EXAMPLE 6.2.4. APPLICATION OF MOODY DIAGRAM

What is the discharge capacity of 108-inch wood stave pipe of best quality carrying water at 60 degrees Fahrenheit with a loss of head of 8ft per mile?

The range of k values for wood stave pipe is from 0.0006 to 0.0030. Take the least to be conservative.

With diameter of 108 inches:   
                                                               

                                                             






To solve for friction factor, f, determine viscosity of fluid:

For water at   : 

The Reynold's number is evidently going to be large. For the roughness coefficient,


          

From Moody diagram: Try f= 0.01

So, velocity can be solved from head lost equation:


         

          
                         

With trial velocity known, solve for the Reynold's number: 

         

         

From the Moody Diagram, a more accurate f = 0.011 would be used.

So computing velocity from Darcy-Weisbach's equation:

          
                            


Thus the discharge can be computed as follows:

         

         





RELATED TOPIC:

6.2. GENERAL METHOD OF DETERMINING DARCY WEISBACH'S FRICTION FACTOR- THE MOODY DIAGRAM