副室付内燃機関における燃焼室内の乱流特性

概要

論文の詳細を見る
Instantaneous velocity of the gas in the main chamber of a prechamber spark ignition engine driven by an electric motor is measured by laser Doppler anemometer (LDA) during compression and expansion strokes. The LDA measurements are made at several locations in the main chamber. The test engine is operated by changing the speed from 600 to 2000 rpm. In previous studies including author's ones, the turbulence is defined as higher frequency component of the velocity above a cut-off frequency, and a frequency spectrum analysis is performed to obtain the mean velocity and turbulence intensity for each cycle. However, it is very difficult to decide the cut-off frequency in the above method which is called cut-off frequency method. Although there are many ideas how to select the cut-off frequency, the unanimous method has not been established. In this paper, a simple method called curve-fitting method, is newly proposed for separating the turbulence from the instantaneous velocity. The proposed method proves to give reasonable results. And by using this method, the changes with time and spatial distributions of mean velocity, turbulence intensity, integral time-scale and integral length-scale in the main chamber of prechamber spark ignition engine are made clear and compared with the results obtained by conventional cut-off frequency method.
東海大学の論文