Split Compressor Gas Turbine Engine Electric Motor Drive
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Solution Overview
Problem
Traditional turboprop and turboshaft gas turbine engines with multiple spools face operability challenges due to the dependency of the low-pressure compressor on the low-pressure turbine, limiting independent operation and efficiency, especially in conditions affecting the ratio between turbine and propeller speeds.
Innovation Solution
The low-pressure compressor is directly driven by an electric motor through a gear system within an accessory gearbox, allowing independent operation and modulation of boost pressure, with power sourced from a secondary unit, battery pack, or generator driven by the gas turbine engine, enabling decoupling from the low-pressure turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the low-pressure compressor is driven by the low-pressure turbine through a shared shaft, then the engine structure is simplified, but the low-pressure compressor cannot operate independently at desired regimes
Solution Approach 1:
The drive system is segmented into two independent parts: the low-pressure compressor is decoupled from the low-pressure turbine and driven by a separate electric motor, while the high-pressure spool maintains its traditional turbine-driven configuration. This segmentation allows the low-pressure compressor to operate independently at desired regimes without being constrained by turbine speed ratios.
Solution Approach 2:
The mechanical coupling between the low-pressure turbine and low-pressure compressor via a shared shaft is replaced with an electric motor-driven system. The electric motor provides independent rotational power to the low-pressure compressor, eliminating the mechanical dependency on the low-pressure turbine and enabling flexible operational control.
2Ease of operation
If the low-pressure compressor is driven by the low-pressure turbine, then fewer components are required, but operability challenges arise due to speed ratio constraints
Solution Approach 1:
The mechanical drive system connecting the low-pressure turbine to the low-pressure compressor is replaced with an electric motor-driven system. This substitution eliminates the speed ratio constraints inherent in direct mechanical coupling, allowing the low-pressure compressor to be operated flexibly at any desired speed regime independent of turbine performance.
Solution Approach 2:
The electric motor serves multiple functions: it can drive the low-pressure compressor during normal operation, act as a starter motor for the high-pressure spool, and potentially function as a generator during engine deceleration. This multi-functionality provides operational flexibility while managing system complexity.
3Adaptability or versatility
If an electric motor is introduced to drive the low-pressure compressor independently, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The electric motor is designed with multi-functionality to justify its addition to the system. It can drive the low-pressure compressor independently for optimized performance, serve as a starter for the high-pressure spool, and potentially generate electricity during engine deceleration. This versatility offsets the increased component count by consolidating multiple functions into a single device.
Solution Approach 2:
The electric motor system is integrated with the existing engine architecture by combining it with the high-pressure shaft interface. The same electric motor that drives the low-pressure compressor can also engage with the high-pressure shaft for starting and generation functions, effectively merging multiple system functions into a unified design that minimizes overall complexity.
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 enables independent operation of the low-pressure compressor, allowing for higher pressure ratios, improved specific fuel consumption, lower turbine inlet temperature, and reduced weight, while maintaining a small number of rotors, enhancing engine efficiency and power density.
Implementation Method 1
an electric motor, said electric motor being decoupled from said low pressure turbine and directly or indirectly driving said low pressure compressor
Implementation Method 2
a generator driven by the gas turbine engine
Data Source
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AI summary
A turboprop or turboshaft gas turbine engine (10) includes a low pressure turbine (30) drivingly engaged to an output shaft (46) for driving a rotatable load (22). A low pressure compressor (26) is de-coupled from the low pressure turbine (30), the low pressure compressor (26) and turbine (30) rotating independently from one another. A high pressure compressor (28) is disposed downstream from the low pressure compressor (26) and is in fluid communication therewith to receive pressurized air therefrom. A high pressure turbine (32) is disposed downstream from the high pressure compressor (28) and is drivingly engaged thereto via a high pressure shaft (34). The high pressure turbine (32) is disposed upstream from the low pressure turbine (30) and is in fluid communication therewith. An electric motor (36) receives power from a power source (42), is drivingly engaged to the low pressure compressor (26), and is operable to drive the low pressure compressor (26) independently from the low pressure turbine (30), the high pressure compressor (28) and the high pressure turbine (32).