Effects of internally charged hydrostatic gas bearing on performance of gas springs in free piston stirling engine

Abstract

The pneumatic supporting system consisting of gas springs and self-charged hydrostatic bearings can suppress vibrations and improve durability of free piston Stirling engines. In this paper, a free piston Stirling generator with pneumatic supporting system on the displacer was developed based on a prototype of plated spring scheme. A series of experiments were carried out to evaluate the impacts of self-charging gas bearing on the performance of gas springs. During the experiments, the linear alternator was applied an external AC power supply and the pressure fluctuations in working chamber were ensured to be consistent so that the pneumatic supporting system was separated from the entire engine. Through blocking the orifices and ducts of gas bearings with plugs, the gas springs were decoupled with the gas bearing. Comparative results show that the internally charged hydrostatic bearing can effectively reduce the mechanical damping of the displacer with a reduction from 117 N/m to 83 N/m after the bearing is switched on. While the hydrostatic bearing has side effects on the gas springs that increase the hysteresis loss from 78.48W to 337.11W and decrease the axial stiffness significantly.

Keywords

• Stirling engine
• Free piston
• Gas spring
• Gas bearing
• Hysteresis loss