ABSTRACT In this experiment, is using the Armfield C6-MKII-10 Fluid Friction Apparatus. Normally, it will consider the frictional losses. It is occur because of the fluid viscosity and the formation of turbulence that caused the flow disturbances. The objective of this experiment is to determine the head loss due to fluid friction and velocity of flow water through the smooth bore pipes. After that, confirm the head loss friction factor which is f . Then, the data was recorded and the graph also was plotted. But the graph should get in proportional to each other. In addition, there are few factors in affecting the head loss which are flow rate, inner diameter of the pipe, roughness of the pipe wall, corrosion and scale deposits, viscosity of the liquid, fittings and also straightness of the pipe. There are existence of both human errors, parallax errors and environmental effect but there are always error counters to be taken place to increase the accuracy of the results.
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2.0
INTRODUCTION
The Fluid Friction Measurements Apparatus (Model: FM 100) has been planned to study on the fluid friction head losses of an incompressible fluid flow. After that, it studies the friction losses on smooth-bore pipes of various diameters and an artificially roughened pipe. Besides, to the study of losses in straight pipes, a wide range of accessories are also provided including 90° bend, elbow and T, 45° elbow and Y, sudden enlargement and contraction, inline strainer, various valves and flow meters.
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OBJECTIVES
In this experiment is to determine the relationship between head loss due to fluid friction and velocity for flow of water through smooth bore pipes and to confirm the head loss friction factor f. But at the same time, this experiment also was to compare the head loss that obtained by a pipe friction equation with the direct measure head loss .
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THEORY
The investigation on friction head losses in various straight pipes can be finish over a range of Reynolds numbers from 103 to nearly 105, control the laminar, transitional and turbulent flow in smooth pipe. An unnaturally roughened pipe is supplied which, at the higher Reynolds number, displays a clear departure from the typical smooth bore pipe characteristics. In addition, for each size of test pipe, a short sample is given loose so that students will be able to determine the exact diameter and imagine the nature of the internal finish. The ratio of the pipe diameter to distance of the pressure tapping from the ends of each pipe has been selected to reduce end entry effects. Next, isolating valves are provided so that the pipe to be tested can be selected without any failure or draining the system. Tests on parallel pipe configuration can be done whether rapid and accurate flow measurement is possible over the full working range of the apparatus.
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Basic theoretical background Two types of flow may exist in a pipe. 1) Laminar flow at low velocities where h ∝u 2) Turbulent flow at higher velocities where n h ∝u
Figure 1: height versus mean velocity
Where h is the head loss due to friction and u is the fluid velocity: For a circular pipe flowing full, the head loss due to friction may be calculated from the formula:
(1)
Where: L is the length of the pipe between tapings, d is the internal diameter of the pipe. U is the mean velocity of water through the pipe in (m/s). g is acceleration due to gravity in (m/s 2) f is the pipe friction coefficient
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The mean velocity, u is obtained from:
(2)
Where: Q is the volumetric flowrate (m 3/s) d is the diameter of pipe (m)
Reynolds' number, Re, is defined as:
(3)
Where: μ is the dynamic viscocity (1.15 Χ 10 -3 Ns/m2 at 15°C) p is the density (999kg/m 3 at 15°C)
The value of f may be determined as a function of Re and the relative roughness ε=e/d using a Moody diagram
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Figure 2: Friction factor f as a function of Reynolds number and relative roughness ( /D) For round pipes the Moody diagram.
Equation (1) can be used to determine the theoretical head loss by reading the value of f for the pipe in the Moody diagram if you know Re and ε . When h is measured experimentally, Equation (1) can be rearranged to compute an experimental value for f.
(4)
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APPARATUS
Main parts: • Smooth pipes of various sizes • Artificially roughened pipe • 90-degree mitre and elbow • 90-degree smooth bends (up to 150 mm radius) • Sudden enlargement • Sudden contraction • Gate valve, globe valve and ball valve • Venturi meter and orifice meter • Pitot static tube • In-line strainer • Test Pipes with inside diameters from 4 mm to 17 mm
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DIAGRAM C6-MKII-10 Fluid friction apparatus, H12-8 Hand held digital pressure meter, internal thermometer, stop watch and vernier caliper.
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6.0
PROCEDURE
1. Review apparatus description and set up procedure. 2. Prime the pipe network with water. Open and close the appropriate valves to obtain flow of water through the required test pipe. 3. Take readings at a number of different flow rates, altering the flow using the control valve on the apparatus. 4. To get a good head-flow curve, 10 readings is sufficient. 5. Measure flow rates using the volumetric tank. For small flow rates use the measuring cylinder. Measure head loss between the tapings using the portable pressure meter of pressurized water manometer as appropriate. 6.
Repeat the experiment for other smooth pipe.
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7.0
RESULTS
Table 1: The readings and results of the experiment. Volume
Time
Flow
, V (L)
,T
rate,
(sec)
(m3/s)
Q
Pipe
Velocity
Reynold
Measure
Friction
diameter
, u (m/s)
s
d
factor, f d
Number,
Loss, h
Loss, h
Re
(m H2o)
(m H2o)
, d (m)
Head
(hc – hD)
Calculate Head
Moody
diagra
m
The data above shows the result that was recorded and obtained to plot a graph of h versus u for each of size of pipe. There are three zones which is laminar, transition and turbulent zones that is determine from the graphs above. In addition, the result of graph was being compared between the theoretical and experimental curves.
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Graph 2: The fluid friction coefficient of a roughened pipe.
Graph 3: The head loss due to fittings
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8.0
DISCUSSION
In hydraulic engineering system, it is always needed to estimate the head loss incurred by a fluid as it flows along a pipeline. For instance, it may be desired to estimate the rate of flow along a proposed pipe connecting two reservoirs at different levels. Or it is necessary to calculate what additional head would be required to double the rate of flow along an existing pipeline. Loss of head is incurred by fluid mixing which occurs at fittings such as bends or valves, and by frictional resistance at the pipe wall. Where there are various fittings and the pipe is short, the major part of the head loss will be due to the local mixing near the fittings. For a long pipeline, otherwise, skin friction at the pipe wall wills most major. In the experiment described above, we investigate the frictional resistance to flow along a long straight pipe with smooth walls. Head loss is the decrease in the total head of a fluid which caused by the friction that exist in the fluid’s motion. Furthermore, friction loss occurs if the fluid flows through the straight pipes and minor losses are occur due to joints, valves, elbow, bend, and other equipment in the systems. So, when there are have a changes of the direction of flow then the cross-sectional area head loss also change. Basically, the pattern of this experiment is the head loss is directly proportional to the flow velocity whether for both laminar and turbulent phase but the transition phase is different. Next, in order to get the comparison between the theoretical graphs, the graph of experimental need to be constructed then the head loss was being calculated. Other than that, t he Reynolds’s number and Moody diagram is necessary to make the comparison between the experimental and theoretical curves.
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CONCLUSION
As conclusion, the fluid friction apparatus is planned to permit a detailed study of pressure drop due to fluid friction, head loss and show of heat in pipe when an incompressible fluid flows through pipes, equipment, and flow metering devices. Next, it also can be determining the friction head losses in straight pipes and fitting which by Darcy-Weisbach formula.
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10.0
RECOMMENDATION
In this experiment, we must ensure that the inlet of the hose is correctly inserted due to prevent water spray out. Next, we must wear necessary Personal Protective Equipment (PPE) which to prevent any harm occur. Then the most important is needed to remove air bubbles that trapped in a pipe before starting the experiment which give a better accuracy result.
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REFERENCES
a. Fluid Friction in Pipes and Fittings, http://www.selkagmbh.com/product_info.php?pName=fluid-friction-in-pipes-and-fittingsp-1287. Retrieved on 17 October 2013 b. Orifice Flow Meter Calculator, http://www.efunda.com/formulae/fluids/calc_orifice_flowmeter.cfm. Retrieved on 18 October 2013. c. Heat And Mass Transfer Fundamentals And Applications, A. Cengel and J. Ghajar, 4 th ed, (2011). d. Venturi Flow Meter Calculator, http://www.efunda.com/formulae/fluids/venturi_flowmeter.cfm. Retrieved on 18 October 2013 e. Types of Pipes, http://www.sandershomeservices.com/plumbing-types-of-pipes.php. Retrieved on 18 October 2013.
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APPENDICES
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