Thermal Bridge Structure for High-Pressure Gas Across Hot-Cold Sections
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Solution Overview
Problem
Turbomachines with large temperature differentials between sections, such as compressor and turbine, face challenges in structural integrity and high-pressure gas containment due to thermal stress and lack of effective sealing, especially under high-pressure conditions.
Innovation Solution
A thermal bridge with a cylindrical body and flanged regions, featuring counterbore recesses and conical fillets, provides a passageway for gas flow while using fasteners and contact sealing lands to manage thermal stress and ensure sealing, made from materials like nickel-based alloys suitable for high-temperature and pressure applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a separate casing part is used to connect cold compression section to hot turbine section, then the turbomachine can operate with large temperature differential, but thermal stress and structural integrity become problematic
Solution Approach 1:
The thermal bridge is divided into distinct regions: a cold-side region, a hot-side region, and an intermediate region. Each region is optimized for its specific thermal environment, allowing the structure to accommodate differential thermal expansion while maintaining overall integrity. The segmentation enables independent thermal management of each section.
Solution Approach 2:
Different portions of the thermal bridge are designed with different properties suited to their local thermal conditions. The cold-side region has properties optimized for low-temperature strength, the hot-side region for high-temperature resistance, and the intermediate region transitions between these properties. This local optimization allows the structure to handle large temperature differentials without compromising overall strength.
2Ease of manufacture
If a simple connection structure is used between sections, then manufacturing is easier, but sealing and containment of high-pressure gas is compromised
Solution Approach 1:
The thermal bridge incorporates pre-formed sealing surfaces and integrated sealing features during manufacturing. The flanges are designed with precise sealing lands and the intermediate region includes built-in sealing structures that are formed as integral parts of the thermal bridge, ensuring reliable sealing before the component is installed and pressurized.
Solution Approach 2:
The thermal bridge utilizes composite construction combining different materials optimized for their specific functions. The structure integrates high-strength alloys for structural integrity with sealing materials and coatings that provide reliable gas containment. This composite approach maintains manufacturing feasibility while ensuring high-pressure sealing reliability.
3Stability of the object's composition
If a rigid connection is used between cold and hot sections, then structural stability is improved, but thermal stress from differential growth exceeds allowable levels
Solution Approach 1:
The thermal bridge incorporates flexible elements and compliant joints that allow for differential thermal expansion between the cold and hot sections. The intermediate region is designed with controlled flexibility that accommodates thermal growth while maintaining structural stability. This dynamic design allows the connection to adapt to thermal changes without developing excessive stress.
Solution Approach 2:
The thermal bridge is specifically designed to accommodate thermal expansion differences between the cold-side and hot-side sections. The intermediate region includes features that allow for controlled expansion and contraction, such as flexible joints or compliant mounting structures, enabling each section to expand or contract independently according to its thermal conditions while maintaining overall structural stability.
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 thermal bridge effectively connects sections with large temperature differentials, reducing thermal stress and ensuring sound containment and sealing of high-pressure gas, enhancing the operational performance of turbomachines by maintaining structural integrity and efficiency.
Implementation Method 1
The conical fillet helps to reduce thermal stress, arising from differential thermal growth, to allowable levels
Implementation Method 2
ensure sound containment and sealing of high-pressure air between the turbomachinery sections
Data Source
AI summary
A thermal bridge forms a connection between a cold side and a hot side that is capable of withstanding a large temperature differential while high-pressure gas (e.g., air) flows between the two sides within an internal passageway. A cold-side region and hot-side region of the thermal bridge may each have a flange with a plurality of holes. The cold-side region may also include a conical fillet with counterbore recesses to provide access to each of the plurality of holes from a low radial position.