the increased viscosity is associated
with a lower initial friction coefficient (during the injection) than
for diesel fuel and was situated at the end of the laminar region
on a Moody diagram. Therefore, during the injection process, the
friction coefficient of the most viscous fuel was lower than diesel,
which allows a slight increase in the amount of fuel injected (see
Fig. 8). Furthermore, the pressure wave from the injection process
was dampened faster because of the higher fuel viscosity, which
translated into higher a friction coefficient in the laminar flow region.
This change in friction coefficient, in turn, increased the pressure
loss and fuel damping characteristic. This complex dynamic is
also a function of the injection system’s geometrical configuration.
Fuels Mu 1–Mu 4 exhibited similar behaviors; their respective viscosities
and associated friction coefficients fell between the extremes
presented in Fig. 8.