Measurement and Evaluation of Tumble Flow of SI Engine Using Stereo PIV in a Steady Flow Bench (1) Experimental System and Calibration

To evaluate the tumble flow of an SI engine in a steady-flow device, the three-dimensional velocity distribution within the cylinder was measured. For this purpose, a 3D particle image velocimetery using the angular displacement method was constructed. After calibrating the distorted image using a calibration plate, the mapping function was extracted to obtain a 3D velocity distribution. The results were verified by comparing the three-dimensional distribution obtained in this way with the speed measured using a two-dimensional particle image velocimetery. As a result of the verification, a fairly reliable three-dimensional velocity distribution was obtained through appropriate correction and optical system arrangement. However, problems arose in measuring velocity near walls because the scattered light from the incident laser could not be completely removed due to the inclined camera angle.