DESIGN AND PROTOTYPING OF MICRO CENTRIFUGAL COMPRESSOR FOR ULTRA MICRO GAS TURBINE

摘要

In order to establish the design methodology of a micro centrifugal compressor, which is the most important component of an ultra micro gas turbine unit, a 10 times size of the final target compressor (impeller outer diameter 40mm, corrected rotational speed 220,000 rpm) was prototyped and tested. By the conventional machining, it is possible to make an impeller with 3-dimensional configurations even if the size is getting a little smaller. However, taking the productivity of the target size into account, the 2-dimensional shape was chosen as the first model. The conventional 1D prediction method, CFD and FEM analysis were made for this impeller at the first stage of this study. From these results, it was found that the 10 times model had many difficulties to improve the performance characteristics due to its 2-dimensional configurations. Thus, following to the 10 times model, a 5 times size of the final target model (impeller outer diameter 20mm, corrected rotational speed 500,000 rpm) having fully 3-dimensional shape was designed. In order to check the surface roughness and the shape of blades, the plastic impellers were also manufactured by a rapid prototyping process using a micro stereolithography method. Finally the same impeller was manufactured by aluminum and tested by using a hot test rig at the corrected speed of 250,000 rpm.