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where is the density of the fluid, is the average velocity in the pipe, is the friction factor from the Moody chart, is the length of the pipe and is the pipe diameter. The chart plots Darcy–Weisbach friction factor against Reynolds number Re for a variety of relative roughnesses, the ratio of the mean height of roughness of the pipe to the ...
The Reynolds number Re is taken to be Re = V D / ν, where V is the mean velocity of fluid flow, D is the pipe diameter, and where ν is the kinematic viscosity μ / ρ, with μ the fluid's Dynamic viscosity, and ρ the fluid's density. The pipe's relative roughness ε / D, where ε is the pipe's effective roughness height and D the pipe ...
where the roughness height ε is scaled to the pipe diameter D. Figure 3. Roughness function B vs. friction Reynolds number R ∗. The data fall on a single trajectory when plotted in this way. The regime R ∗ < 1 is effectively that of smooth pipe flow. For large R ∗, the roughness function B approaches a constant value.
C is a roughness coefficient; R is the hydraulic radius (in ft for US customary units, in m for SI units) S is the slope of the energy line (head loss per length of pipe or h f /L) The equation is similar to the Chézy formula but the exponents have been adjusted to better fit data from typical engineering situations.
From the chart, it is evident that the friction factor is never zero, even for smooth pipes because of some roughness at the microscopic level. The friction factor for laminar flow of Newtonian fluids in round tubes is often taken to be: [4] = [5] [2] where Re is the Reynolds number of the flow.
A2 stainless steel outside the US, in accordance with ISO 3506 for fasteners. [4] 18/8 and 18/10 stainless steel (also written 18-8 and 18-10) in the commercial tableware and fastener industries. SUS304 the Japanese JIS G4303 equivalent grade. 1.4301, the EN 10088 equivalent. [5] 06Cr19Ni10 and ISC S30408, the equivalent in Chinese GB/T 20878 ...
Note that the value of this dimensionless factor depends on the pipe diameter D and the roughness of the pipe surface ε. Furthermore, it varies as well with the flow velocity V and on the physical properties of the fluid (usually cast together into the Reynolds number Re). Thus, the friction loss is not precisely proportional to the flow ...
As can be estimated from weight loss and the density , the wear coefficient can also be expressed as: [2] K = 3 H W P L ρ {\displaystyle K={\frac {3HW}{PL\rho }}} As the standard method uses the total volume loss and the total sliding distance, there is a need to define the net steady-state wear coefficient: