Friction loss along a pipe

Experiment : friction loss along a pipe


Aim                    : 1. To verify darcy`s law frictional flow through pipes.
                                   2.To determine the friction factor for a fully developed 
                                    turbulent  flow                                                   






Apparatus   : 1.pipe friction apparatus         2. Bucket
                                    3.Measuring cylinder               4.Spirit level
                                    5.Stop watch                              6.Ruler


Theory        : Darcy`s low for frictional head for   turbulent  flow  given 
                                              H_f = (λL /2gD )ⁿ
                                             H_{f  = fricion head loss}
                                             λ    = Friction factor
                                            L    = length of pipe
                                            v    = Velocity



 For fully developed turbulent  flow , friction factor is a constant.If the diameter remains same , between any given two section of a pipe L and are constant.
There fore, 
                                              H_f= kvⁿ  sa
                                                                               where k = λL / 2gD
hence,   
                               Log ₁₀ H_{f =}  n Log₁₀V + Log₁₀ k
                           ^                    ^         ^
                              y      =       mx      +  c


1.pot the  Log ₁₀ H_f  vs  Log₁₀V  and obtain value of  λ  and n




Procedure:  

• The control valve was opened and a steady flow rate was obtained
• The manometer readings h1 and h2 were recorded
• The outflow in a time interval at was collected and the volume ∆v was measured.
• The flow rate was adjusted by the control value and steps two and.there were repeated for different stendy flow rates
• The length of the pipe was measured 
• The diameter of the pipe D was recorded

 Calculation   : 
                    _{Sample calculation for obtain}  Log ₁₀ H_f  and  Log₁₀V 


For PVC pipe
         H_{D  = 210 mm}                 h_{u = 133 mm}


  

                         H_{f = (}H_{D -}h<sub>u) ( s -1)   s=Density of Hg /Density of water


                              =( 0.21 - 0.133 ) ( 13.6 -1)
                              = 0.970</sub>

           Log ₁₀ H_f  = - 0.0132


Area of the pipe = πd²/4
                               =2.01x 10^-4 m<sup>2


     Discharge (Q )   = Q/T
                           
          Velocity (v)  = Q/A</sup>