Design and Simulation of Two Stroke Engines

Exhaust systems (continued)
untuned systems (compact industrial)
discussion, 371
dimensions of (chainsaw), 372
untuned systems (empirical design of), 435
introduction, 435
downpipe diameter vs. exhaust port area, 435,
436
downpipe length, determination of, 436-437
silencer box, placement of, 435
silencer box volume vs. swept volume,
436-437
see also Intake systems; Noise reduction/noise
emission; Silencers/silencing
Exhaust timing control valves. See Control valves
FID (flame ionization detector) analysis
of exhaust emissions, 40-41
First Law of Thermodynamics
First Law, defined, 93
and expansion wave inflow (at a bellmouth),
93-94
in GPB engine simulation model
heat transfer along duct (during time step),
156-158, 160
heat transfer in cylinders and plenums (during
time step), 163-165
mass/energy transport after time stop,
156-158, 160
open cycle flow through a cylinder, 163-164
and moving shock waves (in unsteady gas flow),
202
in pressure wave reflections
at branches in a pipe, 120-121
at contractions in pipes, 106, 107
expansion wave reflection at plain end, 95
at expansions in pipe area, 102, 104
at inflow from a cylinder, 138, 139
at outflow from cylinder, 130-131, 132
at restrictions between differing pipe area,
110-112
see also Heat transfer
Flame velocity
flame front propagation velocity, 283-284
one-dimensional model (discussion), 322-323
and squish action (loop-scavenged, QUB), 331,
333
601
Hying Squirrel machines, 1
Four-stroking
and active radical (AR) combustion, 285
from inadequate scavenging, 218, 285
and liquid gasoline fuel injection, 513
skip-firing, hydrocarbon emissions from, 471
and stratified-charge combustion, 288
Friction/friction losses
bearings
compression-ignition engines with plain bearings,
379
SI engines with plain bearings, 379
SI engines with rolling-element bearings,
378-379
chainsaw engine simulation
introduction and discussion, 380
friction mep (defined), 378-379
friction mep vs. rpm, 383-384
mechanical efficiency vs. rpm, 384
pumping mep vs. rpm, 383-384
compression-ignition engines
with plain bearings, 379
friction and pumping losses (defined)
friction mep, 38, 378-379
pumping loss, 37-38
in GPB engine simulation model, 151
in pressure wave propagation
frictional heat release, 82-83
see also Pressure waves in pipes (friction loss
during)
Fuel consumption/fuel economy
introduction and discussion, 463-464
brake specific fuel consumption
defined, 37
AFR, effect of (chainsaw engine), 479-481
AFR, effect of (low emissions engine),
487-488
AFR, effect of (QUB 400 engine), 472, 474,
476
Batoni map for (Vespa motor scooter engine),
476-477
effect of Asvx on, 427-430
indicated specific, defined, 35
Institut Francais du Petrole stratified charging
engine, 505, 508
in liquid gasoline injected engines, 513-514
in Piaggio stratified charging engine, 501-502