Abstract
Laminar burning velocity quantifies the speed of propagation of a planar flame into quiescent unburned fuel/air mixture ahead of the flame at a specified pressure and temperature. The objective of this study was to assess the extent to which differences in laminar burning velocity between fuels could be carried through in to the turbulent combustion regime present in an engine.
Tests were performed on a single cylinder spark ignition engine with fixed spark timing. 20 test fuels were blended by adding different aromatic, olefinic and paraffinic components to a reference base fuel. The performance of the test fuel blends were compared with the reference base fuel for accelerations up to 3800 rpm at wide open throttle conditions. In addition, faster burning fuel blends were tested in vehicles sourced from both the US and European markets. Acceleration and steady state power was compared in these vehicles against an appropriate reference fuel. One set of vehicles from the European market was selected because the vehicles were known to not be responsive to fuel octane quality so that the effect of burning velocity could be separated from any influence of fuel octane quality.
In the single cylinder tests the performance benefits provided by the tests fuels components correlated well with the laminar burning velocity of the components added to the fuel. Statistically significant improvements of power and acceleration were seen in vehicles using faster burning formulations.
KEYWORDS – Spark Ignition, Laminar Burning Velocity, Flame Speed, Gasoline, Fuel