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Title: A Polytropic Approximation of Compressible Flow in Pipes With Friction

Abstract

This paper demonstrates the usefulness of treating subsonic Fanno flow (adiabatic flow, with friction, of a perfect gas in a constant-area pipe) as a polytropic process. It is shown that the polytropic model allows an explicit equation for mass flow rate to be developed. The concept of the energy transfer ratio is used to develop a close approximation to the polytropic index. Explicit equations for mass flow rate and net expansion factor in terms of upstream properties and pressure ratio are developed for Fanno and isothermal flows. An approximation for choked flow is also presented. Here, the deviation of the results of this polytropic approximation from the values obtained from a traditional gas dynamics analysis of subsonic Fanno flow is quantified and discussed, and a typical design engineering problem is analyzed using the new method.

Authors:
ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1524879
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Fluids Engineering
Additional Journal Information:
Journal Volume: 141; Journal Issue: 12; Journal ID: ISSN 0098-2202
Publisher:
ASME
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING

Citation Formats

Kirkland, William M. A Polytropic Approximation of Compressible Flow in Pipes With Friction. United States: N. p., 2019. Web. doi:10.1115/1.4043717.
Kirkland, William M. A Polytropic Approximation of Compressible Flow in Pipes With Friction. United States. doi:10.1115/1.4043717.
Kirkland, William M. Fri . "A Polytropic Approximation of Compressible Flow in Pipes With Friction". United States. doi:10.1115/1.4043717.
@article{osti_1524879,
title = {A Polytropic Approximation of Compressible Flow in Pipes With Friction},
author = {Kirkland, William M.},
abstractNote = {This paper demonstrates the usefulness of treating subsonic Fanno flow (adiabatic flow, with friction, of a perfect gas in a constant-area pipe) as a polytropic process. It is shown that the polytropic model allows an explicit equation for mass flow rate to be developed. The concept of the energy transfer ratio is used to develop a close approximation to the polytropic index. Explicit equations for mass flow rate and net expansion factor in terms of upstream properties and pressure ratio are developed for Fanno and isothermal flows. An approximation for choked flow is also presented. Here, the deviation of the results of this polytropic approximation from the values obtained from a traditional gas dynamics analysis of subsonic Fanno flow is quantified and discussed, and a typical design engineering problem is analyzed using the new method.},
doi = {10.1115/1.4043717},
journal = {Journal of Fluids Engineering},
number = 12,
volume = 141,
place = {United States},
year = {2019},
month = {6}
}

Journal Article:
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Works referenced in this record:

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