Crank Angle Resolved HC-Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed 961927
In order to separate the HC-emissions from two-stroke engines into short-circuit losses and emissions due to incomplete combustion, Laser Induced Fluorescence (LIF) measurements were performed on the exhaust gases just outside the exhaust ports of two engines of different designs.
The difference between the two engines was the design of the transfer channels. One engine had “finger” transfer channels and one had “cup handle” transfer channels. Apart from that they were similar. The engine with “finger” transfer channels was earlier known to give more short-circuiting losses than the other engine, and that behavior was confirmed by these measurements.
Generally, the results show that the emission of hydrocarbons has two peaks, one just after exhaust port opening and one late in the scavenging phase.
The spectral information shows differences between the two peaks and it can be concluded that the latter peak is due to short-circuiting and the earlier due to incomplete combustion.
The flow outside the exhaust port was measured with Laser Doppler Velocimetry (LDV). These measurements confirm the occurrence of two emission peaks.
Citation: Andersson, Ö., Juhlin, G., Ekenberg, M., Johansson, B. et al., "Crank Angle Resolved HC-Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed," SAE Technical Paper 961927, 1996, https://doi.org/10.4271/961927. Download Citation
Öivind Andersson, Greger Juhlin, Martin Ekenberg, Bengt Johansson, Marcus Aldén
Lund Institute of Technology
1996 SAE International Fall Fuels and Lubricants Meeting and Exhibition
Diagnostics and Modeling in SI Engines-SP-1212, Two-Stroke Engines-PT-69, SAE 1996 Transactions - Journal of Engines-V105-3