Reynolds Number for Gas Formula |
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\( Re_g \;=\; 20,100 \cdot \dfrac{ SG_g \cdot Q }{ d \cdot \eta } \) (Reynolds Number for Gas) \( SG_g \;=\; \dfrac{ Re_g \cdot d \cdot \eta }{ 20,100 \cdot Q }\) \( Q \;=\; \dfrac{ Re_g \cdot d \cdot \eta }{ 20,100 \cdot SG }\) \( d \;=\; \dfrac{ SG_g \cdot Q \cdot 20,100 }{ Re_g \cdot \eta }\) \( \eta \;=\; \dfrac{ SG_g \cdot Q \cdot 20,100 }{ Re_g \cdot d }\) |
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| Symbol | English | Metric |
| \( Re_g \) = Reynolds Number | \( dimensionless \) | \( dimensionless \) |
| \( SG_g \) = Gas Specific Gravity | \( dimensionless \) | \( dimensionless \) |
| \( Q \) = Gas Flow Rate | \(ft^3\;/\;sec\) | \(m^3\;/\;s\) |
| \( d \) = Pipe Inside Diameter | \( in\) | \( mm \) |
| \( \eta \) (Greek symbol eta) = Gas Viscosity | \(lbf - sec\;/\;ft^2\) | \(Pa-s\) |
The Reynolds number, a dimensionless number used in fluid dynamics, including when dealing with gases. It essentially expresses the ratio of inertial forces to viscous forces within a fluid. When applied to gases, this number helps predict the flow's behavior, determining whether it will be laminar (smooth) or turbulent (chaotic). Factors influencing the Reynolds number for a gas include the gas's density, its velocity, a characteristic length (like the diameter of a pipe), and the gas's viscosity. A low Reynolds number indicates viscous forces dominate, leading to laminar flow, while a high Reynolds number signifies inertial forces prevail, resulting in turbulent flow. This concept is vital in various applications, from designing pipelines to understanding aerodynamic forces on aircraft.
