Variable Geometry Combustor Soot Emission Control
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Solution Overview
Problem
Current aircraft gas turbine engines with variable geometry combustors face challenges in controlling contrail formation and optical depth, which impact climate and albedo effects.
Innovation Solution
The implementation of a variable geometry combustor system with a control system that adjusts airflow and fuel flow to target soot emissions, based on atmospheric conditions, to modify contrail optical depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If rich-burn, quick-quench, lean-burn (RQL) combustors are used to reduce soot emissions, then soot production is reduced, but contrail optical depth is also reduced, diminishing the desirable albedo effect
Solution Approach 1:
The combustor system dynamically adjusts the fuel-air ratio and quench air flow based on real-time atmospheric conditions (temperature, humidity, pressure) to optimize soot emissions. The system transitions between different combustion modes (rich-burn, quick-quench, lean-burn) as needed, allowing adaptive control of contrail optical depth to maintain desirable albedo effects while minimizing harmful emissions.
Solution Approach 2:
The system changes key combustion parameters including fuel-air ratio, quench air flow rate, and combustion chamber pressure based on atmospheric conditions. By adjusting these parameters, the system can control soot particle formation and contrail optical properties, resolving the contradiction between reducing harmful emissions and maintaining beneficial albedo effects.
2Object-generated harmful factors
If variable geometry airflow arrangement is implemented to control soot emissions, then soot production can be managed, but device complexity increases
Solution Approach 1:
The combustor is divided into distinct functional zones: rich-burn zone, quick-quench zone, and lean-burn zone, each with dedicated fuel injectors and quench ports. This segmentation allows independent control of soot formation and consumption processes, enabling precise management of soot emissions through localized adjustments in each zone.
Solution Approach 2:
The variable geometry airflow arrangement serves multiple functions: it controls fuel-air mixing, regulates quench air flow, adjusts combustion chamber pressure, and influences soot particle dynamics. This multi-functionality reduces the need for separate control systems for each parameter, thereby managing device complexity while achieving comprehensive soot emission control.
3Object-affected harmful factors
If control system adjusts airflow and fuel flow based on atmospheric conditions, then contrail optical depth can be managed, but measurement and control difficulty increases
Solution Approach 1:
The control system continuously monitors atmospheric conditions (temperature, humidity, pressure) and adjusts combustion parameters based on this feedback. Real-time measurements of these parameters feed into the control algorithm, which dynamically optimizes fuel-air ratio and quench air flow to achieve target contrail optical depth while accounting for changing environmental conditions.
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 solution allows for the reduction or increase of contrail optical depth in response to atmospheric conditions, effectively managing the climate impact of contrails.
Implementation Method 1
Initially-dry soot particles become activated by adsorption of oxidised sulphur
Implementation Method 2
Following this, immersion freezing occurs, producing an ice nucleus
Implementation Method 3
Application of the well-established Schmidt-Appleman criterion is indicative of whether a contrail can form
Implementation Method 4
Further depositional growth of the ice crystals may then proceed, in dependence upon the amount of water vapour
Implementation Method 5
If ambient air is not supersaturated with respect to ice, then as the plume continues to mix out, ice mass is lost via sublimation
Data Source
AI summary
A gas turbine engine comprising a variable geometry combustor having fuel injectors, a rich-burn zone, a quick-quench zone, and a lean-burn zone, and further comprising quench ports for admitting quench air to the quick-quench zone; a variable geometry airflow arrangement for the variable geometry combustor, which is configured to vary an airflow through the fuel injectors and/or the quench ports; and a control system configured to control the variable geometry airflow arrangement in dependence upon an airflow delivered to the combustor, a fuel flow to the fuel injectors, and a target index of soot emissions to control the quantity of soot produced by combustion.