Objectives1. To investigate the head loss due to friction across bends and elbows.2 . T o fi n d t h e b e n d / e l b o w c o n s t a n t f o r g i v e n p i p e .

IntroductionMinor loss is caused when there is additional component is added to the straight pipe such as tees, elbows and bend. This minor loss will contribute to head loss due to the friction across bends and elbows. Bernoulli’s equation relates pressure, velocity and elevation between any two points in the flow. But since the equation have some restriction, a new term must be introduce.P1/ρg + V1/2g + z1= P2/ρg + V2/2g + z2+ hLHead loss is added because in real life situation there are losses. The head loss will increase when the fluid flow through fittings (elbows or bends) due to the friction effect that caused by the viscosity. This situation can be proved by calculation of the drop in the flow rate. Minor losses expressed in terms of loss coefficient, Kι and defined as: Kι = hι / (V²/ (2g). The values of Kι are related to the pipe friction factors by a constant which is dependent on the ratio of the bend radius to the pipe diameter R/D.Procedures1 . S t a r t t h e p u m p a n d w a i t ti l l t h e r e i s w a t e r fl o w .2 . R a i s e t h e s w i v e l t u b e .3. Adjust the bench regulating valve to provide a small overflow through both inlet tank and overflow pipe.4 . S e t a s e r i e s o f c o n d i ti o n a s i n T a b l e 1 . 5.Measure flow rate at each condition using stopwatch and volumetric tank.

6 . R e p e a t s t e p s 1 - 5 f o r p i p e w i t h e l b o w s .ResultsRequired volume of water, V = 3 liter = 0.003m3Diameter for both pipes, D = 0.003m3Temperature of water = 24 ºCCALCULATION: 1 . V o l u m e t r i c fl o w3L=0.003 m3Q (m3/s) = Volume (m3) / Time= (0.003m3) /42= 7.1428 x 10-5m3/s2 . A v e r a g e v e l o c i t yArea of pipe= π (D²/4) = π (0.01²/4) = 7.854x10-5m2 V (m/s) = Q/A= (7.1428 x 10-5m3/s)/ (7.854x10-5m2) = 0.909 m/s3 . R e y n o l d s # _ Reynolds # =ρ (kg/m 3) x V (m/s) x d (m) µ (Ns/m2)= (997.0x0.909x0.01)/ (0.891x10-³) = 10171.414. Frictional head loss hf (m)hf = h1(m) – h2(m) = 0.385m – 0.121m = 0.264m6. hf = f x (L/D) x (V2/2g)= 0.74 x (0.288m/0.010m) x (0.91m/s)2/2x9.81m/s= 0.9m for endsHead loss due to a single bendh b= (hL– hf ) / N= (0.120m – 0.0373m) / 4 = 0.0207 mElbow constant,

K b= (2gh b)/V2 = [2(9.81m/s2) (0.0207 m)] / (0.659m/s)2 = 0.9352K b from table A= 30f = 30(0.0312) = 0.936%diff = [(0.9352– 0.9360) / 0.9360] x 100% = 0.09%

DiscussionFor this experiment, we are using bend and elbows pipe to investigate the head loss in the pipe. Different from previous experiment when we use straight pipe, bends and elbows pipe will contribute to minor loss in the head loss. The losses in the bends and elbows are caused by the flow separation on the inner side of the pipes.And just like the previous experiment, we find that the fluid flow is also turbulent flow as the R e y n o l d N u m b e r s h o w s h i g h v a l u e s . T h i s i s b e c a u s e i n r e a l s i t u a ti o n s u c h a s h o m e p i p i n g i t i s impossible to have laminar flow since the velocity will be very low and the materials will be too expensive. We also realize that the time taken for the bends is shorter than the elbows for the fluid to rise until 3L. This is because bends will allow the fluid to make turn easily rather than elbows that will restrict the fluid to move fast. It is recommended to reduce head loss we use bends rather than elbows to have lower head loss to avoid any parallax error we must take reading from the height of the inlet. We also must take the re a d i n g i m m e d i a t e l y w h e n t h e v o l u m e t r i c t a n k fl o w s t o p . A l s o m a k e s u r e t o c o n n e c t s t h e p i p e correctly and make sure there is no leakage anywhere in the connection.ConclusionAlhamdulillah, we manage to carry out the experiment without any problem. The percentage error also is very small about 1% error which is acceptable. We also managed to observe the effect of bends and elbows pipe to the flow of fluid.References:1. Fluid Mechanics Laboratory Guidelines for Biotechnology Engineering Lab1, 3rd edition (Jan 2007), Syed Abu Bakar Al-Saggoff.2 . F l u i d M e c h a n i c s F u n d a m e n t a l a n d A p p l i c a ti o n s ,Y u n u s A . C e n g e l , J o h n M . Cimbala