Chemical Engineering - Fluid Mechanics - Discussion

Discussion Forum : Fluid Mechanics - Section 1 (Q.No. 7)
7.
The head loss in turbulent flow in a pipe varies
as velocity
as (velocity)2
inversely as the square of diameter
inversely as the velocity
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
11 comments Page 1 of 2.

Kirub said:   6 months ago
Here, hf​ = fD ​L​v2​/Dg.

Where hf​ is the head loss,
fD​ is the Darcy friction factor,
L is the pipe length,
D is the pipe diameter,
v is the average flow velocity,
And g is the gravitational acceleration.
(1)

Abhishek Kumar Singh said:   2 years ago
Head loss is V^2/2g.
(1)

Mandar Mahajan said:   7 years ago
Darcy Weisbach equation use.

Ap = 4flV^2/2D.
(1)

A. Muthuraja said:   7 years ago
Answer B is correct.

Darcy-Weisbach equation, Hf=4fl(V^2)/(2gd) shows that Hf is directly proportional to velocity^2 and f for Turbulent Flow=0.079/Re: Here Re=pvd/μ.

As f is a dimensionless number (Even V term comes in Co-efficient of friction formula), Hf 4flV^2 is correct. We can also refer Dimensional and Model Analysis.

Option A is wrong (Hf is not various with V).
Option B is Correct (Hf is various with V^2).
Option C is Wrong(Hf is not inversely as the square of diameter).
Option D is Wrong (Hf is not inversely as the velocity).
(3)

Avinash kumar said:   7 years ago
One part of erg equation, which is Burke Plummer equation for turbulent gives the relation of head loss is firstly proportional to velocity squared and inversely proportional to diameter.

Riddhi said:   7 years ago
Anyone, Please explain this clearly.

PRASHANT said:   9 years ago
Because head loss is:

HL = (F)X(L/D)X(V2/2g).

Where,

HL = Total Head Loss.

F = Friction factor related to the roughness inside the pipe.

L = Length of the pipe.

D = Diameter of the pipe.

V = Average liquid velocity in the pipe.

2g = Two times the Universal Gravitation Constant (g=32.2 ft/sec).

Muhammad Usman said:   1 decade ago
Friction factor (f) = (g*D*Head loss) / 2*v^2*L.

This is general equation shows head loss is directly proportional to velocity ^2.

Ravinder said:   1 decade ago
h = (4*f*(l/d)*v^2/2).

Vamsivardhan said:   1 decade ago
Pressure drop in a circular pipe in turbulent flow is proportional to velocity raised to the power of 1.7-1.9.


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