On the effective lenght of the top piston ring involved in hydrodynamic lubrication

This paper describes a simple analytical model for top piston ring lubrication. The model is constructed using the open-end boundary condition hypothesis, with an assumption of rninimum hydrodynamic pressure in the effective ring length equal to the saturation pressure. The analysis confirms that not all of the ring length is involved in the case of hydrodynamic lubrication, and the effective length is found to be less than 40-50% under some operating conditions. The results are in agreement with previous investigations.