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2
Air Flow in Mine Airways
Chapter Outline
2.1 Introduction 17
2.2 Derivation of Basic Fluid Flow Equation 18
2.2.1 Determination of l in Eq. (2.1) 18
2.3 Traditional Equations for Pressure Loss Calculation in Mines 21
2.4 Determination of Mine Airway Friction Factor, K 23
2.4.1 Historical Data on Friction Factors for Mine Airways 23
2.5 Air Flow in Ventilation Duct/Pipes 25
2.6 Shock Losses in Mine Airways 25
2.6.1 Direct Calculation of Shock Loss 26
2.6.2 Shock Losses by Increasing Friction Factor 27
2.6.3 Equivalent Length For Shock Losses 27
2.7 Mine Characteristics Curve 28
2.8 Ventilation Airways in Series/Parallel 30
2.8.1 Airways in Series 30
2.8.2 Airways in Parallel 31
2.9 Calculation of Air Horsepower 33
Problems 33
References 34
2.1 Introduction
The chapter deals with the fundamentals of fluid flow in pipes and mine airways. Basic
pressure loss equation is derived and various ways to estimate the friction factor, l, are
presented. In fully turbulent flow only the degree of roughness determines the friction
factor. However, mine airways are very different from conventional pipes. Atkinson’s
equation is developed further, and a large collection of friction factors from the US and
British coal mines are presented. Mine airways are typically rectangular and also have
a lot of obstructions that cannot be theoretically analyzed. Actual data with experience
alone can yield reliable results. Airflow in ventilation ducts made of steel or fiberglass
are discussed. Shock losses owing to obstructions and changes in airway directions are
also discussed. Total resistance of a mine to airflow, R, is used to create a “character-
istic curve” for the mine. It is useful in determining the correct fan size for the mine (to
be discussed later in the book). The concept of “equivalent orifice” is mathematically
analyzed and used to determine the area of a regulator in a mine airway to restrict the
air flow to a predetermined value. Mine airways change the cross section many times
Advanced Mine Ventilation. https://doi.org/10.1016/B978-0-08-100457-9.00002-X
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