Rough pipe

For smooth pipe, the friction factor is a function only of the Reynolds number. In rough pipe, the relative roughness /D also affects the friction factor. Figure 6-9 plots/as a function of Re and /D. Values of for various materials are given in Table 6-1. The Fanning friction factor should not be confused with the Darcy friction fac tor used by Moody Trans. ASME, 66, 671 [1944]), which is four times greater. Using the momentum equation, the stress at the wall of the pipe may be expressed in terms of the friction factor ... [Pg.636]

The Colebrook foriTuila (Colebrook, y. Inst. Civ. Eng. [London], II, 133-156 [1938-39]) gives a good approximation for the/-Re-( /D) data for rough pipes over the entire turbulent flow range ... [Pg.636]

In laminar flow,/is independent of /D. In turbulent flow, the friction factor for rough pipe follows the smooth tube curve for a range of Reynolds numbers (hydrauhcaUy smooth flow). For greater Reynolds numbers,/deviates from the smooth pipe cui ve, eventually becoming independent of Re. This region, often called complete turbulence, is frequently encountered in commercial pipe flows. The Reynolds number above which / becomes essentially independent of Re is (Davies, Turbulence Phenomena, Academic, New York, 1972, p. 37) 20[3.2-2.46ln( /D) ... [Pg.637]

For rough pipes, the velocity pronle in the turbulent core is given by... [Pg.637]

The friction factor depends on the Reynolds number and duct wall relative roughness e/D, where e is the average height ol the roughness in rhe duct wall. The friction factor is shown in Fig. 9.46. For a Urge Reynolds number, the friction factor / is considered constant for rough pipe surfaces. The friction pressure loss is Ap c. ... [Pg.766]

Relative roughness, pipe, 132 Friction losses, 181 also see Chapter 2 Friction, head loss, 68 Compressible fluids, 101 Factor, 68 Vacuum lines, 131 Gas constants, R, 378 Gravity settlers, 228 Head, 180-200 Calculations, 183, 184, 185 Discharge, 180, 187 Friction, 183 Liquid, 183... [Pg.627]

Region 3 (Re > 3000) corresponds to turbulent motion of the fluid and R/pu2 is a function of both Re and e/d, with rough pipes giving high values of R/pu2. For smooth pipes there is a lower limit below which R/pu2 does not fall for any particular value of Re. [Pg.66]

Region 4 corresponds to rough pipes at high values of Re. In this region the friction factor becomes independent of Re and depends only on (e/d) as follows ... [Pg.67]

Cope, W.F. Ptvc. Inst. Mech. Engrs. 45 (1941) 99. The friction and heat transmission coefficients of rough pipes. [Pg.563]

Rotational or vortex motion in a fluid 50 Rough pipes 67, 707... [Pg.890]

Rf = ratio of rough pipe friction factor to smooth pipe friction factor, 1.0-2.9... [Pg.420]

For fully developed turbulent flow in rough pipes,/is independent of the Reynolds number, as shown by the nearly constant friction factors at high Reynolds number in Figure 4-7. For this case Equation 4-33 is simplified to... [Pg.123]

Thus the velocity of the liquid discharging from the pipe is 3.66 m/s. The table also shows that the friction factor/changes little with the Reynolds number. Thus we can approximate it using Equation 4-34 for fully developed turbulent flow in rough pipes. Equation 4-34 produces a friction factor value of 0.0041. Then... [Pg.129]

Calculate a new expression for Dopt if / = 0.005 (rough pipe), independent of the Reynolds number. Compare your results with these from Problem 1.18 for ft = 1 cP and p = 60 lb/ft3. [Pg.35]

In all the tests described above smooth pipes or vessels have been used. Some experiments described below used rough pipes In Ref 15, pp 188-91 are described experiments conducted in Russia by K.I. Shchel-kin V.E. Ditsent in which it was brought to light a new combustion regime, almost similar in its characteristics to the detonation regime described under "Detonation (or Explosion) of Gases, etc ... [Pg.159]

Table 4 Comparison of Flame Velocities in CO-Air Mixtures in Smooth and Rough Pipes...

The anomalous behavior of combustible gases in rough pipes is explained in Ref 15, pp 188-91- Its theoretical background was... [Pg.159]

Fig B. Propagation of Flame Reaction Zone in Rough Pipes... [Pg.160]

More detailed discussion on Combustion in rough pipes is given on pp 190-91 of Ref 15 (See also "Detonation and Explosion of Dusts and "Detonation and Explosion of Gases and Vapors )... [Pg.160]

I.Ya. Shlyapintokh, DoklAkadN 65, 871 (1949) (Ignition of expl gaseous mixts in shock waves) 3b) V.E. Ditsent K.I. Shchelkin, ZhFizKhim 19, 21(1949) (Rapid combustion of gases in rough pipes)... [Pg.160]

K) Zel dovich Kompaneets(1960), 109-32 (Combustion with an induced ignition velocity) 188-91 (Combustion regime of Ditsent Shchelkin for gases in rough pipes)... [Pg.171]

The values reported in Table A are those for detonations conducted in smooth pipes of diam ca 10 cm. The velocities in these cases are not much smaller than the thermodynamic velocity , D = /2(k2-l)Q, where Q is chemical energy and k=Cp/cy, If experiments are conducted in rough pipes, the velocities are lower and in some cases can be as low as 40-50% of thermodynamic values (Ref 7, p 187)... [Pg.361]

The opposite conclusion would presumably apply to dilatant fluids and for these the pressure drop in a rough pipe may perhaps exceed that for a Newtonian fluid. A similar situation might also arise for Bingham-plastic and pseudoplastic materials which exhibit elastic recovery to a high degree. [Pg.108]

Virk PS (1971) Drag reduction in rough pipes Fluid Mech 45 225... [Pg.165]

For motionless mixers, energy is extracted from mean flow. Data can be correlated using an analogy with a rough pipe ... [Pg.244]

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