Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-08-16
SCIENCE DELVES
INTO AUTO WTALS
What Happens When Engine
Is in Operation Is
Studied.
Special Dispatch to The Star.

Special Dispatch to The Star.
DETROIT, August is (NAN.A).-
Modern research has made 1t possible
for scientists to peer into the vitals Of
an automobile engine cylinder and to
observe what happens while it is in
operation. The experiment, which has
been reported before the American
Chemical Society. is credited to the
General Motors research laboratories
here through the work Of Lloyd Withrow
and 7. A. Boyd. These men over a
period of years have specialized in the
investigation Of automobile fuels and
the means Of improving them.
Seek Knock Causes.
Their particular effort has been d.
rected toward ferreting out the causes
Of the elusive knock" or ping" with
which power plants used to be afiiicted
BY means of an ingenious Photographic
apparatus simultaneous flame pictures
and pressure records have been taken of
events during the explosion Of the
charge In the cylinder Of a gasoline
engine.
The flame pictures were taken with q
fast camera through a narrow quartz
window built into the ceiling of the
combustion chamber. The length and
location Of this window were such that
the entire progress Of the flame, start
ing from the spark plug and ending at
the far end of the combustion space,
was made visible to the eye of the
camera.
The photographs in reality were NOV
ing pictures of the flame as it sped
across from the spark plug to the end
Of the combustion chamber, but they
were not movies" in the conventional
sense. In this instance, although the
hlm moved at a constant speed and the
shutter remained open while one COM
plete explosion was recorded, the image
obtained was spread out on the Aim. It
was spread out in such way, however
that 1t was possible to diagram in dis
lance and time the progress Of the hame
across the combustion space.
Pressure Records Taken.
Simultaneous pressure records also
were taken, enabling the research men
Ia match preSsures with corresponding
events in the flame pictures.
Mr.. Withrow and Mr.. Byod. report
that the combined fame and pressure
records have revealed many things that
happen In the gasoline engine.
During normal or non-knocking COM
bustion the time required for the flame
TO travel across the space within the
cylinder while a car is running at 30
miles an hour Is about 1-250th Of q
second.
A knocking explosion differs from
non knocking only in the way the last
portion Of the charge burns
The difference is this: whereas in 3
non-knocking explosion the fame COM
tinues to move at a comparatively con-
slant velocity clear to the end, in q
knocking explosion the latter portion
Of the charge infiames at a much higher
rate than normal
Inflammation Rate.
This rate Of Inflammation" is usually
so high that at the instant of the
knock which comes after ignition the
flame appears simultaneously through
out the whole portion Of the charge
still remaining TO be burned.
The extremely high rate Of inflam-
nation which accompanies the knock,
OF which is the knock, in fact, appar-
entity is due to what is termed auto
ignition" or spontaneous Inflammation
occurring within the latter part Of the
charge. This auto ignition may be
caused by the high temperature induced
there by compression resulting from the
burning OF the portion in the rear.
(Copyright, 1891. By the North American
newspaper Alliance, 1nc.1