Assignment Lab

1. Abstra Abstract ct Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction such as fluid friction, dry friction friction and internal internal friction. friction. Fluid friction friction can be specifica specifically lly describ describes es the friction between layers of viscous fluid that are moving relative to each other. This experiment, Fluid Friction Apparatus is to study about the flow measurement techniques and losses in a variety variety of pipes pipes fittings. fittings. Then to calculat calculate e the pipe friction friction coeffic coefficient ient for differen differentt pipe material. It is consisted the relationship between the head loss due to the fluid friction and velocity for flow of the water to the different type pipe material for both laminar and turbulent flow flow. Accordi ccording ng to the head head loss loss formu formula, la, as veloc velocity ity,, V increa increase se head head loss, loss, h loss also increases. eynolds number was calculated to determine the behavior of the flow. In the pipe flow, laminar flow exist if e is less than !""" while turbulent flow exist when e bigger  than #""". If, the e number lies between !""" and #""" can be stated in transition flow. $ressure drop across the pipe, bends and other component that will effect head loss were than measured calculate the effective lengths. As what concluded in the conclusion, bends have greater turning radius compared to elbow. %ence, the loss coefficient value for bends is greater than elbow. The velocity of the several flow then was measured. Finally, the ob&ectives of the experiment achieved when all the data were obtained.

2. Introduc Introduction tion In hydrauli hydraulic c enginee engineering ring practice, practice, it is frequen frequently tly necessary necessary to calculat calculate e the head loss incurred by the fluid as it flows along a pipe. For example, it may be desired to predict the rate of flow along along a proposed proposed pipe connecti connecting ng two reservoi reservoirs rs at two differe different nt levels. 'r it may be necessary to calculate what additional head would be required to double the rate of  flow along an existing pipeline. %ead loss occurs at fittings such as bends or valves and by frictional resistance at the pipe wall. (here there are numerous fittings and pipe is short, the ma&or part of loss will be due to the local mixing near the fittings. For the long pipeline, on the other hand, friction on the wall of the pipeline will predominate. There are three ob&ectives of the experiment and the primary purpose was to evaluate fluid friction in pipes of different type of material which is stainless steel and $V). For the straight length of pipes, pressure drop measured were used to calculate the friction factor in those pipes. A negative relationship between friction factor and eynolds number was expected. *oreover, the relationship predicted to follow exponentially decreasing trends similar to 3

those found on turbulent section of the *oody chart, with higher friction factor values for the rougher pipes. 'n the other hand, the ob&ective was to measure pressure drop across piping components to determine effective diameter. In spite the fact that this data did not contribute itse itself lf to comp compar aris ison on to tabu tabula late ted d valu values es,, qual qualit itat ativ ive e diff differ eren ence ces s in pres pressu sure re drop drop contributions of each components was analysed. Finally, determination of head loss through pipe fittings. 3. Aims Aims +. To find the pressure drop pattern for different type of pipe material and diameter. !. To determine the pipe friction coefficient for different pipe material. 4. Theo Theory ry

h Ltotal= h Lmajor − hminor

The overall head loss for a pipe system consists of the head loss due to viscous effects in the straight pipes, named the ma&or head loss, h

  and the head of the various pipe  and

ma&or 

components named the minor head loss, h minor minor,, and the sum of the both of these losses ma-e up the total head loss li-e the equation given above. *a&or losses The head loss due to viscous effects in straight pipes is named the ma&or head loss and it is denoted by h ma&or  .  . The factor that effects the flow inside the pipes and the ma&or losses occur is the friction factor. The The friction factor will allow a variety of information regarding regarding pipe flow. For the turbulent flow the dependence of the friction factor on the eynolds number is much much more more comple complex x than than for lamin laminar ar flow flow. The The frict friction ion facto factorr for for the the lamina laminarr flow flow can can described as follows

f  =

64

ℜ

4

(here

f 

stand for the friction friction factor or the other other name is the /arcy friction friction factor. factor. In

 D laminar flow, the friction factor is independent of  ε  . The expresses the friction factor in turbulent flow is more complicated than laminar and it is called the )olebroo- equation

ε  D 2.51 + 3.7 ℜ √ f  1 =−2.0log f 

¿

(hile for the hori0ontal pipes, the change in pressure is a friction of the length and diame diamete terr of the pipes, pipes, and also the phys physica icall prope properti rties es of the fluid and the pipes. pipes.

In

hori0ontal pipes, the pressure drop occur due to the friction and the density of the fluid is written as bellow

∆ p= f 

2

1

 ρ V 

 D

2

For a vertical pipe it is expressed as follows 2

V  h Lmajor =f   D 2 g 1

If all of the new expres expressio sions ns are applied applied to the the energ energy y equa equatio tion, n, it obtai obtaine ned d the the expression as below

 P1− P2= γ ( z  z 2− z 1 ) + f 

1

 D

2

 ρ

 V 

2

1sually, the roughness of the pipe is depends on the type of the materials of the pipe, the ways it was produced or by schedule number. number. The roughness roughness is not as uniform and well defined as in the artificially roughened pipes used by 2i-uradse. %owever, it is possible to obtain a measure of the effective relative roughness of typical pipes and thus obtain the

5

friction factor. Typical roughness value for the various pipe surfaces are given in the table below

Table + oughness factor for difference material

The functional dependence of

f  on e is called the *oody )hart,

6

Figure ! *oody )hart *inor losses *inor head losses occur because of the presence of the pipe component. component. This loss can be very small or it can be infinite, infinite, as it would be in the case case of the closed valve. valve. The minor  loss coefficient is called as 3 , and it is described as below 2g 2

V  / ¿ ¿ ¿

 K  L =

h Lminor ¿

 Therefore, the change in pressure can be written as follows

∆ P= K  L

1 2

 ρ V  2 ρV  2

V  h Lminor = K  L 2g

7

The table below figures for minor loss coefficients.

Table ! oss coefficient for the pipe components

5. Appara Apparatus tus 8

• •

4alvani0ed pipe5 used for outdoor  )opper pipe5 used as home plumbing

+

•

6topwatch 1sed to measure the time ta-en

9

+. An in5 in5li line ne str strai aine nerr 7!8 7!8 !. An artificia artificially lly roughen roughened ed pipe 798 :. 6mooth bore pipes pipes of # different different diameters diameters 7;8, 7;8, 78 ?. A short short radiu radius s . A #?= @ @@ 7# 7#8 9. A #?= #?= elb elbow ow 7?8 7?8 ;. A