Dual-Impeller Aircraft Compressor Monolithic Design
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Solution Overview
Problem
Aircraft centrifugal compressors face challenges with thermal gradients and hoop stresses, which affect their performance and durability.
Innovation Solution
A dual-impeller compressor design with a first and second impeller secured as a monolithic body, eliminating gaps and using circumferentially distributed conduits to connect the impellers, reducing stress and improving aerodynamic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single centrifugal impeller is used, then the structure is simple, but thermal gradients and hoop stresses reduce durability
Solution Approach 1:
The single impeller is divided into two separate impellers (first and second impellers) with distinct gaspath faces. Each impeller handles a portion of the compression process independently, reducing the thermal and mechanical stress concentration on any single component. The impellers are positioned back-to-back with no gap between them, creating a segmented but integrated structure that improves durability while managing thermal gradients more effectively.
2Ease of manufacture
If gaps are present between impeller components, then manufacturing is easier, but aerodynamic efficiency decreases
Solution Approach 1:
The first and second impellers are merged into a single monolithic body formed from a single piece of material. This eliminates gaps and interfaces between separate components that would otherwise be present in an assembled structure. The merging achieves gapless aerodynamic surfaces for improved efficiency while the monolithic construction itself simplifies manufacturing by eliminating assembly steps and potential misalignment issues.
3Device complexity
If back face of impeller is exposed, then structural design is straightforward, but hoop stress increases
Solution Approach 1:
The first and second impellers are positioned back-to-back with their back faces adjacent to each other, forming a continuous monolithic structure. This merging eliminates the exposed back face of a single impeller, distributing hoop stresses across the entire dual-impeller assembly. The integrated structure provides mutual support, reducing stress concentration on any individual impeller back face.
4Device complexity
If single impeller configuration is used, then device complexity is low, but aerodynamic efficiency is limited
Solution Approach 1:
The compression process is segmented into two separate impeller stages, each with its own gaspath face and blade configuration. This allows for optimized aerodynamic paths in each impeller while maintaining a relatively simple overall structure. The segmented approach enables better flow management and reduced losses compared to a single impeller, improving aerodynamic efficiency without excessive complexity.
Solution Approach 2:
The dual-impeller configuration adds a dimensional aspect to the compression process by utilizing back-to-back positioning with opposite axial directions. This spatial arrangement allows for more efficient use of available space and creates parallel aerodynamic pathways, enhancing overall aerodynamic efficiency while maintaining a compact structure.
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 dual-impeller configuration enhances robustness, reduces stress, and improves aerodynamic efficiency by eliminating back face concerns and reducing hoop stress, leading to increased compressor life and performance.
Implementation Method 1
a dual-impeller rotatable about a central axis, the dual-impeller having: a first impeller having a first inlet and a first outlet located radially outwardly of the first inlet relative to the central axis
Data Source
AI summary
A compressor for an aircraft engine, has: a dual-impeller having: a first impeller having a first inlet and a first outlet located radially outwardly of the first inlet, and a second impeller rotatable with the first impeller, the second impeller having a second inlet and a second outlet located radially outwardly of the second inlet, the first inlet and the second inlet facing opposite axial directions; and first conduits having first conduit inlets and first conduit outlets, the first conduit inlets fluidly connected to the first outlet of the first impeller, the first conduit outlets fluidly connected to the second inlet of the second impeller; and second conduits having second conduits inlets fluidly connected to the second outlet of the second impeller, a second conduit of the second conduits disposed circumferentially between two adjacent first conduits of the first conduits.