Oxidizer molar ratio is defined as the moles of oxidizer divided by the total moles of fuel, oxidizer and propellant. Oxidizer molar ratio will increases as the number of oxidizing electrons in the oxidizer decreases. Hydrogen peroxide, with two oxidizing electrons has a high molar ratio, four fifths when reacting stochiometrically with methane. Diatomic oxygen, with four oxidizing electrons has a low molar ratio, two thirds when reacting stochiometrically with methane.

Oxidizer molar ratios can be calculated easily for stoichiometric mixtures. Oxygen with four oxidizing electrons mixes stoichiometrically with hydrogen with two reducing electrons for an oxidizer molar ratio of two to six ( four plus two ), dividing by their greatest common denominator, a ratio of one to three. Oxygen with four oxidizing electrons mixes stoichiometrically with methane with eight reducing electrons for an oxidizer molar ratio of eight to twelve ( four plus eight ), dividing by their greatest common denominator, a ratio of two to three. Oxygen with four oxidizing electrons mixes stoichiometrically with quadricyclene with thirty six reducing electrons for an oxidizer molar ratio of thirty six to forty ( four plus thirty six ), dividing by their greatest common denominator, a ratio of nine to ten. Given the combustion efficiency, fuel molar, mixture, mixture oxidizer mix, oxidizer molecular, oxidizer propellant mix and propellant molecular the oxidizer molar ratio can be calculated.

relative fuel = 1.0 - mixture
mixture oxidizer mix = 1.0 + mixture

unreacted fuel = 0.0
if ( relative fuel > mixture oxidizer mix ) {
    unreacted fuel = relative fuel - mixture oxidizer mix
}

If the combustion isn't ideal:

if ( combustion efficiency < 1.0 ) {

Then the quadratic equation is used to determine the part of each reactant that combines chemically:

    ratio = 9999999.9
    if ( relative fuel != 0.0 ) {
    ratio = mixture oxidizer mix / relative fuel
    }
    unreactability = 1.0 / ( 1.0 - combustion efficiency )
    a = 2 * unreactability * unreactability
    b = a * ( ratio - 1.0 )
    c = ratio + 1.0
    unreacted = 0.5 / a * ( sqrt( b * b + 4.0 * a * c ) - b )
    unreacted fuel = relative fuel * unreacted
}

relative fuel *= fuel molar
mixture oxidizer mix *= oxidizer mix molar
mixture molar = relative fuel + mixture oxidizer mix
mixture oxidizer mix /= mixture molar
oxidizer mix = oxidizer propellant mix / oxidizer molecular
propellant mix = ( 1.0 - oxidizer propellant mix ) / propellant molecular
total mix = oxidizer mix + propellant mix
oxidizer mix /= total mix

oxidizer molar ratio = oxidizer mix * mixture oxidizer mix
 
 

This is used in bipropellant rocket, tripropellant rocket, pumped rocket and rocket cost.
 
 

Feedback   Free Electronic Nation Home    Rocket   GNU Free Documentation License