A Systems Approach to the Torsional Vibration of Multi-Cylinder Reciprocating Engines and Pumps:

The systems approach for the vibration analysis of complex systems requires that the receptances of the sub-systems are available. For the torsional vibration of rotating systems including reciprocating engines and/or pumps it has been the practice to represent the reciprocating mechanism by a constant rotary inertia. This paper describes the derivation of the receptance for such reciprocating mechanisms, which includes the effects of non-constant rotary inertia. It is then shown how the natural frequencies for torsional vibration vary with angular position and how this in turn affects the vibration in the time domain. The significance of the effects indicated by these simulation techniques is then demonstrated by comparing with results obtained from an experimental investigation.