Gas Turbine Core Casing Diameter Optimization
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Solution Overview
Problem
High Overall Pressure Ratio (OPR) and bypass ratio in gas turbine engines lead to a slender core casing geometry, making it susceptible to flexing and distortion, which can result in rotor blade tip rubs and efficiency losses, while increasing stiffness through additional bracing adds weight penalties.
Innovation Solution
A gas turbine engine design with a planetary gear train and a core engine casing diameter ratio to fan diameter within the range of 0.2 to 0.4, ensuring the core engine casing maintains sufficient stiffness to prevent excessive distortion, and employing a method to calculate the core engine casing diameter based on material properties and operational loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the core engine casing diameter is reduced to accommodate high bypass ratio and high OPR designs, then the engine achieves better fuel efficiency and thrust performance, but the core engine casing becomes more susceptible to flexing and distortion
Solution Approach 1:
The patent applies parameter changes by optimizing the core engine casing diameter within a specific range (0.2 to 0.4 times the fan diameter) to achieve the right balance between fuel efficiency and structural stiffness. This quantitative parameter optimization resolves the contradiction by finding the optimal design space where both requirements are satisfied simultaneously.
2Reliability
If additional bracing is added to increase core engine casing stiffness, then rotor blade tip rubs and misalignment are prevented, but engine weight increases
Solution Approach 1:
The patent resolves this contradiction by changing the design parameter from adding structural bracing to optimizing the core engine casing diameter. By selecting the appropriate diameter within the specified range, the casing itself provides sufficient stiffness to prevent rotor blade tip rubs and misalignment without requiring additional bracing, thereby avoiding weight penalties.
3Strength
If the core engine casing diameter is increased to maintain stiffness, then structural integrity is improved, but the engine core becomes longer and thinner, increasing susceptibility to flexing
Solution Approach 1:
The patent resolves this contradiction through precise parameter control by defining the core engine casing diameter as a specific proportion (0.2 to 0.4 times the fan diameter). This parameter relationship ensures that the casing has sufficient structural integrity while maintaining an optimized geometry that prevents excessive length and thinness, thereby avoiding flexing issues.
Data Source
AI summary
A gas turbine engine comprising a planetary gear train, and a core engine casing. The gear train has a ratio of greater than approximately 3.0, with an input to the gear train being operatively connected to the compressor section, and an output from the gear train being operatively connected to the fan. The core engine casing encloses the compressor section and the turbine section. The fan has a diameter F, and the core engine casing has a diameter C. The core engine casing diameter C varies along an axial length of the core engine casing, and a ratio (C/F) of the core engine casing diameter C to the fan diameter F is within the range 0.2<(C/F)<0.4, along an axial length of the core engine casing.