitching
moment produced by the aerodynamic forces is constant with angle of
attack.
The aerodynamic center plays an important role in analysis of
the longitudinal static stability of all flying machines. It is desirable that
when the pitch angle and angle of attack of an aircraft are disturbed (by,
for example wind shear/vertical gust) that the aircraft returns to its
original trimmed pitch angle and angle of attack without a pilot
or autopilot changing the control surface deflection. For an aircraft to
return towards its trimmed attitude, without input from a pilot or
autopilot, it must have positive longitudinal static stability.
Figure(3):Aerodynamic Center

7. 7
CONCLUSION
In my report I explained generally about the center of pressure in
mechanics fluid lab I write the definition for it with images for better to
understand to remember The Hydrostatics Pressure System exactly
measures the height of the water in the chamber needed to calculate
both hydrostatic force acting on the vertical rectangular quadrant and
the center of pressure at which this force acts, with a low standard
eccentricity from the theoretical water height for both partially and fully
submerged surfaces. This is confirmed by the linear plots of theoretical
versus measured water height in which the slope is approximately one
for both the partially and fully submerged surfaces. The data gathered
from the pressure system also supports the relationships between
variables as they are presented in the equations given to calculate
hydrostatic force, center of pressure, and mass. In other words, the
hydrostatic force acting on both partially and fully submerged vertical
rectangular surface increases as the height of the fluid (water) in the
chamber increases. This relationship is supported by the plots of mass
versus theoretical height when the balance of the moments about the
pivot is considered. For both partially and fully submerged surfaces, the
center of pressure (measured from the balance bridge arm down)
decreases towards the centroid of the quadrant as the height of water in
the chamber increases.

8. 8
REFERENCES
[1]. Çengel, Y. A., & Cimbala, J. M. (2014). In Fluid mechanics:
Fundamentals and Applications (3rd ed., pp. 38-59). New York, NY:
McGraw-Hill Higher Education.
[2] Tadmor, R., & Yadav, P. S. (2007). As-Placed Contact Angles for
Sessile Drops. Journal of Colloid and Interface Science, 317(1), 241-246.
[3] Benson, Tom (2006)."Aerodynamic center(ac)". The Beginner's
Guide to Aeronautics. NASA Glenn Research Center. Retrieved 2006-04-
01
[4] Anderson, John D., Jr. (John David), 1937- (12 February
2010). Fundamentals of aerodynamics (Fifth ed.). New York.