ABSTRACT

We determined various velocity profiles for different percentage of valve opening. From those we saw that for 10% valve opening the velocity profile became sharp. Because after entering air to the pipe for wall shear stress, thicker  sub layer, low velocity gradient and friction loss it became sharp. Within (10-50)% of valve opening laminar region may  exist. After 60% valve opening the profile became fuller or blunt. Because of high velocity gradient, thinner sub layer it became blunt. Within (60-100)% of valve opening the turbulent region may exist. This phenomenon was seen accumulating those profiles. For determining friction factor we found out average velocity from individual velocity profile. We calculated corresponding Reynolds number on the basis of average velocity. Within certain length we determined friction factor on the basis of pressure drop, average velocity, diameter and length. Plotting those data we obtained friction factor Vs Reynolds number graph. From graph we see that as Reynolds number is increased the friction factor decreases as long as the flow remains laminar. At transition friction factor increases sharply. In the turbulent flow regime, the friction factor decreases gradually and finally levels out at a constant value for large Reynolds number. Finally we obtained % of valve opening Vs Reynolds number graph. From it we see that as % of valve opening increases the average velocity increases, then Reynolds number increases and finally levels out at a constant value for large Reynolds number.

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