Effect of Exhaust Pipe Systems upon the Performance Characteristics of a Two-Stroke Diesel Engine : 2nd Report, Influences of the Exhaust Pipe Having Diffusers, Nozzles, Bends or Elbows

Abstract

In the previous paper, the exhaust-pulsation of a UD-3 engine having a simple straight pipe exhaust system was experimented. The apparatus was identical with the one described in the 1st Report. In the present paper, the influences of the exhaust pipe system having diffusers, nozzles, bends or elbows on the performance characteristic are dealt with. Results are as follows. a) In the case of an exhaust pipe with diffusers, the pulsation coefficient for a straight pipe is available with the equivalent length derived from the impedance theory. Only a few percent increase in power was observed in comparison with a straight pipe system in a favorable condition. b) For the nozzle, the pulsation effect can not be expected below an area ratio of 0.3, particularily in the case of a super-charged engine. From the standpoint of an effective exhaust energy, a shorter pipe length is preferable. c) The bend effect has little influence on the performance, judging from the pressure wave observations and the propagation velocity.