Fluid flow momentum correction factor

MOMENTUM OF TOTAL STREAM MOMENTUM CORRECTION FACTOR. The momentum flow rate Aif of a fluid stream having a mass flow rate th and all moving at a velocity u equals mu. If u varies from point to point in the cross section of the stream, however, the total momentum flow does not equal the product of the mass flow rate and the average velocity, ot mV in general it is somewhat greater than this. 

AVERAGE VELOCITY, KINETIC-ENERGY FACTOR, AND MOMENTUM CORRECTION FACTOR FOR LAMINAR FLOW OF NEWTONIAN FLUIDS. Exact formulas for the average velocity V, the kinetic-energy correction factor a, and the momentum correction factor P are readily calculated from the defining equations in Chap. 4 and the velocity distribution shown in Eq. (5.11). 

Zeitsch recently pointed out and analysed the effect of the exchange of momentum between the feed entering a rotating bowl and the charge aheady in the bowl on the effective acceleration within the bowl. The feed slows down the rotation of the fluid in the bowl, and the lag between the bowl speed and that of the liquid surface in the bowl ranges in practice between 3 and 10%. Zeitsch concluded that the effect of the feed rate on separation efficiency is significant and derived a correction factor by which the nominal bowl speed has to be corrected to obtain the true effective centrifugal acceleration to which the particles in the flow are subjected. 

Frequently, tubes are omitted from the baffle window areas. For this configuration, maldistribution of the fluid as it flows across the bank of tubes may occur as a result of the momentum of the fluid as it flows through the baffle window. For this reason baffle cuts less than 20% of the shell diameter should be used only with caution. Maldistribution will normally be minimized if the fluid velocity in the baffle window is equal or less than the fluid velocity in crossflow across the bundle. This frequently requires baffle cuts greater than 20% of the shell diameter. For such cases, the number of tube rows in crossflow will be less than that assumed in the methods above consequently a correction is required. In addition, the pressure drop for the first and last baffle sections assumes tubes in the baffle windows the factor 2.66 in Equation 8.19 should be reduced to 2.0 for the case of 20% baffle cuts. 

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