Effects of Engine Variables on Turbulence in a Spark-Ignition Engine

Measurements of turbulence within the cylinder of a motored CFR engine were taken with a hot-wire anemometer. Tests were conducted over a range of engine speeds, volumetric efficiencies, and compression ratios with both shrouded and nonshrouded intake valves. Data were processed digitally using both ensemble- and time-averaging techniques. Mean velocities, turbulent intensities, and turbulent micro and integral scales were computed. A nonstationary time-averaged analysis was found to give consistent and physically reasonable results. The turbulence which exists near TDC of compression was found to be isotropic, with both its intensity and scale determined by the intake process.