Length Scale and Turbulence Intensity Measurements in a Motored Internal Combustion Engine

An advanced high speed hydraulic system consisting of a special ram and hardware digital controller is described with which a hot wire anemometer has been flown across the bore of a motored spark ignition engine. The only access to the engine was a single 3mm diameter hole and thus the engine modifications required for this measurement technique ate minimised. The velocity imposed by the ram system enabled the spatial turbulent structure to be measured with the advantage of an imposed ‘mean flow’, which makes confident analysis of the data possible. Using a novel learning procedure, the required hot wire trajectories can be followed with great accuracy and repeatability. Some results are presented from the engine as well as a simple method for reliable hot wire calibration.