Performance Evaluation of Internal Combustion Engine Under Noise Measurements an Experimental and Analytical Procedure

Nowadays, the technology of internal combustion engines plays an important role, towards the energy consumption, since it is estimated that one third of the consumed fuel is aimed to counterbalance the friction. Special contribution at this issue has the piston ring – liner system and therefore, the finding of friction and minimum lubricant thickness are studied in order to evaluate its performance, in terms of energy consumption, due to friction and the emitted noise. The numerical methodology using computational fluid dynamics (CFD), solving the Navier-Stokes equations, is extended in order to predict the sound pressure level (SPL) of piston movement. Simultaneously, the contribution of the sound pressure level of cranckshaft bearings is examined. The results are matched with experimental measurements of SPL which held at a single cylinder of 4 stroke gasoline Internal Combustion Engine. They were received at Top Dead Center and at the relevant cranckshaft positions, both at thrust and antithrust side and useful conclusions are taken out. Then, the measurements were processed, using the method of wavelets in order to detect the rapid and impulsive phenomenon of piston slap. The most important piston slap events are shown, accordingly to their contribution at total power losses and their spectral content.