Minor losses in pipe flow explained

Minor losses in pipe flow are a major part in calculating the flow, pressure, or energy reduction in piping systems. Liquid moving through pipes carries momentum and energy due to the forces acting upon it such as pressure and gravity. Just as certain aspects of the system can increase the fluids energy, there are components of the system that act against the fluid and reduce its energy, velocity, or momentum. Friction and minor losses in pipes are major contributing factors.^{[1] [2] [3] [4]}

Friction Losses

Before being able to use the minor head losses in an equation, the losses in the system due to friction must also be calculated.

Equation for friction losses:

H _{Lf} = {v ^{2\over} gR _{h}(\sum} _{i} L _{i} )f ^[5] H _{Lf} = Frictional head lossv = Downstream velocityg = Gravity of EarthR _{h} = Hydraulic radius\sum _{i} L _{i} =Total length of pipingf = Fanning friction factor

Total Head Loss

After both minor losses and friction losses have been calculated, these values can be summed to find the total head loss.

Equation for total head loss,

H _{L} , can be simplified and rewritten as:H _{L} = {v ^{2\over} 2 gR _{h}[(2\sum} _{i} L _{i} )f + R _{h(\sum} _{i} e _{v,i} )] H _{L} = Frictional head lossv = Downstream velocityg = Gravity of EarthR _{h} = Hydraulic radius\sum _{i} L _{i} =Total length of pipingf = Fanning friction factor\sum _{i} e _{v,i} = Sum of all kinetic energy factors in system

Once calculated, the total head loss can be used to solve the Bernoulli Equation and find unknown values of the system.

See also

• Hydraulic head
• Total dynamic head

Notes

1. Web site: Losses in Pipes. my.me.queensu.ca. en. 23 January 2017.
2. Web site: Minor Losses. Anderson. Gunther. Ryan Barr. Risa Benvega. 23 January 2017.
3. Web site: Head Loss in Piping Systems - TechInfo. www.hydromatic.com. 2017-01-22.
4. Web site: Objectives_template. nptel.ac.in. 23 January 2017.
5. Book: Transport phenomena. 2007. Wiley. 978-0-470-11539-8. Rev. 2.. New York [u.a.]. Lightfoot. R. Byron Bird; Warren Stewart; Edwin N..