[29.] Liu, K., Burluka, A.A., and Sheppard, C.G.W., "Turbulent Flame and Mass Burning Rate
in a Spark Ignition Engine," Fuel 107:202-208, 2013, doi:10.1016/j.fueL2013.01.042.
The two main contributions to the reduction in the in-cylinder conditions (P,T) upon increasing the water fraction in air are changes in mass burning rate (primarily the laminar burning velocity, see eq.1 and 2, ) and thermophysical properties (primarily the heat capacity) of the fuel-air mixture.
Both the reduction in mass burning rate and the increase in heat capacity with increasing water fraction in air reduce the peak pressure and temperature as shown in Fig.6.
However, the mass burning rate
of TEA (0.029 kg/[m.sup.2]-s) is much slower than short chain hydrocarbon fuels such as hexane (0.077 kg/[m.sup.2]-s) and isopentane (0.103 kg/[m.sup.2]-s) .
In the above, [m.sub.a] and [[LAMBDA].sub.0] are, respectively, the mass burning rate
and the mass burning rate
eigenvalue in the adiabatic condition.
Mass burning rate
is calculated by following equation.
The specific mass burning rate
(rate of mass loss per unit area) was calculated from the surface regression rate and the density of the oil.
Mass, composition (equivalence ratio), temperature and mass burning rate
are calculated for every individual spray packet (zone).
To solve the governing equations given above we need to find an expression for the mass burning rate
([dm.sub.b]/dt) that takes into account the operating conditions (e.g.
The difference [m.sub.e] - [m.sub.b] is the mass in the flame brush, Increasing flame brush and the fresh gas density means that this difference should grow during the flame propagation at a constant turbulent mass burning rate
, contrary to Eq.
where the mass burning rate
[dm.sub.b]/dt is achieved from pressure data, the flame area [A.sub.f] is determined over the burnt volume by assuming spherical flame shape and [[rho].sub.u] is the density of the unburnt zone.
The mass burning rate
in a homogeneous SI engine can be defined as,