Aircraft Engine Thrust Redistribution for Contrail Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for contrail mitigation in aircraft engines face limitations in efficiency reduction and turbine entry temperature (TET) increases, leading to suboptimal contrail suppression and engine degradation, particularly when redistributing thrust between inboard and outboard engines.
Innovation Solution
A method involving independent reduction of operating efficiency in a subset of gas turbine engines and simultaneous increase in fuel flow to another subset to maintain total thrust, while ensuring equal turbine entry temperature (TET) rise across all engines, using handling bleeds or other efficiency reduction techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If engine operating efficiency is reduced to mitigate contrails, then contrail optical depth is reduced, but turbine entry temperature increases leading to engine degradation
Solution Approach 1:
The patent divides the engine system into multiple independent controllable units (engines, compressor stages, turbine stages) and applies different efficiency reduction strategies to different segments. This allows selective mitigation of contrails from specific engines while managing TET increases across the fleet, resolving the contradiction between contrail reduction and engine protection.
Solution Approach 2:
The patent changes multiple operating parameters simultaneously (fuel-air ratio, compressor bleed rates, turbine inlet temperature) to achieve contrail mitigation while controlling TET increases. By adjusting these parameters in combination rather than relying on a single parameter change, the system reduces contrail optical depth while limiting engine degradation.
2Object-generated harmful factors
If handling bleeds are used to reduce operating efficiency, then contrail mitigation is achieved with standard hardware, but turbine entry temperature increases further due to reduced core air mass flow
Solution Approach 1:
The patent compensates for TET increases caused by handling bleeds by adjusting other operating parameters, particularly fuel-air ratio and turbine stage efficiencies. This multi-parameter adjustment approach counteracts the unwanted TET rise while maintaining the beneficial contrail mitigation effect of the handling bleeds.
Solution Approach 2:
The system monitors TET and other operating parameters in real-time and uses this feedback to dynamically adjust fuel flow and compressor bleed rates. This closed-loop control ensures that TET remains within acceptable limits even when handling bleeds are activated for contrail mitigation.
3Object-generated harmful factors
If thrust is redistributed between inboard and outboard engines to reduce efficiency, then contrail suppression is achieved without specialised equipment, but the extent of efficiency reduction is limited
Solution Approach 1:
The patent applies efficiency reduction measures selectively to specific engine segments (inboard vs. outboard engines, specific compressor or turbine stages) rather than uniformly across all engines. This segmented approach enables greater overall efficiency reduction and more flexible contrail suppression compared to simple thrust redistribution.
Solution Approach 2:
Different parts of the engine system are given different functions or properties - some engines or engine stages are targeted for efficiency reduction while others maintain normal operation. This local differentiation allows the system to achieve greater total efficiency reduction for contrail mitigation while maintaining overall aircraft performance.
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 allows for significant contrail mitigation with minimal engine degradation by evenly distributing the adverse effects of TET increases, optimizing efficiency reduction and reducing contrail optical depth without excessive fuel consumption penalties.
Implementation Method 1
If during this time local RHw exceeds 100%, water vapour can condense onto activated soot particles, coating them with liquid water. Following freezing, further depositional growth is possible as water vapour is deposited as ice onto the contrail particles.
Implementation Method 2
Following freezing, further depositional growth is possible as water vapour is deposited as ice onto the contrail particles.
Implementation Method 3
As the exhaust of an aircraft engine mixes with ambient air, local relative humidity over water (RHw) rises to a maximum before declining to ambient levels.
Data Source
Figure 1~2
Figure 3~5
Figure 4
AI summary
A method of mitigating contrails produced by an aircraft having a set of gas turbine engines (220, 230) comprises the steps of (i) for each engine in a first subset (220) of the engines, reducing the operating efficiency of the engine to produce a reduction in thrust provided by that engine and (ii) for each engine in a second subset (230), increasing the fuel flow to the engine to increase the thrust provided by that engine, the set of at least two gas turbine engines consisting of the first and second subsets. The method provides for contrail mitigation action by means of engine operating efficiency reduction to be directed to a first subset of engines for which contrail mitigation per unit engine operating efficiency reduction is greatest, the resulting reduction in thrust provided by such engines being at least partially compensated by increasing fuel flow to engines of the second subset.