Particle image velocimetry (PIV) has been used to study the in-cylinde
r flow within a single-cylinder optical Spark ignition engine. The eng
ine had a standard four-valve pentroof cylinder head geometry, a compr
ession ratio of 10.5:1, and was motored at a crank speed of 1000 rpm.
Double exposed PIV images were recorded from a range of vertical and h
orizontal measurement planes within the engine's glass cylinder. The i
mages were interrogated using digital autocorrelation to give maps of
two-dimensional instantaneous velocity. Successful PIV measurements ha
ve also been made under firing conditions in the unburned gas ahead of
the flame front, with the engine being skip-fired using a propane/air
mixture. The use of PIV for the characterization of realistic in-cyli
nder flow fields under a variety of inhospitable conditions has theref
ore been demonstrated. Limitations in the current technique are briefl
y discussed and methods for overcoming these limitations are described
. (C) 1996 Society of Photo-Optical instrumentation Engineers.