Gas Turbine Fan-Tied Inducer Section for Flow Stabilization
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Solution Overview
Problem
In gas turbine engines, the low energy air exiting the fan creates a swirling effect that inefficiently feeds air into the low pressure compressor, and the multiple compressor stages in the faster rotating section increase inertia, adversely affecting engine operability.
Innovation Solution
A gas turbine engine design featuring a fan-tied inducer section with a geared architecture, including a sun gear, star gears, and a ring gear, which drives the fan rotor, and additional turbine sections to manage airflow and reduce compressor inertia, along with an inducer stage connected to the fan rotor to stabilize air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If air exits the fan at the root with low energy, then the fan can operate at lower speeds, but a swirling effect occurs that makes it difficult to efficiently feed air into the low pressure compressor
Solution Approach 1:
An inducer section is introduced as an intermediary component between the fan and the low pressure compressor. This inducer section includes inducer blades that receive air from the fan and pre-condition it (reduce swirl, increase axial flow component) before feeding it to the low pressure compressor, thereby resolving the conflict between low fan speed operation and efficient air feeding
2Stress or pressure
If multiple compressor stages are used in the faster rotating compressor section, then compression capability is increased, but inertia in this section increases which adversely affects engine operability
Solution Approach 1:
The compressor is divided into multiple independent sections (inducer section driven by fan, and low pressure compressor section driven by turbine through gear system). This segmentation allows each section to operate at optimally different speeds, with the inducer section rotating slower to reduce inertia while the low pressure compressor can still achieve required compression through its turbine-driven rotation
3Speed
If a geared architecture is used to connect the low shaft to the fan, then the fan can be driven at lower speeds, but the device complexity increases
Solution Approach 1:
The gear system serves multiple functions simultaneously: it provides speed reduction to allow the fan to rotate slower, it enables the inducer section to operate at a different speed than the low pressure compressor, and it allows independent optimization of each component's operating speed. This multi-functionality justifies the added mechanical complexity by delivering multiple performance benefits
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 design improves engine operability by reducing compressor pressure rise, decreasing inertia, and enhancing aerodynamic efficiency by stabilizing air flow and facilitating efficient transition from the fan to the low pressure compressor, resulting in improved thrust and fuel efficiency.
Implementation Method 1
a speed change mechanism (220) coupled between the second shaft and the fan rotor. The speed change mechanism includes a geared architecture
Implementation Method 2
The core inlet stator is positioned axially between the fan blades and the inducer blades... the inducer section serves to efficiently feed the low pressure compressor
Data Source
AI summary
A gas turbine engine includes a first shaft defining an axis of rotation and a second shaft rotatable about the axis of rotation and spaced radially outwardly relative to the first shaft. A speed change mechanism is driven by the second shaft. A fan includes a fan rotor driven by the speed change mechanism such that the fan and the first shaft rotate at a slower speed than the second shaft. At least one inducer stage is positioned aft of the fan and is coupled for rotation with the fan rotor.