The significant reduction of
intake pressure along with the changing valve overlap during the tip-out results in a large increase of internal residual.
Figure 3 shows that in this study the residual gas level ranged from a maximum of 7% at a throttled, 60 kPa
intake pressure condition, to a minimum of 2% at a boosted 146 kPa
intake pressure.
In order to ensure that the test is comparable, an automatic constant-pressure valve is installed onto the intake airline between the mixer and the engine to ensure that
intake pressure is in consistency with that under normal inlet running condition.
This may be due to increase in
intake pressure and temperature of charge entering in to the cylinder along with the steam through inlet manifold.
The
intake pressure is regulated by pressure control unit.
Parameter Description Value 1 Q Cooling capacity 300 W (1023.6 Btu * h-1) 2 n Motor speed 1800 rpm 3 [T.sub.eva] Evaporation 5[degrees]C (41[degrees]F) temperature 4 [T.sub.con] Condensation 46[degrees]C temperature (114.8[degrees]F) 5 [P.sub.in]
Intake pressure 0.35 MPa (50,763 psi) 6 [P.sub.out] Back pressure 1.20 MPa (174,045 psi) Table 2.
That causes an air leak and a loss of
intake pressure. Then the engine doesn't get enough cool air to keep it running smoothly--especially in hot weather.
As the pressure ratio ([p.sub.e]/[p.sub.i]) and the compression ratio are varied, the fraction of the cylinder volume occupied by the residual gas at the
intake pressure varies.
To that effect, the test gun came with a special adapter to limit the
intake pressure to 125 psi.
Sensor input is provided regarding yaw rate, wheel speed, steering angle, throttle position, lateral g forces, and front/rear g forces, as well as the engine rpms,
intake pressure, and transmission gear ratio.
The volume of the manifold's plenum is tuned to resonance together with the length of the inlet passages to amplify
intake pressure waves thereby assisting charge, air filling of each cylinder.