Solving the Haaland Equation for Re

  • Thread starter dearmrfantasy
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In summary, the conversation is about using the Haaland equation to determine the Reynold number Re, given the friction factor, absolute roughness, and internal bore diameter. The equation involves basic algebra and the use of inverse log functions. The person is struggling with the first part of the right hand side of the equation and is seeking help.
  • #1
dearmrfantasy
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Homework Statement



Using the Haaland equation shown below, determine the Reynold number Re

Friction factor λ = 0.032mm = 0.000032m
Absolute roughness Ks = 1.5 x 10-6m
Internal bore diameter d= 0.04m

1/√ λ = -1.8log[(6.9/Re) + [(ks/d)/3.7]1.11]

I have tried to solve the above equation but haven't got a clue as I have not been taught to this level. Consequently it's a bit unfair. Someone tried to help me but confused me even more. I do know the answer but need to show how I got the answer.

Any help would be appreciated.
 
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  • #2
It seems a bit surprising you'd be working with an equation like this if you haven't mastered basic algebra yet. Where are you getting stuck?
 
  • #3
vela said:
It seems a bit surprising you'd be working with an equation like this if you haven't mastered basic algebra yet. Where are you getting stuck?

Basic algebra yes but other people are speaking about anti logs? The left hand side of the equation is easy but I am struggling with the first part of the right hand side.

1/√0.032=-1.8log[(6.9/Re)+[( 1.5 x 10-6/0.04)/3.7]1.11]

Any help would be appreciated.
 
  • #4
The inverse of the log function is the exponential function ex.
 
  • #5
Well, more generally, the inverse of the log base n function is the exponential nx. So, logn(nx) = x.
 

What is the Haaland Equation for Re?

The Haaland equation for Re is an empirical equation used to calculate the friction factor in pipe flow. It is used to determine the Reynolds number, which is a dimensionless quantity that describes the ratio of inertial forces to viscous forces in a fluid flow.

How is the Haaland Equation derived?

The Haaland equation is derived from the Colebrook-White equation, which is an implicit equation used to calculate the friction factor in turbulent pipe flow. It is a modification of the more commonly used Darcy-Weisbach equation for calculating pressure drop in pipe flow.

What are the variables in the Haaland Equation?

The variables in the Haaland equation are the Reynolds number (Re), the relative roughness of the pipe (ε/D), and the friction factor (f). Reynolds number is a dimensionless quantity representing the ratio of inertial forces to viscous forces, while relative roughness is the ratio of the average height of roughness elements to the pipe diameter.

What is the significance of solving the Haaland Equation for Re?

Solving the Haaland equation for Re is significant because it allows for the calculation of the friction factor in pipe flow, which is an important parameter in determining the pressure drop in a pipe. This can be used in various applications such as designing pipelines, determining pumping requirements, and analyzing flow in industrial processes.

What are the limitations of the Haaland Equation?

One limitation of the Haaland equation is that it is only applicable for turbulent flow in smooth or slightly rough pipes. It may not accurately predict the friction factor for laminar or highly rough pipe flow. Additionally, it is based on empirical data and may not accurately represent all flow conditions. As such, it should be used with caution and validated with experimental data when possible.

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