Experimental Assessment of Scavenging Efficiency of Two-Stroke Cycle Engines

Engineers dealing with the two-stroke cycle engine have always sought to find a scavenge flow simulation process which will allow for the development of an existing engine or provide information for the design of a new power unit. Many schemes put forward have been found wanting in some manner, although in recent times the method proposed by Jante has been shown to be very effective and to that end this paper provides further evidence. In this publication a new version of the old idea of simulating scavenging by a liquid flow approach is presented, an apparatus described and test results given for six cylinders of one two-stroke cycle engine. These six test cylinders have dissimilar scavenge flow characteristics while retaining similar dynamic flow parameters and are tested under firing conditions for the usual performance characteristics as well as for scavenging and trapping efficiencies; they are also tested using the Jante motoring method for their scavenge flow behaviour. Finally, the paper discusses the results achieved by the two simulation experimental techniques by comparison with the reality of the actual firing performance data and concludes that the Jante technique is further vindicated and that the new liquid flow test technique shows great promise as a method, particularly for the development of new cylinder designs.