Question

The friction factor f in a laminar pipe flow was found to be 0.04.the reynolds number of the flow was

Answer 1

Answer: 1600

Explanation:

We know that Darcy Friction factor

f = 64/Re

Re = 64/f

Re = 64/0.04

Re = 1600

Hence, correct answer is 1600

Answer 2

Answer:

The answer is 1600.

Explanation:

The friction factor exists as describing the loss of pressure of a fluid in a pipe due to the interactions between the fluid and the pipe.

$f / 2=\frac{D}{4 \cdot \rho \cdot u_{m}^{2}} \frac{\Delta P_{f}}{L}$

$\mathrm{f} / 2=$ friction factor - fanning

$\mathrm{D}=$ Pipe diameter in $\mathrm{m}$

$\mathrm{u}_{\mathrm{m}}=$mean velocity in $\mathrm{m} / \mathrm{s}$

$\Delta \mathrm{Pf}=$ pressure drop due to friction in $\mathrm{Pa}$

$\mathrm{L}=$length of pipe in $\mathrm{m}$

$\rho=$ specific gravity in $\mathrm{kg} / \mathrm{m} 3$

For laminar flow:

Friction factor $(\mathrm{f})=\frac{64}{\mathrm{R}_{\mathrm{e}}}$

For turbulent flow:

Friction factor $(\mathrm{f})=\frac{0.316}{\left(\mathrm{R}_{\mathrm{e}}\right)^{1 / 4}}$

Given:

Friction factor$(f)=0.04$

$\therefore \mathrm{R}_{\mathrm{e}}=\left(\frac{64}{0.04}\right)=1600$

Essential Points:

$\rightarrow$ Friction factor$=4 \times$Co-efficient of friction

$\rightarrow$ For laminar flow, the friction factor exists directly proportional to the diameter of the pipe.

$\rightarrow$ For turbulent flow, friction factor$\propto(\text { dia of pipe })^{1 / 4}$.

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