摘要：Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this *** properties,particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case,and the results are utilized in preliminary main design parameter *** engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology,Tampere University of Technology,and Lappeenranta University of *** of the contact-free labyrinth seal used in the piston,the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston *** the other hand,the lack of bearing losses,and the lack of losses associated with a crankshaft system and a gearbox,as well as the lack of lubrication oil expenses,compensates this *** a net result,this new motor would perform slightly better than the conventional *** completely oil-free,it is very environmentally friendly,and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.

摘要：Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers.