抄録
The turbulence of air swirl in the cylinder of a motored engine with a shrouded intake valve was measured with a hot-wire anemometer. In order to determine the turbulence characteristics such as turbulence intensity, integral time scale, etc., the flow velocity data were analyzed by the "stationary time average method" during a time interval of compression TDC±Δt/2. By changing the time interval Δt, different values of turbulence characteristics were obtained. It was made clear that the use of a finite time interval Δt meant the use of a high pass filter with a cut-off frequency of about 1/2(2Δt). As the angular speed of swirl, Ω, increased, the turbulence intensity, (u')v, increased and the integral time scale, (Lt)v, and the micro time scale, (λt)v, decreased. Here, (u')v, (Lt)v and (λt)v are spatial average values in a cylinder. Different correlations between (u')v and Ω were obtained in different intake valves.
