The Influence of Compression Ring Clearances on the Blowby in a Diesel Engine

The paper considers the effect of axial and radial clearances of compression rings in the piston grooves on the engine blowby. A mathematical model of piston-rings-cylinder seal, which integrates model of gas flow through the crevices of the RPC seal and model of rings motions in the grooves was used to predict the influence of particular clearances values on the blowby. The results of numerical calculations show that this influence is different for the top and second ring clearances and depends on engine operating conditions (especially rotational speed). The paper also presents some results of experimental research conducted to verify the model. The results of the experiment confirmed the results of the numerical predictions.