Strictly speaking, the friction factor, depends on the type of soil, the. The friction factor relationship for highreynoldsnumber fully developed turbulent pipe flow is investigated using two sets of data from the princeton superpipe in the range 31. Some commonly used equations for calculating the fanning friction factor. A concise history of the darcyweisbach equation has been written by brown 5. In all other aspects they are identical, and by applying the conversion factor of 4 the friction factors may be used interchangeably. Plain fin performance has been analyzed with the help of cfd by changing the various parameters of the fin, colburn j and fanning friction f factors are calculated. Fanning friction factor unless otherwise indicated. D, the friction factor of the commercial pipe is found to be different from those obtained from the sand roughness used by nikuradse see figure 2. The fanning friction factor and the reynolds number may also be used to determine turbulent flow behavior of nonnewtonian fluids, provided that suitable flow parameters are used. It can be used to predict pressure drop or flow rate down such a pipe. Fanning friction factor an overview sciencedirect topics. Oct 22, 2012 an introduction to the famous moody chart.
In this case, the friction factor of the fanning equation can be calculated using the hagenpoiseuille equation see poiseuille flow. These factors can be determined experimentally but are more often taken from charts and diagrams. Fanning friction f and colburn j factors of a louvered. Of the two, the fanning friction factor is the more commonly used by chemical engineers and those following the british convention. It is easy to mix the two and calculate 400% greater or 25% less head loss. They found that the relationship between the reynolds number and fanning friction factor for foam was the same as that of a singlephase fluid. However, you must still enter an e for the program to run even though e is not used to compute f. Read through till the end to get you concepts of fluid friction and moody diagrams clear. If the flow is transient 2300 apr 12, 2020 the fanning friction factor is an element in the calculation of pressure loss due to friction in a pipe. The friction factor is defined as the ratio between the force required to move a section of pipe and the vertical contact force applied by the pipe on the seabed. Two variants of the friction factor are in common use.
If the flow is transient 2300 pdf reader applications without any pixellation and are available in greyscale, or with coloured lines that make reading easier. Friction factors for smooth pipe flow caltech authors. The hydraulic diameter of the louvered fin is calculated from. The work of many others including poiseuille, hagen, reynolds, prandtl, colebrook and white have contributed to the development of formulae for calculation of friction factors and head loss due to friction. Some friction factor graphs are for moody friction factor, which is 4 times fanning friction factor. Fanning friction factor there are two common friction factors in use, the darcy and the fanning friction factors. This the only difference between these two factors. Some textbooks may define f a little differently, resulting in a numerical. Equation 6 gives the friction factor f for cylindrical circular crosssection pipes. It is defined as the ratio between the local shear stress and the local flow kinetic energy density. It is a function of the roughness of the pipe and the level of turbulence within the liquid flow. Friction factor correlations for laminar, transition and turbulent flow in smooth pipes by daniel d.
In the transition region where the friction factor depends on both reynolds number and the relative roughness. Fanning friction factor for turbulent flow through circular pipes. This is also called the darcyweisbach friction factor, resistance coefficient, or simply friction factor the friction factor has been determined to depend on the reynolds number for the flow and the degree of. Darcy friction factor formulae in turbulent pipe flow. While the darcy factor is more common in general engineering, it can simply be shown to be 4 times as big as the fanning friction factor, so be careful which is which. In all other aspects they are identical, and by applying the conversion factor of 4 the friction factors may be used. Moody chart or moody diagram the engineering concepts. The darcy friction factor which is 4 times greater than the fanning friction factor.
The fanning friction factor, named after john thomas fanning, is a dimensionless number used as a local parameter in continuum mechanics. Use the equation method for defining re after the first friction factor equation. D, which moody plotted, and the fanning friction factor f. The fanning friction factor is defined by the pressure drop. Pressure loss in fluid flow through pipe occurs due to friction between the fluid and the. In fluid mechanics, the moody chart or moody diagram is a graph which relates the darcyweisbach friction factor f d, reynolds number re, and surface roughness for fully developed flow in a circular pipe it can be used to predict pressure drop or flow rate down such a pipe. Data correlation for friction factor in smooth pipes. For pipe flow, as long as entrance effects, roughness, and. Equations can be found in discussion and references for closed conduit flow. The correlations have been developed between reynolds number re, fin height h, fin. Friction factor calculations the darcyweisbach equation, for calculating the friction loss in a pipe, uses a dimensionless value known as the friction factor also known as the darcyweisbach friction factor or the moody friction factor and it is four times larger than the fanning friction factor. For laminar flow re friction factor was independent of the surface roughness and it varied linearly with the inverse of reynolds number. Apr 29, 2012 the difference between the two friction factors is that the value of the darcy friction factor is 4 times that of the fanning friction factor.
Fanning friction factor for turbulent flow through. Fanning friction factor formul this friction factor is onefourth of the darcy friction factor, so attention must be paid to note which one of these is meant in the friction factor chart or equation consulted. The friction factor fis a dimensionless term in the darcyweisbach equation, equation 1 or equation 2. The equations employed in evaluation of the fanning friction f factor and colburn j factor are given. Reynolds number based on internal diameter of the tube, dimensionless. This question does not arise with newtonian fluids, because viscosity does not vary with rate of shear, so. The moody friction factor f is used in the darcyweisbach major loss equation. If the darcy friction factor must be known only once, the moody diagram is good.
If the value of the reynolds number is known, f can be calculated from 6 and the viscous dissipation w f follows from 5. This simplified model coulomb is used to assess stability and requires an estimate of the friction factor. Friction factor of commercial pipes can be calculated using equation 5 if the pipe roughness is in the completely rough region. The fanning friction factor, named after john thomas fanning, is a dimensionless number used as a local parameter in continuum mechanics calculations. Friction factor measurements in metal mines measurements of airway friction factors were obtained. Jul 22, 2017 fanning friction factor the friction factor is found to be a function of the reynolds number and the relative roughness. Many folks calculate 4 times greater head loss or 4 times less than the actual friction loss. The frictional head loss in pipes with full flow may be calculated by using the following formula and an appropriate fanning friction factor. The equations employed in evaluation of the fanning friction f factor and colburn j factor are given below. What is the difference between fanning and moody friction. Part of the pressure change is due to elevation change and part is due to head loss associated with frictional effects, which are given in terms of the friction factor. The exact solution of the darcy friction factor in turbulent ow is got by looking at the moody diagram 5 or by solving it from the colebrook equation 1. Department of chemical and biomolecular engineering. Yang a,c a department of aerospace engineering and mechanics, university of minnesota, mn 55455, usa b department of mechanical and aerospace engineering, university of california, irvine, ca 92617, usa.
Data correlation for friction factor in smooth pipes, f. What is the use of having two friction factors darcy. The drag coefficient is a more general dimensionless group that is the ratio of the total normalized drag i. The darcy equation is a theoretical equation that predicts the frictional energy loss in a pipe based on the velocity of the fluid and the resistance due to friction.
The fanning friction factor, named after john thomas fanning, is a dimensionless number. Development of colburn j factor and fanning friction. Chapter 3 flow analysis memorial university of newfoundland. For third friction factor equation it is t bar in equation but only t in definitions. The basics of fluid mechanics involve all these types of question. Make sure variables in equation match variable in key. Numerical investigation of heat transfer and friction factor. Feb 27, 2011 they always pointed out the relationship to the fanning friction factor, and in the more recent editions the moody friction factor as well. Fanning friction f and colburn j tube compact heat exchanger. To download the notes i use for these videos, please click the following link. They always pointed out the relationship to the fanning friction factor, and in the more recent editions the moody friction factor as well.
The coefficient can be estimated with the diagram below. Fanning friction factor the frictional head loss in pipes with full flow may be calculated by using the following formula and an appropriate fanning friction factor. The darcy friction factor is a dimensionless quantity used in the darcyweisbach equation, for the description of frictional losses in pipe or duct as well as for openchannel flow. A simplified model for predicting friction factors of laminar. In the past, there has been some question as to what parameter to use for viscosity in the reynolds number. This is due to the fact that even though fanning friction factor f decreases with the increase in re this drop is nonlinear, and the corresponding increase in nu or is not sufficient to make the value of jf large huzaayin et al 2009 in other words, the relative frictional penalty increases with re to limit or reduce enhancement that would yield high area goodness factor furthermore, as. The fanning friction factor, named after john thomas fanning, is a dimensionless number, that is onefourth of the darcy friction factor, so attention must be paid to note which one of these is used as the friction factor.
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