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Unformatted text preview: Exercise #4 As a liquid moves through a horizontal pipe, the pressure drops due to friction between the liquid and the walls of the pipe. In order to calculate the actual pressure drop, it is necessary to somehow determine the friction factor ( f ). One possibility is to use a Moody chart (see the chart supplied). The inputs are R (the Reynolds number for the flow) and the relative roughness of the pipe ( ε /D, where ε is the roughness of the pipe walls and D is the diameter of the pipe). If there is no line on the chart for the particular ε /D of interest, interpolation is required (one must imagine the required line). Otherwise use of Moody charts is straightforward. The value of R is entered at the bottom of the chart and the value of f is read from the left hand scale. Moody charts are based on the Colebrook formula for f . They were once the primary source of friction factor information, but today, with computers and calculators at our disposal, it is just as easy (as much more accurate) to use the Colebrook formula directly. The Colebrook formula is given below. If ε , D, and R are all known, it is in principle possible to solve for...
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- Spring '11
- Friction, Roughness, Moody, right hand, Plug, Moody chart