ANALYSIS ON THE CLEARANCE SEALS LEAKAGE CHARACTER IN FREE PISTON STIRLING ENGINES

Clearance seal technology is seen as a key technology of free piston Stirling engines.It avoids friction loss,needs no lubrication and makes large progress for improving performances of the free Stirling engines.A kind of one-dimensional laminar model with bilateral movement of seal gap for free piston Stirling engines is established and combined with Schmidt isothermal analysis to get mass leakage rate and mass leakage per cycle of a 100W free piston Stirling engines.Meanwhile,different seal gap widths are compared in order to study the impact from the seal leakage and a largest seal gap width allowed is got.Two-dimensional model of seal gap with the import and export for free piston Stirling engines is also established to get more precise mass leakage.Numerical simulation method is used to compute this two-dimensional model and get a similar mass leakage rate.Because of the influence of the import and export of seal gap,the numerical simulation results slightly lower than the results computed by one-dimensional laminar model.