44 1.0 OBJECTIVES To determine the coefficient of discharge of given venturimeter. 2.0 EQUIPMENT Venturimeter, Differential Manometer, A Collecting Tank, Pizeometer, Stop Watch And Measuring Scale 3.0 MATERIALS & CONSUMABLES Water 4.0 INTRODUCTION Venturi meter is a flow measurement device, which is based on the principle of Bernoulli's equation. Inside the pipe pressure difference is created by reducing the cross-sectional area of the flow passage. This difference in pressure is measured with the help of manometer and helps in determining rate of fluid flow or other discharge from the pipe line. Venturi meter has a cylindrical entrance section, converging conical inlet, a cylindrical throat and a diverging recovery cone. Components of venturimeter: a) Cylindrical entrance section:This is the section having the size of a pipe to which it is attached. The venturi meter should be proceeded by a straight pipe of not less than 5 to 10 times the pipe diameter and free from fittings, misalignment and other source of large scale turbulence. b) Converging conical section:The converging takes place at an angle of 21±2°. The velocity of fluid increases as it passes through the converging section and correspondingly the static pressure falls. c) Throat:This is a cylindrical section of minimum area. The velocity is maximum and the pressure is minimum. The throat diameter is usually between ½ to ¼ of the inlet diameter. Length of the throat equals its diameter. d) Diverging section:This is a section in which there is a change of stream area back to the entrance area. The recovery of kinetic energy by its conversion to pressure energy is nearly complete and so the overall pressure loss is small. To accomplish a maximum recovery of kinetic energy the diffuser section is made with an included angle of 5° to 7°. This angle has to be kept less so that the flowing fluid has least tendency to separate out from the boundary of the section. VENTURI METER
45 Types of Venturi Tubes 1. a standard long-form or classic venturi tube 2. a modified short form where the outlet cone is shortened 3. an eccentric form to handle mixed phases or to minimize build-up of heavy materials 4. a rectangular form used in duct work Figure 1 : Types of Venturi Tubes The major disadvantages of this type of flow detection are the high initial costs for installation and difficulty in installation and inspection. The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The fluid velocity must increase through the constriction to satisfy the equation of continuity, while its pressure must decrease due to conservation of energy: the gain in kinetic energy is balanced by a drop in pressure or a pressure gradient force. An equation for the drop in pressure due to venturi effect may be derived from a combination of Bernoulli’s principle and the equation of continuity. Figure 2 : Meter Venturi Let d1 = Diameter at inlet or at section 1 V1 = velocity of fluid at section 1 P1 = Pressure at section 1 and d2, V2, a2 and P2 are the corresponding values at section 2. Applying Bernoullis equations at section 1 and section 2, we get,
46 Since the pipe is horizontal, so z1 = z2 Now applying continuity equation at section 1 and 2 Substituting value of v1 in equation (1.4) we get Where x = difference between the liquid column in U tube, But, discharge through venturimeter, Q=a2v2
47 Equation (1.5) gives the discharge under ideal conditions and is called as theoretical discharge. Actual discharge is given by, Actual discharge = Coefficient of venturimeter x Theoretical discharge 5.0 PROCEDURES 1. Scan QR Code below to access Simulation Lab. 2. Click Simulator to start Virtual Lab. 3. Open Venturi meter experiment, a window will appear as shown.
48 4. Select the required diameter of pipe, then click NEXT button. 5. Click on the main inlet valve to allow the flow through it. 6. Click on pipe inlet valve to allow the flow through it.
49 7. Click on manometer knot to change it from isolated position to air-vent position to remove air bubbles and again click to change it to read position. 8. Now click on tank outlet valve to open and allow flow, note the manometer reading. 9. Here the manometer reading is noted down. Calculate the value of Head Loss.
50 10. Fill in the value of Head Loss and then click CHECK 11. Click on tank outlet valve to close it to measure the discharge. The observation and calculations of the trial is given here.
51 12. Calculate actual discharge, theoretical discharge and coefficient of discharge. Repeat the same procedure for other trials. 13. Repeat the same procedure for other trials. 6.0 RESULT Table 1: 50 mm pipe inner diameter Pipe inner diameter (mm) 40 mm TRIAL 1 2 3 4 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Area of collecting tank (A) Time Taken (t) Rise (h) = Area 1 Area 2 = √ ( − ) = ℎ Average
52 Table 2: 40 mm pipe inner diameter Pipe inner diameter (mm) 40 mm TRIAL 1 2 3 4 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Area of collecting tank (A) Time Taken (t) Rise (h) = Area 1 Area 2 = √ ( − ) = ℎ Average Table 3: 20 mm pipe inner diameter Pipe inner diameter (mm) 20 mm TRIAL 1 2 3 4 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Area of collecting tank (A) Time Taken (t) Rise (h) = Area 1 Area 2 = √ ( − ) = ℎ Average
53 7.0 DISCUSSION Obtained from the experiments conducted, does the coefficient discharge (Cd) influenced by the inner pipe diameter? Explain your answer.
54 VIRTUAL LAB EXPERIMENT Experiment Pipe Friction Objective To determine friction factor in pipes.
55 1.0 OBJECTIVES To determine friction factor in pipes. 2.0 EQUIPMENT Pipes having different diameter connected to a differential manometer, Stopwatch, A collecting Tank, and Scale 3.0 MATERIALS & CONSUMABLES Water 4.0 INTRODUCTION When a gas or a liquid flows through a pipe, the flow of fluid through a pipe is resisted by viscous shear stresses within the fluid and the turbulence that occurs along the internal pipe wall. Due to this, there will be a loss of pressure in the fluid because energy is required to overcome the viscous or frictional forces exerted by the walls of the pipe on the moving fluid. In addition to the energy lost due to frictional forces, there will be a loss in energy when the fluid flows through fittings, such as valves, elbows, contractions, and expansions. This loss in pressure is mainly due to the local flow separation as it moves through such fittings. The pressure loss in pipe flows is commonly referred to as head loss. The frictional losses are mainly caused in a straight pipe, friction loss induced in fittings, such as bends, couplings, valves, or transitions in hose or pipe accounts for minor losses. The frictional losses are referred to as major losses (hf) while losses through fittings, etc, are called minor losses (hm). Together they make up the total head losses (h) for pipe flows. PIPE FRICTION
56 Figure 1: Types of fittings In practice, loss in a pipe flow comes into the picture in cases like calculation of a rate of flow in the pipes connecting two reservoirs at different levels or to calculate the additional head required to double the rate of flow along an existing pipeline. These pipe losses are dependent on the number of factors like the viscosity of the fluid, the size of the internal pipe diameter, the internal roughness of the inner surface of the pipe, the change in elevation between the ends of the pipe, the material of the pipe and the length of the pipe along which the fluid travels. Pipes with smooth surface does not account for larger friction loss, whereas pipes with less smooth walls such as concrete, cast iron, and steel fluid require large energy to overcome the friction-induced in a pipe due to the viscosity of a liquid. Rougher the inner wall of the pipe more will be the pressure loss due to friction. Figure 2 : Internal surface of smooth and rough pipes Friction loss in pipe The friction loss in uniform, straight sections of pipe, known as "major loss", is caused by the effects of viscosity, the movement of fluid molecules against each other, or the (possibly rough) wall of the pipe. Here, it is greatly affected by whether the flow is laminar or turbulent. Laminar Flow: It occurs when the fluid flows in parallel layers without adjacent mixing between the layers. In this type of flow, there are neither eddies nor cross currents, with fast flow over the center part of the pipe and no movement near the pipe surface. The roughness of the pipe surface influences neither the fluid flow nor the friction loss. For laminar flow Reynolds number (Re) < 2100.
57 Turbulent Flow: It occurs when the liquid is moving fast with mixing between layers. The speed of the fluid at a point continuously changes both magnitude and direction. For turbulent flow Reynolds's number 2100 < Re < 4000 Transitional flow is a mixture of laminar and turbulent flow, with turbulence flow in the center of the pipe and laminar flow near the edges of the pipe. Each of these flows behaves in different manners in terms of their frictional energy loss while flowing and have different equations that predict their behavior. For transitional flow Reynolds's number Re > 4000. It is useful to characterize that roughness as the ratio of the roughness height k to the pipe diameter D, the "relative roughness". Three sub-domains pertain to turbulent flow: • In the smooth pipe domain, friction loss is relatively insensitive to roughness. • In the rough pipe domain, friction loss is dominated by the relative roughness and is insensitive to Reynolds number. • In the transition domain, friction loss is sensitive to both. The Darcy Equation is a theoretical equation that predicts the frictional energy loss in a pipe based on the velocity of the fluid and the resistance due to friction. It is used almost exclusively to calculate head loss due to friction in a turbulent flow. h = 2 2 Where: hf = Friction head loss f = Darcy resistance factor L = Length of the pipe D = Pipe diameter v = Mean velocity g = acceleration due to gravity 5.0 PROCEDURES 1. Scan QR Code below to access Simulation Lab.
58 2. Click Simulator to start Virtual Lab 3. Open Friction in Pipes experiment, a window will appear as shown. 4. Select the required diameter of the pipe, then click the NEXT button.
59 5. Click on the selected pipe inlet valve to allow the flow through it. 6. Click on the main inlet valve to allow the flow through it and then click on the pipe valve to allow water flow to test for air bubbles. 7. Click on knot to change from isolated position to air-vent position and again click to change it to read position
60 8. Now click on the tank outlet valve to open and allow flow, note the manometer reading. 9. Here click on the tank outlet valve to close and then calculate the Head Loss value. 10. Fill in the value of Head Loss and then click CHECK
61 11. Calculate the discharge, velocity and analytical friction factor with the help the observation given here. 12. Repeat the same procedure for other trials. 6.0 RESULT Table 1: 50 mm pipe inner diameter Pipe inner diameter (mm) 50 mm TRIAL 1 2 3 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Length Of Pipe (I) Area of collecting tank (A) Time Taken (t) Rise (h) = Velocity = Analytical Friction Factor, f =
62 Table 2: 40 mm pipe inner diameter Pipe inner diameter (mm) 40 mm TRIAL 1 2 3 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Length Of Pipe (I) Area of collecting tank (A) Time Taken (t) Rise (h) = Velocity = Analytical Friction Factor, f = Average Analytical Friction Factor, f Table 3: 25 mm pipe inner diameter Pipe inner diameter (mm) 25 mm TRIAL 1 2 3 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Length Of Pipe (I) Area of collecting tank (A) Time Taken (t) Rise (h) = Velocity = Analytical Friction Factor, f = Average Analytical Friction Factor, f
63 Table 4: 20 mm pipe inner diameter Pipe inner diameter (mm) 20 mm TRIAL 1 2 3 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Length Of Pipe (I) Area of collecting tank (A) Time Taken (t) Rise (h) = Velocity = Analytical Friction Factor, f = Average Analytical Friction Factor, f Table 5: 15 mm pipe inner diameter Pipe inner diameter (mm) 20 mm TRIAL 1 2 3 Left Limb (LL) Reading (cm) Right Limb (RL) Reading (cm) Head Loss H (cm) =12.6 x (LL –RL) Length Of Pipe (I) Area of collecting tank (A) Time Taken (t) Rise (h) = Velocity = Analytical Friction Factor, f = Average Analytical Friction Factor, f
64 7.0 DISCUSSION Obtained from the experiments conducted, does the friction factor influenced by the inner pipe diameter? Explain your answer.
65 WRITTING TECHNIQUES CONCLUSION
66 The conclusion is a section that provides a message summing up what has been learned from the experiment but it should be short and to the point. All experiment goals must be restated. Besides, include any final data and notes on whether the experiment successfully answers the questions posed by your experiment. 2. Briefly restate the goal or objective of the experiment Start the conclusion by note all objectives of the experiment as a brief overview of experiment. For example, let's say you experimented with finding the Viscosity of Fluids. Therefore, you would state that your experiment's goal was to find the viscosity for different fluids. You would also include your prediction of which fluid has the highest viscosity, based on your previous knowledge of fluid mechanics. 3. Identify the main findings In a few sentences, summarize the results that get at in the experiment. Summarize the data here. Do not restate all the data from your experiment, only note any final data determined from analysis. The conclusion should also provide a brief explanation of what the final data from your experiment indicates. Also, report any possible sources of error in data and analysis have done. 4. State Whether Your Experiment Succeeded Finally, examine the data based on objective and predictions for the experiment. State whether the results of the experiment, answer the questions set out in the introduction. If we're successful, state so but if not, provide a possible explanation for why your experiment was unable to answer these questions. Nevertheless, whether the experiment was successful or not, state what you've learned from the experiment. CONCLUSION
67 WRITTING TECHNIQUES REFERENCES FORMAT
68 1.0 WEBPAGE Students can use documents from websites such as PDF or PPT and HTML webpage. The writing format is as below. a. PDF on a web site PDF documents are not likely to change, therefore don't include a date of retrieval. Author, A. (date). Title of document. Retrieved from http://xxx b. PowerPoint slides available online (PPT) PPT documents are not likely to change, therefore don't include a date of retrieval. Author, A. (date). Title of document[Format description]. Retrieved from http://xxx c. Webpages – HTML ( no date given) HTML websites are likely to change or be updated therefore do usually include a date of retrieval. Author, A. (n.d). Title of document. Retrieved date, from http://xxx d. Webpages – HTML ( date given) HTML websites are likely to change or be updated therefore do usually include a date of retrieval. Author, A. (date). Title of document. Retrieved date, from http://xxx REFERENCES FORMAT Ministry of Health. (2010). Customary tattooing guidelines for operators. Retrieved from http://www.moh.govt.nz /moh.nsf/pagesmh/10068/$File/customary-tattooingguidelines-for-operators-apr2010v2.pdf Sontheimer, R. (2009). Changes in APA formatting: APA 6th edition [PowerPoint slides]. Retrieved from http://www.writing.ku.edu/~writing/guides/documents- /NewAPA.ppt Flesch, R. (n.d.). How to write plain English. Retrieved April 12, 2009, from http://www.mang.-canterbury.ac.nz/writing_guide/writing/flesch.shtml Flesch, R. (2007). How to write plain English. Retrieved April 12, 2009, from http://www.mang.-canterbury.ac.nz/writing_guide/writing/flesch.shtml
69 2.0 Book There are two types of book that can be referenced which is print books and e-book. a. Print books A printed book is a literary publication comprising of pages bound together along a single side and, protected by a cover. It has contained both footnotes and end-notes. Author, Initial. (Year). Book title. City of publication, Country/State: Publisher. b. E-book The eBook is a book that is transformed into electronic form, for reading on a dedicated e-reader or computer and handheld devices. Author, Initial. (Year). Book title. Retrieved from http://xxx One author Gambles, I. (2009). Making the business case: Proposals that succeed for projects that work. Farnham, England: Ashgate. Two or more author Gazda, G. M., Balzer, F. J., Childers, W. (2005). Human relations development: A manual for educators (7th ed.). Boston, MA: Pearson Educational. Knox, P. L., & Mayer, H. (2009). Small town sustainability: economic, social, and environmental innovation. Retrieved from http://www.ebookcentral.-proquest.com
70 REFERENCES Cengel, Y. A., and Cimbala, J. M., (2017). Fluid Mechanics: Fundamental and Application Fourth Edition. McGraw-Hill Eucation, Hibbler R.C (2017). Fluid Mechanics (2nd Edition). Pearson Yahaya Ramli., (2017). Mekanik Bendalir Teori dan Penggunan. Edisi Pertama. UTM Press Janna W.S, (2015). Introduction to Fluid Mechanics Fifth Edition. CRC Press Taylor & Francia Group. Vlab Dev, (n.d). Study of different pressure measuring device, Retrieved June 12, 2020, from http://vlabs.iitb.ac.in/bootcamp/labs/fd/exp10/exp/simulation.php Vlab Dev, (n.d). Friction in Pipes, Retrieved June 13, 2020, from http://fm-nitk.vlabs.ac.in- /exp4/index.html# Vlab Dev, (n.d). Venturimeter, Retrieved June 14, 2020, from http://fm-nitk.vlabs.ac.in- /exp5/index.html# AUT Library,(n.d) APA 6th Referencing Style Guide, Retrieved December 10, 2020, from https://aut.ac.nz.libguides.com/APA6th/referencelist OLABS, (n.d) Viscosity of a liquid - Stoke's method, Retrieved December 20, 2020, from http://amrita.olabs.edu.in/?sub=1&brch=5&sim=225&cnt=4
Fluid Mechanics Laboratory Experiments and Demonstrations is provided as a manual handbook for student in conducting laboratory experiment related to the basic of Fluid Mechanics. Key features : ▪ Based on latest Polytechnic syllabus that meets the requirements of MQA and JPP. ▪ Provide three method of conducting experiment which is Practical experiments, DIY experiments and Virtual laboratory Experiments. ▪ Step-by-step standard operating procedure (SOP) of various experiments which include objective, theory, experimental setup, procedure, observations, and calculation to be plotted. ▪ Observation sheet is included in each experiment to record data obtained during the experiment. Chicha Bagu is a senior lecturer at the Department of Mechanical Engineering, Politeknik Kota Kinabalu. Having been a course coordinators of Fluid Mechanics for the past 15 years. Hatimi binti Mudin is a senior lecturer at the Department of Mechanical Engineering, Politeknik Kota Kinabalu. She has over 15 years of experience in teaching Fluid Mechanics. MECHANICAL ENGINEERING DEPARTMENT