Aircraft Fuel Nozzle Subset Control for Alternative Fuels
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Solution Overview
Problem
The aviation industry faces challenges in operating gas turbine engines efficiently with fuels other than traditional kerosene-based jet fuels, requiring adjustments in fuel properties and operating methods to optimize performance and reduce emissions.
Innovation Solution
A method for operating a gas turbine engine with a combustor featuring a plurality of fuel spray nozzles, including a first and second subset, where the first subset receives more fuel, and a fuel distribution system that provides fuel with a calorific value of at least 43.5 MJ/kg, along with fuel-oil heat exchangers to raise the fuel temperature to 135°C and transfer heat to lower viscosity, optimizing combustion efficiency while minimizing coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fuel temperature is increased to improve combustion efficiency, then combustion efficiency is improved, but coking levels increase
Solution Approach 1:
The fuel spray nozzles are divided into two subsets: a first subset that receives heated fuel (improving combustion efficiency) and a second subset that receives cooler fuel (reducing coking). This segmentation allows different portions of the fuel injection system to operate under different temperature conditions, simultaneously achieving improved combustion while controlling coking.
Solution Approach 2:
Different subsets of fuel spray nozzles are provided with different fuel temperatures according to their specific operational requirements. The first subset operates with heated fuel for optimal combustion, while the second subset receives cooler fuel to minimize coking, creating local quality variations in the fuel distribution system.
2Loss of energy
If fuel with higher calorific value is used to reduce fuel burn rate, then fuel consumption is reduced, but fuel properties require adjustment for optimal performance
Solution Approach 1:
The invention adjusts fuel temperature as a physical parameter to optimize the performance of higher calorific value fuels. By heating the fuel before injection, the system maximizes the energy content utilization of alternative fuels, ensuring they perform optimally in the combustor despite having different chemical properties from traditional jet A-1 fuel.
Solution Approach 2:
The fuel is pre-heated in heat exchangers before reaching the combustor, preparing it in advance for optimal combustion. This preliminary thermal treatment ensures that alternative fuels with higher calorific values are properly conditioned to achieve maximum energy release while maintaining system reliability.
3Use of energy by moving object
If more fuel is supplied to certain nozzle subsets to optimize combustion, then combustion efficiency is improved, but fuel distribution complexity increases
Solution Approach 1:
The fuel distribution system is segmented into two subsets of nozzles with different fuel supply rates. The fuel control system is divided into separate control paths, allowing independent optimization of fuel delivery to each subset without requiring a completely complex centralized control system.
Solution Approach 2:
The fuel distribution system is designed to handle multiple fuel types (traditional jet A-1 and alternative fuels with higher calorific values) using the same basic infrastructure. The system can operate with different fuel blends and temperatures, providing multi-functionality without requiring separate dedicated systems for each fuel type.
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 improves combustion efficiency, reduces non-volatile particulate matter (nvPM) emissions by 20-80%, and balances combustion efficiency with coking levels, enhancing aircraft performance and reducing undesirable emissions.
Implementation Method 1
fuel-oil heat exchangers to raise the fuel temperature to 135°C and transfer heat to lower viscosity
Implementation Method 2
a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber
Implementation Method 3
a combustor, comprising a combustion chamber... providing a fuel to the plurality of fuel spray nozzles having a calorific value of at least 43.5 MJ/kg
Data Source
AI summary
A gas turbine engine has a combustor with a combustion chamber and a plurality of fuel spray nozzles including a first subset of nozzles and a second subset of nozzles. The first subset of nozzles are supplied with more fuel than the second subset of nozzles. A ratio of the number of nozzles in the first subset to the number of nozzles in the second subset is in the range of 1:2 to 1:5. A method includes providing fuel to the one or more fuel-oil heat exchangers, transferring heat from oil to the fuel, and providing the fuel from the one or more fuel-oil heat exchangers to the fuel spray nozzles. Heat is transferred from the oil to the fuel to lower a viscosity of the fuel to 0.58 mm2/s or lower on injection of the fuel into the combustion chamber at cruise conditions.