Friction Factor Directly From Roughness Measurements

2001 ◽  
Author(s):  
Elling Sletfjerding ◽  
Jon Steinar Gudmundsson
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Power Spectrum ◽  
Friction Factor ◽  
High Reynolds Number ◽  
Gas Flow ◽  
Relative Roughness ◽  
High Reynolds ◽  
Friction Factor Correlation ◽  
Roughness Measurements

Abstract Pressure drop experiments on natural gas flow in 150 mm pipes at 80 to 120 bar pressure and high Reynolds number were carried out for pipes smooth to rough surfaces. The roughness was measured with an accurate stylus instrument and analyzed using fractal methods. Using a similar approach to that of Nikuradse the measured friction factor was related to the measured roughness values. Taking the value of the relative roughness and dividing it by the slope of the power spectrum of the measured roughness, a greatly improved fit with the measured friction factor was obtained. Indeed, a new friction factor correlation was obtained, but now formulated in terms of direct measurement of roughness.

Friction Factor Directly From Roughness Measurements

2003 ◽  
Vol 125 (2) ◽  
pp. 126-130 ◽  
Author(s):  
Elling Sletfjerding ◽  
Jon Steinar Gudmundsson
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Power Spectrum ◽  
Friction Factor ◽  
High Reynolds Number ◽  
Gas Flow ◽  
Relative Roughness ◽  
High Reynolds ◽  
Friction Factor Correlation ◽  
Roughness Measurements

Pressure drop experiments on natural gas flow in 150 mm pipes at 80 to 120 bar pressure and high Reynolds number were carried out for pipes smooth to rough surfaces. The roughness was measured with an accurate stylus instrument and analyzed using fractal methods. Using a similar approach to that of Nikuradse the measured friction factor was related to the measured roughness values. Taking the value of the relative roughness and dividing it by the slope of the power spectrum of the measured roughness, a greatly improved fit with the measured friction factor was obtained. Indeed, a new friction factor correlation was obtained, but now formulated in terms of direct measurement of roughness.

Friction Factor Comparison Between Mixing Length Theory and Empirical Correlation

2022 ◽  
Author(s):  
M Prasad
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Friction Factor ◽  
High Reynolds Number ◽  
Mathematical Representation ◽  
Mixing Length ◽  
Series Form ◽  
High Reynolds ◽  
Mixing Length Theory ◽  
Grain Roughness

Abstract Equivalent sand grain roughness is required for estimating friction factor for engineering applications from empirical relation via Haalands equation. The real surfaces are different from the sand grain profile. The correlations for friction factor were derived from use of discrete roughness elements with regular shapes such as cones, bars etc. The purpose of the paper is to derive analytical expression of friction factor for a 2 dimensional semi-cylindrical roughness (not exactly a 3 dimensional sand grain but for the circular profile of cross- section) using Navier Stoke equation and mixing length theory. This is compared with the modified series mathematical representation of Haalands equation for friction factor in terms of equivalent sand grain roughness. The comparison is valid for high Reynolds number where the velocity profile is almost flat beyond boundary layer and approximately linear all throughout the boundary layer. The high Reynolds number approximation for Haalands equation is derived and the series form of the friction factor compares approximately with the series form derived from first principles, where in the exponents of the series expansion are close.

Pressure power spectrum in high-Reynolds number wall-bounded flows

2020 ◽  
Vol 84 ◽  
pp. 108620 ◽  
Author(s):  
Haosen H.A. Xu ◽  
Aaron Towne ◽  
Xiang I.A. Yang ◽  
Ivan Marusic
Keyword(s):  
Reynolds Number ◽  
Power Spectrum ◽  
High Reynolds Number ◽  
Wall Bounded Flows ◽  
High Reynolds

G0605 Friction factor for high Reynolds number

2013 ◽  
Vol 2013 (0) ◽  
pp. _G0605-01_-_G0605-02_ ◽  
Author(s):  
Noriyuki FURUICHI ◽  
Yoshiya TERAO
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
High Reynolds Number ◽  
High Reynolds

Pressure Drop in a Pebble Bed Reactor Under High Reynolds Number

2012 ◽  
Vol 180 (2) ◽  
pp. 159-173 ◽  
Author(s):  
Yassin A. Hassan ◽  
Changwoo Kang
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
High Reynolds Number ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
High Reynolds

Drag Reduction of Bamboo and Abaca Fiber Suspensions in Circular Pipe

2013 ◽  
Vol 388 ◽  
pp. 34-39 ◽  
Author(s):  
Gunawan Kapal ◽  
M. Baqi ◽  
S. Fathernas ◽  
Yanuar
Keyword(s):  
Aqueous Solution ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Aqueous Solutions ◽  
Drag Reduction ◽  
High Reynolds Number ◽  
Circular Pipe ◽  
Fiber Suspensions ◽  
Maximum Drag Reduction ◽  
High Reynolds

The drag reduction of dispersions of fibers in aqueous solutions of was studied as a function of concentration with a circular pipe apparatus. Experiments were carried out by measuring the pressure drop. The purpose of this research is to investigate the reduction of pressure drop in a circular pipe with the addition fiber in aqueous solution. Circular pipe with 4 mm of diameter is used in this study. Concentration of bamboo and abaca fibers solutions are 200 ppm and 300 ppm. It was found that fibers solutions give rise to drag reduction in turbulent flow range. Experimental was conducted from low to high Reynolds number up to 55,000. We observed a maximum drag reduction ratio of 7 % at Reynolds number about 35,000 and found that increased by increasing a concentration of fiber solution.

Sign in / Sign up

Export Citation Format

Share Document