A Study Of Key Structures And Fabrication Technology Of A Micro Turbine Engine

The micro aerocraft with MEMS (Micro Electro Mechanical Systems) technology is one of the most attractively fields of aerospace field. The micromation of power plant is the key technology of micro aerocraft. In recent years, the power MEMS and micro engine have been researched by the foreign countries, especially int the United States. The Silicon etching technology has been successfully applied to the development of micro-engines. The development of micro engine is from two-dimensional structure to complex three-dimensional free-form, from traditional silicon-based MEMS materials to a more high-performance alloy materials. The more micro fabrication technologies are needed for the development micro engine.The principle of micro-turbine engine is analysed. The working peocess and thermal cycling are discussed. To compare the working process with micro-turbine engine and tradition turbine engine, a new distributed structure of micro-turbine engine was developed ccording to the characteristics of micro engine. The combustion chamber and rotor was separated, more than one micro-turbine engine was supplied by one combustion chamber. The design of micro-turbine was simpleness. The heat of mciro combustion chamber is less transferring to the turbineA micro turbine and compressor with micro three-dimensional structures was designed for the better capability. The internal flow of turbine and compressor was analysied by the Computational Fluid Dynamics software. The assembly of micro-turbine is difficult because of the small size. The rotation accuracy and stability of rotor will be reduced. Improving the coaxial accuracy is a key technology. In this paper, an integrated of turbine-shaft-compressor structure was designed. It can reduce component number and improve the stability of rotor. And the joint strength and reliability will increase.The dimension of micro turbine engine is usually only few millimeters, the rolling bearing is not suitable. A new mciro radial dynamic compression gas bearing was designed and and verified the reasonable of this new structure with FLUENT sofaware. According the simulation results, the parameters of gas bearing was optimized.The blade of the turbine and compressor of mciro engine is two- dimensional structure and used with Si-based materials because of the limitation of tradition MEMS technology. Due to the size of micro-turbine engine, it's still difficult to machine free-form structures by traditional MEMS technology. The mciro EDM machining technology has the characteristic of no macroscopic cutting force, simple device and ture three-dimensional process capacity with multifarious materals cantans metal and semiconductor materials. So the micro EDM machining technology is well suitable for the fabrication micro turbine engine with three-dimensional structures.Electrode wear is a major problem of micro-EDM milling. Based on the characteristic of micro-EDM milling, a new compensation with fixed length real time was put forward. A mciro EDM milling CAM system was developed based on the Unigraphics software plant. A mciro chess and face with complex thres- dimensional structure was machined by this CAM system.The key components of mciro turbine engine were fabricated by micro EDM machining technology. A rotation axis was machined by mciro electric discharge grinding; the blade of turbine and compressor with micro three- dimensional structure were machined by mciro EDM milling; the gas bearing was machined by mciro wire electrical discharge machining.The power source was supplied by the external air source. The speed of rotor was reached 4×104RPM. The influence of inlet pressure and distance of inlet nozzle were researched.In this paper, a new micro turbine engine was designed and simulation. The key components of mciro turbine engine were fabricated by micro EDM machining technology. A micro turbine engine protype was realized with high rotation speed, which lays the foundation to realize pratical mciro power engine.