APPENDIX L Some “Rules of Thumb” and Trends in Aircraft Propulsion
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| Example: | Takeoff thrust at the standard ambient temperature of 59°F will suffer ∼20% drop at an ambient temperature of 99°F! |
| Solution: | Water or water–alcohol injection in the compressor |
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- Heat absorbed to evaporate the water leads to a lower Δs, higher pressure and density
- Increased mass flow rate is not shown, since the h–s diagram is per unit mass
- Compressor pressure ratio increases as the corrected shaft speed increases with lower temperature
- Latent heat of evaporation of water is higher than alcohol, therefore it takes more alcohol for the same cooling effect.
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At any engine ...
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