HARMONIC BALANCE METHOD USED FOR CALCULATING THE STEADY STATE OSCILLATIONS OF A SIMPLE ONE-CYLINDER COLD ENGINE

A simple piston-constriction-pipe system is analyzed as a first step in the modelling of a “one cylinder cold engine”. For the pipe part it is assumed that linear acoustic theory holds, while the source is modelled as non-linear. The interaction between the non-linear source part in the time domain and the linear system part in the frequency domain is examined. To this end, the forced oscillations of the model are calculated by using the harmonic balance method. The assumptions used in the basic model are discussed and an extended model is presented together with simulations showing the practical difference between the two models.