×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

terminology problem

terminology problem

terminology problem

(OP)
I came across a term "number of inlet velocity heads", it has to do with a pressure drop and I do not quite understand it. Can somebody please explain the meaning of it to me?
m777182

RE: terminology problem

In the Bernoulli equation for incompressible fluids flowing between points 1 and 2:
p1/ρg + V12/2g + z1 = p2/ρg + V22/2g + z2

the first term is called pressure head, and the second term is called velocity head, and is measured in dimensions of height or length. Multiplying it by ρg one gets the dimensions of force per unit area, N/m2, ie, pressure.

The above-given energy balance formula has to be modified for real fluids by adding to the right side a loss of mechanical energy converted to heat due to friction, ΔPf/ρg.

In an horizontal circular conduit (z1=z2) of constant diameter D, the pressure drop between two points separated by a distance L, at constant rate of flow, is totally due to friction, namely
ΔPf prop. to (L/D)(ρV2/2)

I omitted the demonstration of this formula for the sake of simplicity.

ΔPf in pipe fittings is usually given either as the equivalent length of straight pipe, Le, which gives the same pressure drop as the fitting in question, or as a factor, n (number of velocity heads) by which ρV2/2 has to be multiplied to give the pressure drop.

The friction drop due to contractions or enlargements, as for inlets to vessels, are also expressed in this way.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources