Contrail Mapping Using Engine Efficiency and Humidity Thresholds
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Solution Overview
Problem
Current methods for determining contrail formation and persistence in aircraft engines are inaccurate due to neglecting additional energy flows and exhaust plume temperature changes, leading to poor alignment with physics-based models and reduced accuracy in contrail formation maps.
Innovation Solution
A computer-implemented method that determines a contrail engine efficiency parameter (noverall_λ) accounting for additional energy flows and exhaust plume temperature scaling, generating an improved Schmidt-Appleman equation to calculate the minimum humidity required for contrail formation and persistence, using engine performance model parameters and energy flow parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional Schmidt-Appleman equation is used for contrail formation determination, then the method is simple to implement, but the accuracy of contrail formation maps is reduced due to neglecting additional energy flows and exhaust plume temperature changes
Solution Approach 1:
The patent modifies the traditional Schmidt-Appleman equation by introducing a new parameter λ (lambda) that represents the ratio of actual exhaust plume temperature to the temperature predicted by the traditional equation. This parameter change allows the equation to account for additional energy flows and exhaust plume temperature changes while maintaining the overall structure and simplicity of the original equation. The modified equation becomes: LHV·EI_H2O·(1-ηoverall)/Cp = (Tp/E - Tamb)/G·λ, where λ corrects for the neglected energy flows.
2Measurement precision
If additional energy flows and exhaust plume temperature scaling are accounted for, then contrail formation accuracy is improved, but the computational complexity increases
Solution Approach 1:
The patent applies partial action by introducing a scaling factor λ that partially adjusts for additional energy flows rather than calculating all energy flows in full detail. This approach provides sufficient correction for improved accuracy without requiring complete and complex energy flow calculations. The scaling factor λ is determined through comparison with physics-based models and can be applied as a simple multiplicative correction term, reducing computational requirements while maintaining improved precision.
3Reliability
If physics-based models are used for contrail formation analysis, then the alignment with physical reality is improved, but the ease of operation is reduced due to complex calculations
Solution Approach 1:
The patent introduces the scaling factor λ as an intermediary between the simple Schmidt-Appleman equation and complex physics-based models. This intermediary parameter captures the essential effects of additional energy flows and exhaust plume temperature changes that are present in physics-based models, allowing the equation to align with physical reality without requiring the full complexity of those models. The scaling factor acts as a bridge that translates complex physical phenomena into a simple correction term.
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
The method provides more precise and accurate contrail formation and persistence maps, enabling targeted mitigation of contrail production by identifying specific aircraft operations contributing most to climate warming.
Implementation Method 1
Contrails form when exhaust gases locally exceed the water saturation limit while mixing and cooling to ambient conditions
Implementation Method 2
determining an improved mixing line slope based on the improved Schmidt-Appleman equation (Gλ)
Data Source
Figure 1~2
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AI summary
A computer system (1200) includes a processor (1210) controls the computer system (1200) to perform a computer-implemented method of determining a minimum humidity required for formation and persistence of contrails produced by an engine of an aircraft. The computer-implemented method includes determining engine performance model parameters of the engine at desired operating conditions with zero humidity; determining additional energy flow out of the engine; and determining an exhaust plume temperature scaling factor. The method further comprises determining a contrail engine efficiency parameter (noverall_λ) based on additional energy flow out of the engine and the exhaust plume temperature scaling factor; and generating an improved Schmidt-Appleman equation based on the contrail engine efficiency parameter (noverall_λ). The method further includes determining an improved mixing line slope based on the improved Schmidt-Appleman equation; and determining the minimum humidity required for formation and persistence of contrails produced by the engine based on the improved mixing line slope.