The effect of connecting-passage diameter on the performance of a compression-ignition engine with a precombustion chamber Page: 4 of 31
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N.A.C.A. Technical Note No. 436 3
As in former tests, the passage used was circular in
cross section. This shape was retained because, when us-
ing a circular passage, there is a minimum change in clear-
ance shape as the area of the passage is increased. How-
ever, there was a change in the passage length/diameter
ratio and radius of flare for each passage diameter test-
ed. The length/diameter ratio varied from approximately
3,3 to 0.6 and the radius of flare varied from 11/32 to
17/32 inch. The compression ratio also varied from 13.2
to 13.7 because the precombustion chamber used was de-
signed to give the standard compression ratio of 13.5 when
using a 9/16-inch diameter connecting passage as in pre-
vious work. The effect of these variations on engine per-
formance was considered to be negligible.
The test equipment (fig. 2) and general test methods
used in these tests were the same as those of reference 1i,
except as specifically noted in this report. The only
change in the standard test conditions is in the consider-
ation of full-load fuel quantity, which in this report is
0.000325 pound per cycle, or that quantity of fuel which
will be completely burned, assuming perfect combustion,
with the amount of air inducted per cycle at 82,5 per cent
volumetric efficiency. Previous publications have used
both fuel quantity per cycle and load fraction as refer-
ence scales so there should be no difficulty in the corre-
lation of this work with that already reported.
For convenience of reference, the standard test con-
ditions are tabulated below:
Engine . . . . . . . . . . . single cylinder, 5 by 7 in.
Engine speed . . . . .. .. ... 1,500 r.p.m.
Fuel , , . . . . . . . Diesel engine fuel, 0.847 specif-
ic gravity, 41 seconds Sa bolt
Universal viscosity at 80 F.
Full-load fuel quantity . . . . . 0.000325 lb. per cycle,
Injection period (at 1,500 r.p.m.) , . . 200 crankshaft.
Injection advance angle (at 1,500 r.p.m.) . . . . . 7.
Spray type . . . , . . , , . . , . . . noncentrifugal.
Nozzle type . . , . single orifice, 0.050-inch diameter.
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Moore, C. S. & Collins, J. H., Jr. The effect of connecting-passage diameter on the performance of a compression-ignition engine with a precombustion chamber, report, November 1932; (https://digital.library.unt.edu/ark:/67531/metadc54109/m1/4/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.