Hollow UMGT Impeller Layout for Cooling and Rotor Stability
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Solution Overview
Problem
Ultra Micro Gas Turbines (UMGTs) face manufacturing challenges, small-scale heat transfer issues, and rotor-dynamic instabilities due to high rotational speeds, limiting their efficiency and practical implementation as lightweight power sources for portable electronics and Micro Unmanned Aerial Vehicles.
Innovation Solution
A novel UMGT design featuring a single-piece, hollow impeller with integrated compressor, turbine, and generator core, manufactured using additive manufacturing, which reduces thermal conduction, enhances rotor-dynamic stability, and incorporates internal blades for cooling and structural reinforcement, along with aerostatic bearings and magnetic thrust compensation to manage high speeds and axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional manufacturing methods are used for UMGT components, then manufacturing processes are well-established, but manufacturing challenges and precision issues arise at ultra-micro scale
Solution Approach 1:
The patent combines the compressor, turbine, and generator core into a single integrated impeller component manufactured as one piece using additive manufacturing. This merging eliminates multiple assembly steps and reduces cumulative manufacturing errors, achieving high precision at ultra-micro scale while simplifying the manufacturing process.
Solution Approach 2:
The patent employs additive manufacturing technology which fundamentally changes the manufacturing approach from conventional subtractive or formative methods. This parameter change in manufacturing methodology enables precise control of micro-scale dimensions and complex geometries that are impossible to achieve with traditional manufacturing techniques.
2Volume of moving object
If the turbine is positioned close to the compressor to reduce device size, then compactness is improved, but heat transfer from hot turbine to compressor reduces efficiency
Solution Approach 1:
The patent segments the impeller into distinct functional zones - a hot turbine section and a cool compressor section - separated by thermal barriers. This segmentation allows the hot and cold regions to be positioned close together spatially while maintaining thermal independence, thus achieving compactness without sacrificing thermal efficiency.
Solution Approach 2:
The patent applies different thermal properties to different parts of the impeller structure. Thermal barriers are strategically placed in the turbine region to conduct heat away from the compressor, while other regions maintain their original thermal characteristics. This local differentiation of thermal properties enables close proximity of hot and cold components without harmful heat transfer.
3Power
If rotational speed is increased to achieve good efficiency, then power output and efficiency improve, but rotor-dynamic and bearing instabilities occur
Solution Approach 1:
The patent replaces conventional mechanical contact bearings with aerostatic (air) bearings that use a film of compressed air to support the rotor. This substitution eliminates mechanical friction and contact wear, enabling stable operation at very high rotational speeds (up to 500,000 rpm) without the instabilities and wear associated with traditional bearing systems.
Solution Approach 2:
The patent changes the operating parameters by using compressed air at controlled pressure to create a stable air bearing film. This parameter change in the support mechanism allows the rotor to operate stably at extremely high speeds where conventional mechanical bearings would fail due to centrifugal forces and friction.
4Device complexity
If additive manufacturing is used to create single-piece impeller, then manufacturing complexity is reduced, but thermal conduction between turbine and compressor increases
Solution Approach 1:
The patent applies different material properties or structural characteristics to different regions of the single-piece impeller. Thermal barriers are incorporated in specific locations where heat conduction would be problematic, while other regions maintain solid continuous material for structural integrity. This local differentiation resolves the thermal conduction issue within the context of an integrated single-piece design.
Solution Approach 2:
Even within a single-piece additively manufactured impeller, the design segments the thermal pathways by incorporating thermal barriers that break up heat conduction paths between the turbine and compressor sections. This segmentation of thermal flow allows the component to remain structurally integrated while thermally isolated where needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design overcomes manufacturing and thermal challenges, improves rotor-dynamic stability, and enables efficient energy generation at high speeds, making UMGTs viable as lightweight power sources for portable applications.
Implementation Method 1
The internal space of the shell structure providing for a flow of cooling air through the internal space for cooling the turbine region of the impeller
Implementation Method 2
aerostatic bearings and magnetic thrust compensation to manage high speeds and axial forces
Implementation Method 3
magnetic thrust compensation to manage high speeds and axial forces
Data Source
AI summary
A novel structural arrangement for the various components of an Ultra-Micro Gas Turbine Generator, based on a single part impeller element which comprises the compressor, the turbine and the electrical generator core in a single annular structure, produced as a single piece by an additive manufacturing process. The single annular structure has a hollow shell structure, with a supporting structure within in. The internal hollow space of the shell structure provides for a flow of cooling air from the outside through the internal space, for cooling the turbine region of the impeller. This air flow could be assisted by the use of internal blades, which can also serve as the supporting structure to increase the strength of the shell structure. The air flow can either be ejected at the center of the turbine, or can provide a high pressure supply for air bearings of the impeller element.