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8-Gravel
November 4, 2018
Question

Pressure drop in sharp bend

  • November 4, 2018
  • 3 replies
  • 2790 views

Hi!
I was wondering if someone can point me in the right direction.

Suppose you have a cylinder with a center drilled hole, at the end of the hole a perpendicular hole is drilled through the cylinder wall as shown below:
Sharp bend.png

How can i calculate the pressure drop if the fluid flows from left to right.

 

The fluid is turbulent

 

Regards 
Sigurd

3 replies

23-Emerald I
November 4, 2018

@snã¦ss wrote:

Hi!
I was wondering if someone can point me in the right direction.

Suppose you have a cylinder with a center drilled hole, at the end of the hole a perpendicular hole is drilled through the cylinder wall as shown below:
Sharp bend.png

How can i calculate the pressure drop if the fluid flows from left to right.

 

The fluid is turbulent

 

Regards 
Sigurd


People have been trying to solve this (with accuracy) for a long time.  A good finite element model, properly set up, will come close. There are numerous handbooks (Crane Company used to put out a really good one) that can assist an empirical estimate. 

 

There are a lot of variables:  hole diameter, lengths, effective radius of the turn, Reynolds Number, etc.  The sharp turn at the end is the major problem.

21-Topaz II
November 4, 2018

Hi

 

https://www.youtube.com/watch?v=26TG3SxsHwM
http://www.metropumps.com/ResourcesFrictionLossData.pdf

 

The first is theory behind pipe loss coefficient.

Second is experimental values of coefficient including mitred bends

 

Cheers

Terry

16-Pearl
November 4, 2018

In order of preference:

a.) experiments

b.) CFD

c.) Equations.  

d.) Tabulated loss parameters (k-factors or minor losses)

 

C & D are easiest.

 

For C here's one example that I'll assume has something close to your problem. (Idel'chik)

https://www.nrc.gov/docs/ML1220/ML12209A041.pdf  

 

Crane Technical Paper 410 is good, as Fred points out - but not free.  Any fluids book should have some minor loss factors to get you going.

23-Emerald I
November 6, 2018

A careful web search can reveal a pdf of Crane TP 410