Straddle-Mounted Low Pressure Compressor With Split Bearing Support
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently supporting the low pressure compressor section and high pressure compressor section, particularly in terms of bearing support and gear reduction mechanisms, which affect the overall efficiency and thrust generation.
Innovation Solution
A two-spool gas turbine engine design incorporating a planetary gear system for gear reduction, with specific bearing support structures such as first and second low spool support bearings located axially between the low pressure compressor and gear reduction, and axially aft of the low pressure compressor, respectively, to drive the fan section at a slower speed than the low pressure turbine, while the high pressure turbine drives the high pressure compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional bearing support structure is used for the low pressure compressor, then the structure is simple, but the thrust generation efficiency and fuel consumption are insufficient
Solution Approach 1:
The bearing support structure is segmented into multiple functional zones: a first bearing support structure positioned forward of the low pressure compressor and a second bearing support structure positioned aft of the low pressure compressor. This segmentation allows optimized support at different locations, improving thrust generation efficiency while maintaining manageable structural complexity through modular design.
2Use of energy by moving object
If the fan is driven at high speed directly by the low pressure turbine, then the power transmission is simple, but the fan cannot operate at optimal speed for fuel efficiency
Solution Approach 1:
A planetary gear system serves as an intermediary between the low pressure turbine and the fan. The gear system includes a sun gear, planet gears, and a ring gear that together provide speed reduction while allowing the fan to rotate at an optimized speed for fuel efficiency during cruise conditions, decoupling the turbine speed from the fan speed.
3Reliability
If the low spool is unsupported between the low pressure compressor and gear reduction, then the structure is simpler, but the reliability and stability are reduced
Solution Approach 1:
Different bearing support qualities are applied at different locations along the low spool. The first bearing support structure provides support forward of the low pressure compressor, and the second bearing support structure provides support aft of the low pressure compressor. This localized quality approach ensures reliability and stability where needed while avoiding unnecessary complexity in other areas.
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 the efficiency of thrust generation and fuel consumption by optimizing the gear reduction ratio and bearing support, leading to improved performance and reduced fuel consumption, particularly at cruise conditions.
Implementation Method 1
The gear reduction is a planetary gear system. A sun gear is in driving engagement with an input from the low spool. The planetary gear set includes a ring gear fixed from rotating relative to the engine static structure.
Implementation Method 2
A first low spool support bearing is located axially between the low pressure compressor and the gear reduction. A second low spool support bearing is located axially between the low pressure compressor and the high pressure compressor.
Data Source
AI summary
A gas turbine engine includes a fan section including a fan with fan blades. The fan section drives air along a bypass flow path in a bypass duct. A gear reduction is in driving engagement with the fan. The gear reduction is a planetary gear system. A low spool includes a low pressure turbine that drives a low pressure compressor and drives the gear reduction to drive the fan at a speed slower than the low pressure turbine. A high spool includes a high pressure turbine that drives a high pressure compressor. A first low spool support bearing is located axially between the low pressure compressor and the gear reduction. A second low spool support bearing is located axially between the low pressure compressor and the high pressure compressor.