1976 Volume 38 Issue 1 Pages 5-12
This paper deals with the comparison of the theoretical discussions (in Ist Report) to some experimental results on the relations between the blowback and the performance of the small two-stroke cycle engines.
In every experiments above mentioned, we measured the pressures in crankcase, scavenging passage, cylinder, inlet and exhaust pipe, the components of gas, CO2, O2, CO, in cylinder, scavenging passage, crankcase and exhaust tank, and investigated the flow in scavenging passage by means of a high-speed photography of the smoke mixed in it.
The conclusions obtained by this investigation and that in Ist Report are mainly as follows.
(1) The best value of charging efficiency is obtained at the appropriate quantity of the blowback.
This charging efficiency in deeply relevant to the performance (mean effective pressure).
(2) The faster becomes the engine speed, the larger becomes the exhaust port height giving the appropriate quantity of the blowback.
Notwithstanding the pipe systems (as inlet, exhaust and scavenging passage) are considered or not, the conditions of (1) and (2) above mentioned are qualitatively realized.
(3) In case of the quantitative judgement of the efficiency, the scavenging passage is regarded not as pipe but as volume.
Futher, in this case, the condition between perfect diffusion and half diffusion is considered better than that of stratification.
It is also considered from the point of view of visibility by means of the high-speed photography.
(4) Even if much quantities of the blowback exist, an abnormal explosion between the blowback (burned) gas and the mixture (gasoline and air) is not produced.
(5) In addition, we also cleared up the influence of inertia-effect and pulsation-effect to delivery ratio.
