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Thermodynamics of Incompressible and Compressible Fluid Flow
- Aerospace Standard
Published June 20, 2011 by SAE International in United States
Downloadable datasets availableAnnotation ability available
The fluid flow treated in this section is isothermal, subsonic, and incompressible. The effects of heat addition, work on the fluid, variation in sonic velocity, and changes in elevation are neglected. An incompressible fluid is one in which a change in pressure causes no resulting change in fluid density. The assumption that liquids are incompressible introduces no appreciable error in calculations, but the assumption that a gas is incompressible introduces an error of a magnitude that is dependent on the fluid velocity and on the loss coefficient of the particular duct section or piece of equipment. Fig. 1A-1 shows the error in pressure drop resulting from assuming that air is incompressible.
With reasonably small loss coefficients and the accuracy that is usually required in most calculations, compressible fluids may be treated as incompressible for velocities less than Mach 0.2. At higher velocities and for large loss coefficients (Kt and 4fL/D), compressible flow analysis should be used.
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Data Sets - Support Documents
|Unnamed Dataset 1|
|Table 1A-1||Table for Unit Conversion Factor for ρ (lb/ft )|
|Table 1A-3||Coordinates for Reynolds Number Nomograph for Gases ( )|
|Table 1A-4||Coordinates for Reynolds Number Nomograph for Liquids ( )|
|Table 1A-5||Angular Displacement Versus Loss Coefficient|
|Table 1A-6||Values of = Constant|
|Table 1A-7||Example of Flow Loss Calculation|
|Table 1B-1||Conversion Factors|
|Table 1B-2||Characteristic Constants for Gases|
|Table 1B-3||Summary of Ideal Gas Equations for Nonflow Processes (for a unit weight of fluid)|
|Table 1B-4||Constants and for Gases, Van der Waals|
|Table 1B-5||Beattie-Bridgeman Constants|
|Table 1B-6||and for Some Common Cases|
|Table 1B-7||Triple Point Data|
|Table 1B-8||Comparison of Perfect and Imperfect Gases|
AC-9 Aircraft Environmental Systems Committee
Furthers the advancement of technology related to the research, design, test and utilization of aircraft environmental and anti-icing/deicing systems. Develops and updates standards, recommended practices, and information reports contributing to the quality, economy, and safety of commercial and military aircraft.
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