Decoupled Gas Turbine Engine Non-Concentric Spool Design
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Solution Overview
Problem
Concentric design of gas turbine engines limits the achievement of high operating pressure ratios while maintaining a small engine core size, and poses challenges in achieving optimal dimensional tolerances, especially in smaller engines due to packaging constraints.
Innovation Solution
A decoupled gas turbine engine design featuring non-concentric high and low spool assemblies with a combustor in between, utilizing turning ducts with annular and bent portions to redirect airflow between compressor and turbine sections, allowing for independent rotation and improved airflow management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a concentric spool design is used, then the engine structure is compact and easy to manufacture, but the operating pressure ratio is limited and the engine core size cannot be reduced further
Solution Approach 1:
The patent transitions from a traditional concentric (co-axial) spool arrangement to a decoupled non-concentric configuration where the high spool and low spool rotate about separate axes. This dimensional repositioning allows the spools to be arranged in a staggered configuration, enabling higher pressure ratios to be achieved within a compact engine core volume by optimizing the spatial distribution of components rather than simply scaling the concentric structure.
Solution Approach 2:
The patent divides the engine into independently rotating high spool and low spool assemblies with separate axes of rotation. This segmentation allows each spool to be optimized independently for its specific function (high spool for compression, low spool for power extraction) while maintaining a compact overall configuration. The independent segmentation enables higher operating pressure ratios without proportionally increasing the engine core size.
2Volume of stationary object
If the engine core size is reduced for compact applications, then packaging space is optimized, but achieving optimal dimensional tolerances becomes difficult
Solution Approach 1:
By segmenting the engine into decoupled high spool and low spool assemblies with separate axes, the patent reduces the interdependence between critical components. Each spool assembly can be manufactured and assembled independently with relaxed tolerance requirements, as the decoupled configuration eliminates the need for precise concentric alignment between multiple rotating components that would be required in a traditional compact concentric design.
3Stress or pressure
If non-concentric spool assemblies are used, then higher operating pressure ratios are achieved and manufacturing tolerances are easier to maintain, but the device complexity increases due to additional turning ducts
Solution Approach 1:
The patent introduces turning ducts as intermediary components that facilitate airflow between the decoupled high spool and low spool assemblies. These ducts act as mediators that redirect and manage the complex airflow paths created by the non-concentric configuration, allowing the system to achieve higher pressure ratios without requiring direct complex interactions between the spool components themselves.
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
Enables higher operating pressure ratios and easier maintenance of manufacturing tolerances in compact engine designs, particularly beneficial for smaller engines and applications like helicopters, by decoupling the traditional concentric spool orientation.
Implementation Method 1
a turning duct disposed between the low and high pressure compressors for re-directing air flowing from the low pressure compressor to the high pressure compressor
Implementation Method 2
a turning duct disposed between the high and low pressure turbines for re-directing air flowing from the high pressure turbine to the low pressure turbine
Implementation Method 3
the combustor is arranged between the HPC and the HPT
Data Source
AI summary
A decoupled gas turbine engine includes a high spool assembly and a low spool assembly each having a rotational axis that are spaced from one-another. The engine further includes a combustor that may have a centerline spaced from the rotational axes of each spool assembly. Turning ducts of the engine are configured to re-direct airflow from one spool assembly to the next and/or between one spool assembly and the combustor.