Dual-Starter Turbine Spool Control for Faster Engine Starts
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Solution Overview
Problem
Existing gas turbine engines require additional systems for starting due to inefficiencies in compressor operability, leading to longer start times and increased airflow requirements, which can impact aircraft ground operations and efficiency.
Innovation Solution
A propulsion system with a controller that operates a second starter motor on the low pressure shaft to provide torque based on a base LP shaft torque schedule, improving compressor operability and reducing the need for additional sub-systems like bleeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a starter is coupled to the high pressure shaft only, then the engine can be started, but the compressor operability is insufficient leading to longer start times and increased airflow requirements
Solution Approach 1:
The starter system is segmented into two independent components: a first starter coupled to the high pressure shaft and a second starter coupled to the low pressure shaft. This segmentation allows each starter to independently contribute to spool acceleration, improving compressor operability and reducing start time without increasing airflow requirements
Solution Approach 2:
The low pressure shaft acts as an intermediary element that receives torque from the second starter and transmits it to the compressor spool. This intermediary connection enables direct torque application to the low pressure spool, enhancing the starting process efficiency
2Reliability
If additional sub-systems like bleeds are added to improve starting, then compressor operability can be enhanced, but the device complexity increases
Solution Approach 1:
The invention extracts the starting assistance function from complex sub-systems like bleeds and implements it through a simplified second starter motor coupled to the low pressure shaft. This extraction maintains compressor operability while reducing device complexity by eliminating the need for additional bleed systems
Solution Approach 2:
The second starter motor provides self-contained torque assistance to the low pressure shaft, making the system self-sufficient for starting operations without requiring external bleed systems or complex auxiliary mechanisms
3Weight of moving object
If the starter system is simplified, then the weight is reduced, but the compressor operability during start-up deteriorates
Solution Approach 1:
The starter system is divided into two lightweight components (first starter on high pressure shaft, second starter on low pressure shaft) that together provide sufficient torque for reliable starting, achieving weight reduction while maintaining compressor operability
Solution Approach 2:
The invention changes the torque application parameters by applying torque at two different locations (high pressure shaft and low pressure shaft) rather than one location, maintaining effective compressor operability with a reduced overall system weight
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 approach enhances compressor operability, reduces start times, and decreases airflow requirements, resulting in weight savings, improved ground operations, and increased aircraft utilization.
Implementation Method 1
a first starter motor coupled to the HP shaft and configured to provide motive power to spin the HP shaft to start the gas turbine engine
Implementation Method 2
a second starter motor coupled to the LP shaft and configured to provide torque to the LP shaft
Implementation Method 3
The LP compressor compresses air from an air intake
Implementation Method 4
a HP compressor coupled to a HP turbine via a HP shaft
Implementation Method 5
the compressed air received from the compressor is mixed with a fuel and is combusted to create combustion gases
Implementation Method 6
the combustion gases pass across turbine blades of the turbine, thereby driving the turbine blades, and a shaft to which the turbine blades are attached, into rotation
Data Source
AI summary
A propulsion system includes a gas turbine engine includes a low speed spool and a high speed spool. The low speed spool includes a low pressure (LP) compressor coupled to a LP turbine via a LP shaft. The high speed spool comprising includes a high pressure (HP) compressor coupled to a HP turbine via a HP shaft. A first starter motor coupled to the HP shaft and configured to provide motive power to spin the HP shaft to start the gas turbine engine. A second starter motor coupled to the LP shaft and configured to provide torque to the LP shaft. A controller configured to operate on the second starter motor to provide the torque to the LP shaft based on a base LP shaft torque schedule.