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Pressure Ratio Management model
The pressure ratio management was developed by Matekunas [1983] and is a
computationally efficient method to determine an approximation of the mass
fraction burned trace xb(θ) at every crank angle θ.
The pressure ratio is defined as the ratio of the cylinder pressure from a firing
cycle p(θ) and the corresponding motored cylinder pressure p0(θ):
The pressure ratio is then normalized by its maximum
The PR has unity value before combustion and rises to a final pressure ratio
during combustion and the increase in the final pressure ratio is called the
modified pressure ratio (MPR)
Pressure Ratio Management model
The fractional rise in the PR (normalized with its maximum) may be used as an
estimate of the MFB:
Results:
* Produces traces that are similar to the
mass fraction burned profiles
* The difference between them has
been investigated in [Eriksson, 1999], and
for position PRN(θ)=0.5 the difference
was in the order of 1-2 degrees. This
suggests PRN(θ) can be used as the mass
fraction burned trace xb.