In-Cylinder Velocity Measurements and Analysis in a Briggs and Stratton Engine

Unsteady velocity measurements made near the spark-plug location of an IC engine using a single-component fiber-optic LDV probe are reported. Measurements were made within a motored Briggs and Stratton single-cylinder air-cooled engine at ∼780 RPM. Data obtained was analyzed using Ensemble averaging, High-pass filtering, Wavelet Decomposition (WD), Proper-Orthogonal Decomposition (POD), and Wavelet-decomposition together with Principal Component Analysis (WD/PCA) techniques to determine the unsteady mean velocity and unsteady turbulence variations in such an engine. The results of the analysis are compared to each other. WD/PCA technique recommended for future engine unsteady flow studies was used to determine the cycle-to-cycle variations. Results indicate to large cycle-to-cycle variations in such an engine.