Fuel mass fraction

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{{one source |date=March 2024}}

In combustion physics, fuel mass fraction is the ratio of fuel mass flow to the total mass flow of a fuel mixture. If an air flow is fuel free, the fuel mass fraction is zero; in pure fuel without trapped gases, the ratio is unity.{{cite book | last = Kanury | first = a. | title = Introduction to Combustion Phenomena | publisher = Gordon and Breach | location = New York | year = 1975 | pages = 150 | isbn = 0-677-02690-0 }} As fuel is burned in a combustion process, the fuel mass fraction is reduced. The definition reads as

:$Y\_F\; =\; \backslash frac\{m\_F\}\{m\_\{\backslash rm\{tot\}\}\}$

where

• $m\_F$ is the mass of the fuel in the mixture
• $m\_\{\backslash rm\{tot\}\}$ is the total mass of the mixture