However the establishment of the friction factors was still an unresolved issue which needed further work. Newly developed friction factor correlation for pipe flow and. Fanning friction factor unless otherwise indicated. At high reynolds number, the friction factor of rough pipes becomes constant, dependent only on the pipe roughness. The darcy friction factor which is 4 times greater than the fanning friction factor used with weisbach equation has now become the standard head loss equation. The darcy friction factor is four times greater than the fanning friction factor.
Experimental analysis of pressure drop and laminar to. One should be cautious about friction factor charts as the moody friction factor is four times that of the fanning friction factor. This pa per describes the numerical this pa per describes the numerical analysis to study the heat transfer coefficient and friction factor of serrated fins in water medium. It is common in industry to define and use a fanning friction factor ff.
Fanning friction factor for turbulent flow through circular pipes. The final equation correlates the friction factor to the reynolds number and relative roughness by. The piping complexity factor fcis calculated from the diameter, straight pipe head, head for other fittings and for valves other than control valves, entrance head, exit head, velocity, fanning friction factor, and length l 15. This the only difference between these two factors. Aug 11, 2017 when solving many fluid dynamics problems, be it steady state or transient, the darcyweisbach friction factor, f, is necessary. If the darcy friction factor must be known only once, the moody diagram is good. Fanning friction f and colburn j factors of a louvered fin and flat tube compact heat exchanger. Pressure loss in pipe systems darcy friction factor tec. There are two common friction factors in use, the darcy and the fanning friction factors. Fanning 18371911 was apparently the first to effectively combine. In order to guarantee the complete hydration of the the friction losses in straight portions of the piping system are based on the fanning friction factor, f, and are represented by the first term at the right of equation 2, where v is the average flow velocity, d is the inside diameter of the tube and l. Newly developed friction factor correlation for pipe flow. It is easy to mix the two and calculate 400% greater or 25% less head loss.
The fanning friction factor, named after john thomas fanning, is a dimensionless number used as a local parameter in continuum mechanics. The fanning friction factor differs from the darcy friction factor by a factor of 4. The fourth formula is used to calculate the diameters of pipes given its lengths, head losses, absolute roughness, the kinematic viscosity of the fluid that flows in the. The moody friction factor is four times larger than the fanning friction factor. Theory and design of dilute phase pneumatic conveying systems.
Pq or we can relate it to the head loss due to pipe friction via power. For a laminar flow, the relationship between the friction factor f and reynolds number. Pressure drop for fully developed turbulent flow in. Fanning friction factor f defined as the friction force per unit surface area divided by the kinetic energy per unit volume. Thus, care should be taken when using unfamiliar equations or data since use of ff in equations developed for the darcy friction factor will result in significant errors. Do the experimental values compare to what is expected based on theory. Click here for full pdf version of this article includes al. Based on the literature correla tion, calculate the reynolds number and pipe pressure drop in psi for 1. Thus, care should be taken when using unfamiliar equations or data since use of ff in equations developed for the darcy friction factor will result in significant errors a factor of 4. Darcy friction factor formulae in turbulent pipe flow. Of the two, the fanning friction factor is the more commonly used by chemical engineers and those following the british convention.
Ech 4224l unit operations lab i fluid flow fluid flow. For laminar flow re friction factor was independent of the surface roughness and it varied linearly with the inverse of reynolds number. In order to be sure that the appropriate diagram is being used, the user can examine the laminar region. Determining friction factors for the colebrook equation requires either. The common formula for calculating the loss of head due to friction is darcys one.
The factor 2 appears because the fanning friction factor is employed. Pipe diameter and length also are mitigating factors in this equation. If the darcy friction factor is used, the factor becomes 8. Wall friction loss jkg international university department of food technology food engineering principles slide no. Note that the m and f subscripts are not typically used. The colebrook equation is not explicit in friction factor and must be solved iteratively for some flow problems, as is discussed in most fluid mechanics textbooks. The development of the moody chart which enables engineers to plot the darcy friction factor and the use of the personnel computer to calculate the darcy friction. Development of colburn j factor and fanning friction factor. Friction factors fanning did much experimentation to provide data for friction factors, however the head loss calculation using the fanning friction factors has to be applied using the hydraulic radius equation not the pipe diameter.
However, there are various handbooks and software available that calculate friction pressure inside the pipe considering the impacts of fr concentration. Pdf engineering friction losses in valves and fittings. 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. Pressure loss in pipe systems darcy friction factor. Data correlation for friction factor in smooth pipes.
Moody factor can be calculated from fanning factor with the following formula. Along each curve on the moodys diagram that is, curves. Once the fanning friction factor is obtained, the pipe friction pressure can be calculated. Using a structure very similar to that of moodys diagram, variants with the darcy friction factor and the fanning friction factor have been prepared. The subscripts are being used in this book to avoid confusion between the two different. Fanning friction factor for turbulent flow through. The reynolds number of a flow is a ratio of the fluids inertia force to the fluids viscosity force, which can be calculated using the formula.
The correlations have been developed between reynolds number re. A common definition for tube banks is given the symbol ftb. Site fanning friction factor equation delta h use consistent formatting for defining variables. For the system in this assignment, the fluid leaving the pipe is somewhat. Oil and gas pipeline design, maintenance and repair. For third friction factor equation it is t bar in equation but only t in definitions. The mixture friction factor fm and the mixture reynolds number re definitions. The darcy friction factor resistance coefficient is a dimensionless similarity parameter to describe the pressure loss in straight pipe sections. Use the equation method for defining re after the first friction factor equation. Development of heat transfer coefficient and friction.
Department of chemical and biomolecular engineering. Fanning friction f and colburn j tube compact heat exchanger. Yang department of aerospace engineering and mechanics, university of minnesota, minneapolis, 55455 department of mechanical and aerospace engineering, university of california, irvine, 92617 july, 2008 in this paper we derive an accurate composite friction. Development of colburn j factor and fanning friction. Make sure variables in equation match variable in key.
The frictional head loss in pipes with full flow may be calculated by using the following formula and an appropriate fanning friction factor. Where f is the fanning friction factor, g is the mass flux of the twophase flow, and dh is the diameter of the tube. By defining the friction factor as a similarity parameter, the friction factor can be determined in a reduced model scale of the later pipe system. The major loss is that due to frictional resistance of the pipe, which depends on the inside roughness of the pipe.
Determining friction factors in turbulent pipe flow chemical. Some friction factor graphs are for moody friction factor, which is 4 times fanning friction factor. Pdf engineering friction losses in valves and fittings for. L is the pipe length, d is the inside pipe diameter, v is the fluid velocity averaged over the. What is the difference between fanning and moody friction. Fanning equation applicable to all flow regimes turbulent flow no exact mathematical derivation available empirical correlations are used.
This paper is aimed at determining the friction factor for commercial short and long peek microtubes with nominal internal diameters between 300 and 100 m and values of the lengthtodiameter ratio, ld, ranging between 167 and 5000. Discuss the effect of flow rate on the pressure drop. Doc mec2404 frictional flow in pipe lab report done by md. The fanning friction factor relates the shear stress to the average kinetic energy of the fluid. Kays and crawford 2 provide the following expression for the fanning friction factor for laminar flow in a round tube. This is just one method of pipe friction calculation, which can be very tedious and time consuming. Mec2404 frictional flow in pipe lab report done by. Pipe flowfriction factor calculations using excel spreadsheets. The piping complexity factor is greater than one when the piping is relatively dense with fittings and valves, and less. Description of video you can watch the playlist here or watch in hd, user friendly interface, more solved problems and slideshows h. Discuss the effect of flow rate on the pressure drop across the different pipes.
The reynolds number n re is first calculated where g is the gas viscosity in lbsftsec after this, the fanning friction factor is calculated using the following equation developed from the charts given in cranes technical paper no. Discuss the effect of flow rate on the pressure drop across. The power required to overcome friction is related to the pressure drop through. Che 4253 design i l d v f f 2 2 need to calculate the fanning factor and the equivalent lengths. Mar 24, 20 a numerical model has been developed for plain fin of plate fin heat exchanger. Heat transfer and pressure drop in the transition region of. It is related to the fanning friction factor by the equation 6. Frictional losses in a circular tube of constant diameter 4. What is the relationship between fanning friction factor and the reynolds number. Fanning proposed a correlation for the pressure drop as a function of surface. The relationship between the fanning friction factor and the moody friction factor is. Heat transfer and pressure drop in the transition region.
Theory and design of dilute phase pneumatic conveying. The increase in reynoldss number and the decrease in fanning friction factor support the theory based on the equation used for the fanning friction constant. After looking at all the data that was collected, the pressure drop increased by about 1. Four explicit formulae for friction factor calculations in. Flowregime based model for pressure drop predictions in. 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 data is processed for power laws and a composite expression is found as a rational. In general the smoother the pipe the less a pressure drops occurs because of the lower absolute roughness. Mar 29, 2021 fanning friction f and colburn j factors of a louvered fin and flat tube compact heat exchanger. 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.
The moody friction factor can be obtained by plotting the darcy friction factor as a function of reynolds number and relative roughness. The fanning friction factor will be used in this paper. The correlations have been developed between reynolds number re, fin height h, fin. The symbol f is commonly used for both the moody friction factor and the fanning friction factor. The equations employed in evaluation of the fanning friction f factor and colburn j factor are given below. The above grouping s is interpreted as the dimensionless mean wall shear stress. Table 3 lists error in friction factor values from the theoretical laminar line with. The fanning friction factor in the laminar region equals 6re. 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. Contrary to existing theory, he showed conclusively that the pipe friction factor was a function of both the pipe roughness and pipe diameter. Development of heat transfer coefficient and friction factor. Proceeding as in the development of the previous models would yield. In order to guarantee the complete hydration of the the friction losses in straight portions of the piping system are based on the fanning friction factor, f, and are represented by the first term at the right of equation 2, where v is the average flow velocity, d is the inside diameter of the tube and l the tube length. Note that moodys friction factor is sometimes called darcy or darcyweisbach friction coefficient.
Create a plot use excel or equivalent of the literature correlation of friction factor versus re for a smooth pipe for 10 7re10 6. A relationship between the friction factor and the reynolds number, pipe roughness, and inside diameter of pipe. There are many types of losses of head for flowing liquids such as friction, inlet and outlet losses. Moody chart showing the friction factor of darcyweisbach fd plotted against. Experimental determination of the friction factor in a tube. The basic approach to all piping systems is to write the bernoulli equation between two points, connected by a streamline, where the conditions are known. In this case, the friction factor of the fanning equation can be calculated using the hagenpoiseuille equation see poiseuille flow. Newly developed friction factor correlation for pipe flow and flow. The darcyweisbach equation or the fanning equation and the friction factor moody friction factor or fanning friction factor are used for a variety of pressure. Fanning friction factor an overview sciencedirect topics. Some commonly used equations for calculating the fanning friction factor. Friction factors for ducts have been compiled for both laminar and turbulent. Therefore, it is traditional to call f, the darcy f factor, even though darcy never proposed it in that form. Proposed correlations for laminar and transition friction factors 11 3.
Reprinted with permission from cep chemical engineering. Doc mec2404 frictional flow in pipe lab report done by. In circular pipes this factor can be solved directly with the swameejain equation, as well as others, however most of these equations are complicated, and become cumbersome when iteration is necessary. Generally 3 to 4 iterations are sufficient to converge on a reasonably good value of the friction factor f friction factor, dimensionless d pipe inside diameter, in.
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