Flow Rate

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flow rate

[′flō ‚rāt]
(fluid mechanics)
Also known as rate of flow.
Time required for a given quantity of flowable material to flow a measured distance.
Weight or volume of flowable material flowing per unit time.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Flow Rate


in hydraulics, the volume of fluid flowing through a cross section of a stream per unit time. The flow rate Q of a fluid for a given cross section ω is determined by the formula

Q = ∫ωu dω

where u is the flow velocity within the limits of d, an elementary segment of the cross section. In steady flow, the flow rate of a dropping liquid is constant along a given stream. The average flow velocity of the fluid can be determined from the known values of the flow rate and cross-sectional area: v = Q/ω. The mass of fluid flowing per unit time through a cross section of the stream is called the mass flow rate M. This rate is related with the volume flow rate by the equation M = ρ Q, where ρ is the density of the fluid. The flow rate of a fluid is measured with water meters, measuring spillways, hydrometers, rate-of-flow meters, and other instruments.


Al’tshul’, A. D., and P. G. Kiselev. Gidravlika i aerodinamika. Moscow, 1965.
Chugaev, R. R. Gidravlika, 2nd ed. Leningrad, 1970.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The minimum methane volumetric flow rate was 60 [m.sup.3]/h, the maximum was 210 [m.sup.3]/h, the average methane concentration was 83%, and the methane extraction time was 1100 days.
Young's modulus of PNCs produced with standard (S), conically shaped (C), short (S_H) and long (L_H) hyperbolically shaped nozzle at a volumetric flow rate of 10 [cm.sup.3] [s.sup.-1] and 100 [cm.sup.3] [s.sup.-1] using (i) MB process and (ii) one-step process.
Liquid 62.92 69.34 67.64 66.42 66.41 72.52 TABLE 6 Low Volumetric Flow Rate Per Ton ([ft.sup.3]/min) Temperature ([degrees]F) (-20/100) R-404A R-407A R-407F R-448A R-449A R-22 Vapor 6.58 7.40 6.87 7.06 7.17 6.31 Liquid 0.072 0.050 0.046 0.051 0.052 0.042 Medium Volumetric Flow Rate Per Ton ([ft.sup.3]/min) Temperature ([degrees]F) (20/100) R-404A R-407A R-407F R-448A R-449A R-22 Vapor 2.65 2.87 2.71 2.81 2.82 2.66 Liquid 0.064 0.046 0.042 0.047 0.048 0.039 TABLE 7 Low Refrigerant Distributor Temperature ([degrees]F) (-20/100) R-404A R-407A R-407F R-448A R-449A Orifice Number 2-1/2 2-1/2 2-1/2 2-1/2 2-1/2 Tube [DELTA]P (psi) 28 22 19 21 22 Nozzle [DELTA]P (psi) 17 13 11 13 13 Dist.
The linear relation between pressure drops and volumetric flow rates in a channel is the Hagen-Poiseuille law, which is typically applicable, even when the flow passes through complex networks in conjunction with the conservation of mass.
[17], he presented the ratio of the volumetric flow rates in eccentric and concentric annuli in terms of the diameter ratio and the eccentricity, for a given pressure gradient.
Comparing the results from DTRT 2 with DTRT 3 (both tests carried out with the same volumetric flow rate), the effects of a larger heat injection rate and temperature level on the borehole thermal resistance are evident.
While volumetric flow rates for the two polymers are identical, mass flows may be dissimilar because of density differences.
All this would be somewhat immaterial if mass and volume were much the same, but measured volumetric flow rates do vary dramatically with temperature and pressure changes.
From such a velocity distribution, the discharge stream was then described in terms of the volumetric flow rate. For the given radial distance, R, a test circular cylinder ([+ or -]15 mm or [+ or -]45 mm in the axial distance, Z, and [+ or -]180[degrees] in the circumferential angle, [THETA]) was centred to the origin in the coordinate system defined in Figure 3.
Using the total slot area or face area and the average slot or face velocity, the authors calculated the volumetric flow rate through the hood ([Q.sub.hood]): [Q.sub.hood] = [V.sub.avg]A.
The flowmeter measures volumetric flow rate by tracking naturally occurring eddies in turbulent pipe flows.

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