Turbulence Intensity and Spatial Integral Scale During Compression and
Expansion Strokes in a Four-Cycle Reciprocating Engine
A laser homodyne technique is applied to measure turbulence
intensities and spatial scales during compression and expansion
strokes in a non-fired engine. By using this technique, relative fluid
motion in a turbulent flow is detected directly without cyclic
variation biases caused by fluctuation in the main flow. Experiments
are performed at different engine speeds, compression rations, and
induction swirl rations. In no-swirl cases the turbulence field near
the compression end is almost uniform, whereas in swirled cases both
the turbulence intensity and the scale near the cylinder axis are
higher than those in the periphery. In addition, based on the measured
results, the k-epsilon two-equation turbulence model under the
influence of compression is discussed.