1.0 TITLE:Laminar and Turbulent Flow

2.0 OBJECTIVE:The purpose of the Reynold experiment is to illustrate laminar, transitional (intermittently turbulent), and fully turbulent pipe flows, and to determine the conditions under which these types of flow occur. The equipment consists of a hydraulics bench, an Osborne Reynolds apparatus, dye, a stopwatch, a graduated cylinder. The diameter of the flow visualization pipe is d= 7.67mm.

3.0 THEORY:In viscous flow, there are 3 types of it. The Reynolds number is a primary way to investigate the type of flow. It is the ratio of inertial force (u) to viscous flow force (/L). This Reynolds number is used to determine whether the flow will be laminar or turbulent.The formula for Reynolds number is Re = (ud/) = Density of Fluid = Dynamic viscosity of fluidu = Norminal VelocityD = Diameter of pipe

There are 3 types of viscous flowRe < 2000 = Laminar Flow2000 < Re < 4000 = Transition FlowRe > 4000 = Turbulent Flow

4.0 PROCEDURE:1. Started the pump and establish a water flow through the test section. Raised the swivel tube of the outlet tank so that it is close to the vertical. Adjusted the bench regulating valve (or pump speed) to provide a small overflow from the inlet tank and overflow pipe. Ensure that any air bubbles are bled from the manometer tubes.1. Set up a series of flow conditions with differential heads starting at 25mm in step of 25mm up to 150mm and thereafter in steps of 50mm up to a maximum of 500mm. at each condition carefully measure the flow rate using volumetric tank and a stop watch.1. The water flow stopped, allowed the rest unit to drain and replace the inlet tank with the feedback. Connected the test section pressure tapping to the water mercury manometer. Established a water flow and bleed the manometer.1. A series of flow conditions with differential heads in steps of 25mm of mercury was set up. At each condition the volumetric flow rate was measured.1. Measured the water temperature.

Pipe dimension : 10.1mm

Diameter (m)0.01010.01010.01010.0101

Length (m)0.360.360.360.36

Area (m2)0.00008010.00008010.00008010.0000801

Fluid properties : Water

Dynamic Viscosity (kg m-1 s-1)0.0010.0010.0010.001

Density1000.001000.001000.001000.00

Temp 20202020

Recorded values:

Variable Outlet Head (mm)10.0015.0020.0025.00

Quantity of water collected (liter)3333

Time to collect water, t (s)60677077

Inlet head, hi (mm)20.0021.3022.9025.50

Outlet head, ho (mm)7.6010.8013.2017.80

Calculated value:

Volume flow rate, Q (m3/s)0.0000500.0000450.0000430.000039

Mean velocity, V (m/s)0.6240.5590.5350.486

ln V-0.472-0.582-0.626-0.721

Reynolds number, Re6302.3495643.8955402.0134910.921

ln Re8.7498.6388.5958.499

Friction head loss,hf (mm)12.4010.509.707.70

ln hf2.5182.3512.2722.041

friction factor, f0.006830.005780.005340.00424

ln f-4.987-5.153-5.233-5.464

Pipe dimension : 7.67mm

Diameter (m)0.00770.00770.00770.0077

Length (m)0.360.360.360.36

Area (m2)0.00004620.00004620.00004620.0000462

Fluid properties : Water

Dynamic Viscosity (kg m-1 s-1)0.0010.0010.0010.001

Density1000.001000.001000.001000.00

Temp 20202020

Recorded values:

Variable Outlet Head (mm)10.0015.0020.0025.00

Quantity of water collected (liter)3333

Time to collect water, t (s)27293234

Inlet head, hi (mm)26.2029.3032.2035.60

Outlet head, ho (mm)6.1012.2017.9023.30

Calculated value:

Volume flow rate, Q (m3/s)0.0001110.0001030.0000940.000088

Mean velocity, V (m/s)2.4042.2392.0291.909

ln V0.8770.8060.7070.647

Reynolds number, Re18442.33617170.45115560.72114645.385

ln Re9.8229.7519.6539.592

Friction head loss,hf (mm)20.1017.1014.3012.30

ln hf3.0012.8392.6602.510

friction factor, f0.008400.007150.005980.00514

ln f-4.779-4.941-5.120-5.270

Graph of ln Hf against ln V for 7.67mm

Graph of Ln Hf against Ln V

Figure 1 :Pipe 7.67mm

Figure 2 :Fluid Bench 1 and 2

5.0 SAMPLE CALCULATION

1.1 Volume flow rate

1.2 Mean Velocity

, where

1.3 Reynolds number

1.4 Friction Factor* Assuming roughness height is negligible

6.0 DISCUSSION

The purpose of this experiment is to investigate or to determine the turbulent and laminar flow in a pipe. Due to errors from the equipment and the human errors, the experiment was not as successful as it should be. There were a few problems that were occurring while the experiment was being conducted. A straight line graph was achieved which is a linear graph which is a straight line graph which is from the obtained results. One of the problems is there was some a little difference on the obtained data. This is because of there was a zero error on the equipment and the parallax error while taking the reading from the manometer. To solve the problems, we asked other students to crisscross or to check the result or the data obtained to make sure the accuracy. And the figure obtained was taken to be as little as 3 significant figures. And this is to remove or to avoid the inaccuracy of the obtained data. When we obtain the data from the graph of hf which is a straight line graph, hf can be expressed as v because hf = v-0.618.. But we did find out the flow was turbulent but we failed to investigate the laminar flow because the diameter of the pipe was too small and this made the manometer failed to give any data.After recording some readings while adjusting the speed or the velocity of the water going through the section with the pumps controller, the manometer did record some readings. But the overflow of the variable head was too small for the experiment.We need the velocity of the flow of the water to be a little lower with the velocity pump with smaller diameter variable outlet valve, and this is to allow the manometer to give out readings when the variable head overflows into the reservoir. Also, during the experiment, we were in a cold temperature room where the temperature was 22 but we were supposed to conduct the experiment in room temperature which is about 27. The temperature affects the viscosity of the fluid. If the temperature is high, the viscosity would be lower, and vice versa if the temperature is high.

7.0 CONCLUSIONThe obtained graph was supposed to be a straight line graph which is a linear graph. This made sure that the graph of log hf is directly proportional to log v. Due to parallax error and the zero errors which was obtained from the equipment, there were some difference during the reading of the manometer.Inlaminar flowthe motion of the particles of fluid is very orderly with all particles moving in straight lines parallel to the pipe walls. As the velocity of flow increases the fluid tends to fromLaminartoTransitionaltoTurbulentflow.The graph of log hf is directly proportional to log V. This relationship means that the head loss is always depending on the velocity of the flow. Layers of water flow over one another at different speeds with virtually no mixing between layers. The flow velocity profile for laminar flow in circular pipes is parabolic in shape, with a maximum flow in the center of the pipe and a minimum flow at the pipewalls. The average flow velocity is approximately one half of the maximum velocity. The turbulent flow is characterized by the irregular movement of particles of the fluid. The flow velocity profile for turbulent flow is fairly flat across the center section of a pipe and drops rapidly extremely close to the walls. Viscosity is the fluid property that measures the resistance of the fluid to deforming duetoashearforce. Formostfluids,temperatureandviscosityareinversely proportional.

8.0 Reference1.5 Dubbel, W. (1994). Werkstoffkunde and Werkstoffprufung (10th Ed). Dusseldorf: CornelsenVerlag, Berlin.1.6 J. M. Cimbala and Y.A. Cengel. (2008). Essentials of Fluid Mechancis, Fundamentals and Apllications. McGraw-Hill International Edition, Singapore.1.7 K.L Kumar. (2006). Engineering Fluid MEchancis. EURASIA PUBLISHINGHOUSE (P) LTD. Ram Nagar, New Delhi.1.8 Dr. R. K. Bansal. (2012), A Textbook of Fluid Mechanis, LAXMI PUBLICATION (P) LTD, New Delhi.