Offset Core Gas Turbine Architecture for Fan Shaft Optimization
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Solution Overview
Problem
Conventional gas turbine engines face limitations in size and efficiency due to the need for the core engine components to be built around the fan shaft, restricting the size of the compressor and turbine sections and limiting the overall pressure ratio and operational speeds.
Innovation Solution
The engine design features a gas generating core that is offset and non-parallel to the fan shaft, allowing for a smaller core size and enabling a larger diameter fan shaft, along with a crescent-shaped inlet duct that delivers air to the core, reducing dirt ingestion and optimizing airflow, and optionally includes a second gas generating core for improved efficiency and redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the core engine components are built around the fan shaft, then the structural integrity and power transmission are ensured, but the size of the compressor and turbine sections is restricted
Solution Approach 1:
The engine is divided into two independent gas generating cores, each with its own compressor and turbine sections. This segmentation allows each core to be optimized independently for its specific function, eliminating the constraint of building around a common fan shaft and enabling larger compressor and turbine sections in each core.
Solution Approach 2:
The patent transitions from a single-axis configuration to a multi-dimensional arrangement with two gas generating cores positioned at different locations relative to the fan shaft. This spatial reconfiguration allows the cores to operate independently without being constrained by the fan shaft diameter, effectively increasing the available volume for compressor and turbine sections.
2Reliability
If the core engine is sized to accommodate the fan shaft, then the power transmission is reliable, but the overall pressure ratio and operational speeds are limited
Solution Approach 1:
By segmenting the engine into two independent gas generating cores, each core can achieve higher pressure ratios and operational speeds without being constrained by the fan shaft size. The segmentation allows each core to be optimized for maximum pressure ratio while maintaining reliable power transmission through the shared fan shaft.
Solution Approach 2:
The patent changes the operational parameters by allowing each gas generating core to operate at different speeds and pressure ratios than what would be possible in a single-core configuration. This parameter flexibility enables higher overall pressure ratios while maintaining reliable power transmission through the common fan shaft.
3Force
If a larger diameter fan shaft is used, then the thrust capability is improved, but the core engine components must be redesigned
Solution Approach 1:
The segmentation into two independent gas generating cores allows for a larger diameter fan shaft without requiring complete redesign of the core components. Each core can maintain its original design while the increased fan shaft diameter provides greater thrust capability through the combined output of both cores.
Solution Approach 2:
The common fan shaft serves multiple functions: it transmits power from both gas generating cores, provides structural support, and enables thrust generation. This multi-functionality allows the fan shaft to be designed with a larger diameter for increased thrust while the core components remain optimized for their specific functions.
4Quantity of substance
If the inlet duct extends further radially, then the air delivery to the core is improved, but the dirt ingestion increases
Solution Approach 1:
The inlet duct is positioned at a specific radial location on the fan shaft where it captures sufficient air for the gas generating core while avoiding the outer regions where dirt accumulation is most prevalent. This local positioning optimization balances air delivery requirements with dirt ingestion minimization.
Solution Approach 2:
The patent utilizes the rotational motion of the fan shaft and the centrifugal forces generated during operation to naturally separate dirt particles from the air stream. The inlet duct is positioned and oriented to take advantage of these forces, converting the potentially harmful dirt ingestion problem into a beneficial separation mechanism that protects the core components.
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
This configuration enhances engine efficiency by allowing the core to operate at optimal speeds and ratios without fan speed constraints, reduces dirt ingestion, and enables a more compact engine design with improved thrust and efficiency.
Implementation Method 1
Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow
Implementation Method 2
The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section through a driven shaft
Data Source
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AI summary
A gas turbine engine (20) has a propulsion unit and a gas generating core (28). The propulsion unit includes a fan (24) and a free turbine (42) that is connected to drive the fan (24) about a first axis (X). The gas generating core (28) includes a compressor (30), a combustion section (36) and a gas generating core turbine (34). The compressor (30) and the gas generating core turbine (34) are configured to rotate about a second axis (Y). An inlet duct (46) is configured to deliver air from the fan (24) to the gas generating core (28). The inlet duct (46) has a crescent shaped cross-section near the fan (24).