Split Compressor Multi-Spool Engine Reduces SFC
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Solution Overview
Problem
Current gas turbine engines face challenges in reducing specific fuel consumption (SFC) and increasing thermal efficiency, as existing technologies often lead to increased compressor and turbine loading, design complexity, and weight when attempting to enhance pressure ratios, which can deteriorate efficiency and increase costs.
Innovation Solution
A multi-spool gas turbine engine with a split compressor system is introduced, where an extra compression stage is added on the low-pressure spool, allowing for better distribution of compressor work across spools, increasing overall pressure ratio, and enabling the low-pressure compressor to operate at a different speed than the turbine through gear reduction, thereby reducing SFC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If additional compressor and turbine stages are added to increase pressure ratio, then thermal efficiency improves, but device complexity and weight increase
Solution Approach 1:
The compressor system is divided into multiple independent spools (low-pressure spool with first compressor, intermediate-pressure spool with second compressor, high-pressure spool with third compressor) that can operate at different rotational speeds. This segmentation allows each compressor stage to be optimized independently and avoids the complexity of adding stages to a single rigid compressor system.
Solution Approach 2:
The multi-spool architecture enables dynamic operation where each spool rotates at different speeds optimized for its specific pressure ratio range. The low-pressure spool, intermediate-pressure spool, and high-pressure spool can independently adjust their rotational speeds to maintain optimal efficiency across varying engine operating conditions, avoiding the static complexity of fixed additional stages.
2Loss of energy
If pressure ratio is increased to improve thermal efficiency, then SFC decreases, but compressor loading increases and deteriorates efficiency
Solution Approach 1:
The compression process is segmented across three independent spools, each handling a specific pressure ratio range. The low-pressure spool handles the initial compression stage, the intermediate-pressure spool handles the middle stage, and the high-pressure spool handles the final stage. This segmentation prevents any single compressor from being overloaded, maintaining optimal efficiency at each stage while achieving high overall pressure ratio and reduced SFC.
Solution Approach 2:
The system changes the operational parameters of each compressor by allowing them to rotate at different speeds. The low-pressure compressor operates at a lower speed optimized for its pressure ratio, while the high-pressure compressor operates at a higher speed. This parameter optimization ensures each compressor operates within its efficient range, preventing compressor loading deterioration even as overall pressure ratio increases to reduce SFC.
3Use of energy by moving object
If more compression stages are added to increase pressure ratio, then thermal efficiency improves, but engine weight increases
Solution Approach 1:
Instead of adding numerous stages to a single heavy compressor assembly, the compression function is segmented across three lighter spools. Each spool contains fewer compressor stages, reducing the weight of individual components while collectively achieving the required overall pressure ratio for high thermal efficiency. The distributed architecture eliminates the need for a single massive high-pressure compressor.
Solution Approach 2:
The dynamic multi-spool architecture allows each spool to be sized and weighted optimally for its specific function. The low-pressure spool can be lighter since it handles only the initial compression, while the high-pressure spool is optimized for its specific role. This dynamic distribution of compression work across independently sized spools reduces total engine weight compared to a static single-spool design with many heavy stages.
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 reduces specific fuel consumption, maintains efficiency, and lowers engine weight while avoiding the need for additional compressor and turbine stages, thus minimizing costs and design complexity.
Implementation Method 1
a low-pressure compressor (12a) for compressing air to a first discharge pressure
Implementation Method 2
an intermediate-pressure compressor (13a) for compressing air to a second discharge pressure
Implementation Method 3
a high-pressure compressor (14a) for compressing air to a third discharge pressure
Implementation Method 4
a combustor (15) for heating compressed air and fuel
Implementation Method 5
a high-pressure turbine (14b) for extracting energy from hot combustion gases discharged from the combustor (15)
Implementation Method 6
an intermediate-pressure turbine (13b) for extracting energy from hot combustion gases
Implementation Method 7
a low-pressure turbine (12b) for extracting energy from hot combustion gases
Data Source
Figure 1~2
Figure 3
AI summary
A turboprop or turboshaft engine (10) comprises a first spool (12) including a first compressor (12a) drivingly connected to a first turbine (126), the first turbine (126) further drivingly connected to a load (16). The engine (10) comprising a second spool (13) including a second compressor (13a) drivingly connected to a second turbine (13b), the second compressor (13a) fluidly connected to the first compressor (12a) to receive compressed air therefrom. The engine (10) further comprises a third spool (14) including a third compressor (14a) drivingly connected to a third turbine (14b), the third compressor (14a) fluidly connected to the second compressor (13a) to receive compressed air therefrom.