Design and Simulation of Two Stroke Engines

Design and Simulation of Two-Stroke Engines
Pressure wave reflection (in pipes) (continued)
outflow from a cylinder (continued)
temperature-entropy diagrams, 128-129
at restrictions between differing pipe areas
introduction, 108
First Law of Thermodynamics, application of,
110-112
flow momentum equation, 111, 112
gas properties (functions of), 109
mass flow continuity equation, 110, 111
numerical examples, 113-114
particle flow regimes (diagram of), 109
reference state conditions, 109
sonic particle velocity, solution for, 112-113
temperature-entropy curves for, 108-109
at sudden area changes
introduction, 97
Benson "constant pressure" criterion, 98-99
energy flow diagram, 98
examples: enlargements and contractions,
100-101
nomenclature, consistency of, 98
in tapered pipes
introduction, 124-126
dimensions and flow diagram, 125
gas particle Mach number, importance of, 127
separation of flow (from walls), 126-127
Pressure wave superposition (oppositely moving,
in pipes)
introduction, 69
mass flow rate
directional conventions for, 73-74
numerical values of, 74
supersonic particle velocity
Mach number (defined), 74-75
numerical values for, 77
Rankine-Hugoniot equations (combined
shock/reflection), 76-77
superposition Mach number (determination
of), 75-76
weak shock concept (for modeling unsteady
gas flow), 75, 77
wave propagation
acoustic, propagation velocities (numerical
values for), 73
acoustic velocity, sign conventions for, 73
propagation velocities, sign conventions for,
73
612
"wave interference during superposition" effect,
73
wave superposition
acoustic velocities, local, 69
particle velocity, absolute, 70
particle/propagation velocities, sign conventions
for, 69, 71
particle/propagation velocities (individual
wavetop), 69
pressure-time data, experimental (interpretation
of), 71-72
simplified pressure diagram, 70
superposition particle velocity (analytical),
70-71
superposition particle velocity (experimental),
71-72
superposition pressure ratio, 71
Propagation/particle velocity (acoustic waves)
pressure ratio, 54
specific heats ratio (for air), 54
velocity in air (after Earnshaw), 54
Propagation/particle velocity (finite amplitude
waves in free air)
particle velocity
absolute pressure (p), 55
gas constant (for air), 55
gas particle velocity (for air), 55, 57
pressure amplitude ratio, 55
pressure ratio, 55
specific heat (constant pressure/volume), 55
specific heat ratio, functions of (for air), 56
specific heats ratio, 55
propagation velocity
absolute propagation velocity, 57-58
acoustic velocity, 57
density, 57
isentropic change of state, 57
Propagation/particle velocity (finite amplitude
waves in pipes)
basic parameters (values in air)
particle velocity, 58
pressure amplitude ratio, 58
propagation velocity, 58
reference acoustic velocity, 58, 59
reference density, 59
the compression wave
absolute pressure, 59
density, 60