Effect of Engine Specifications on In-Cylinder Flow Field in a Spark-Ignited Natural Gas Engine
By Yukiyoshi Fukano, Kazuo Tachibana, Shigeo Kida and Toshikazu Kadota
An experimental study was made to investigate the effects of engine specifications on in-cylinder flow field in a spark-ignited natural gas engine. The instantaneous two-dimentional flow field in a single-cylinder visualization engine was measured by using the PTV method over the wide range of piston combustion chamber configuration, top clearance, and nominal swirl ratio. The results showed that swirl is more shifted to the outward radial direction in expansion stroke as piston cavity diameter decreases. In compression stroke, however, the extent of swirl shift is almost constant even if piston cavity diameter varies. Reverse squish is more accelerated than swirl as piston cavity diameter decreases. Smaller piston cavity diameter resulted in larger squish velocity and actual swirl ratio. Top clearance had little effect on flow field. Swirl is more shifted to the outward radial direction in expansion stroke as nominal swirl ratio decreases. Higher nominal swirl ratio resulted in larger actual swirl ratio, while it had little effect on squish velocity.
- Reprinted from Journal of the M.E.S.J., vol.34. No.11 -
Fluctuation Factors On NOx Emission from Medium Speed Diesel Engine
By Hiromi Kondoh, Takahide Kawano, Kazuhiko Masuda, Masanori Saeki and Shuichi Shimomura
This paper describes the influences of fluctuation factors in respect to NOx emissions from medium speed diesel engine. In order to confirm the possible influences of absolute humidity Ha, air temperature Ta and intercooled air temperature Tsc, in an attempt to correct the measured result of NOx, annual NOx data was modified through two cogeneration engines of 220mm and 280mm in bore. The result indicates that the influence degree from the absolute humidity factor is larger than from the other factors. It was found that annual NOx variations could not be eliminated by the correction formula as given by the Technical Code.
Furthermore, the authors conducted the combustion test by controlling the absolute humidity and the temperature of cylinder inlet air in order to confirm the NOx variations in the medium speed single cylinder diesel engine with 200mm in bore. The absolute humidity is controlled by varying the quantity of water injected into the suction port. These findings show a close proximity to the result of research on two cogeneration engines.
- Reprinted from Journal of the M.E.S.J., vol.34, No. 12 -
