Gas Turbine Intermediate Casing Airflow Homogenization
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Solution Overview
Problem
The current design of intermediate casings for gas turbine engines is inadequate in controlling airflow due to heterogeneity in the aerodynamic profiles of the arms, leading to uneven passage cross sections and increased pressure losses.
Innovation Solution
The intermediate casing features inner and outer radial surfaces with adapted profiles in specific section planes, ensuring that the areas between the arms are uniformly identical, and the radial distances between the surfaces differ, thereby homogenizing the airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the arms of the intermediate casing have heterogeneous aerodynamic profiles with different maximum thicknesses and positions, then the structural requirements and utility passage requirements are met, but the passage cross sections for airflow become heterogeneous causing increased pressure losses
Solution Approach 1:
The patent applies local quality by giving each arm a specific aerodynamic profile tailored to its local requirements for utility passage and structural support, while the radial surfaces are locally adapted to compensate for these variations. Each arm's maximum thickness and position are optimized for its specific function, and the radial surfaces are locally modified to ensure uniform overall passage cross-sections, thereby reducing pressure losses while maintaining necessary structural complexity.
Solution Approach 2:
The patent employs asymmetry by allowing the arms to have different aerodynamic profiles, maximum thicknesses, and positions rather than requiring uniform symmetry. This asymmetric design enables each arm to be optimized for its specific structural and utility requirements, while the radial surfaces are asymmetrically shaped to compensate and achieve uniform overall airflow passages, reducing pressure losses despite the inherent asymmetry of individual components.
2Ease of manufacture
If the radial surfaces are designed with a uniform circular cross section, then the manufacturing is simplified, but the heterogeneity of arm profiles causes heterogeneity in passage cross sections deteriorating aerodynamic quality
Solution Approach 1:
The patent applies local quality by modifying the radial surfaces locally to compensate for the heterogeneity of arm profiles. Instead of maintaining a uniform circular cross-section throughout, the radial surfaces are locally adapted in specific regions where arm thickness variations occur, ensuring that the overall passage cross-sections remain uniform and aerodynamically optimized while maintaining reasonable manufacturing simplicity.
3Ease of operation
If the outer wall is uniformly hollowed at equal distance from leading and trailing edges of arms, then the airflow re-acceleration is avoided, but the design does not account for arms with maximum thickness distant from the mean, causing flow control insufficiency
Solution Approach 1:
The patent applies local quality by adapting the hollowing of the outer wall to the specific characteristics of each arm rather than applying a uniform systematic hollowing. The hollowing depth and position are locally adjusted based on the maximum thickness and position of each individual arm, ensuring proper airflow control for arms with varying profiles while maintaining the objective of avoiding flow re-acceleration.
Data Source
AI summary
An intermediate casing includes an inner wall having an outer surface extending along a longitudinal axis, the outer surface having a first profile in a first plane, an outer wall having an inner surface a second profile in the first plane, and first through fourth arms each extending radially. The outer and inner surfaces and the first and second arms delimit a first cavity, the first cavity having a first area and the outer and inner surfaces being separated by a first distance. The outer and inner surfaces and the third and fourth arms delimit a second cavity, the second cavity having a second area and the outer and inner surfaces being separated by a second distance. The first and second profiles are such that the first area is substantially identical to the second area and the first distance is different from the second distance.