LIQUID PISTON STIRLING ENGINES.

Abstract

Some of the characteristics of the liquid piston engine are discussed and attention is drawn to some of the effects observed in these machines that are not present or are less important in other free-piston Stirling engines. In the Fluidyne liquid piston Stirling engine, both the displacer and the piston are liquid. If the displacer column is set into oscillation in its U-tube, the gas above the liquid surface is transferred back and forth between the hot and cold spaces. The resulting pressure variation acts on the liquid in the output column, causing it to move also. The pressure variations do not, however, have any effect on the displacer for they act equally on both ends of the displacer column. If the displacer were left to itself, therefore, the oscillations in the displacer tube would eventually die away because of viscous friction and other losses. Several means for feeding back energy from the power piston to the displacer in order to overcome these losses are discussed. Several examples of such engines are presented and their possible applications considered.