Dual Wall Combustor Inserts for NOx Reduction
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Solution Overview
Problem
Modern gas turbine combustors face challenges in reducing NOx emissions and maintaining operability at high temperatures, particularly in the quench zone where fuel-rich gases are rapidly mixed with excess air, requiring effective cooling schemes that address aerodynamic and mechanical design complexities.
Innovation Solution
A dual wall combustor design with impingement-effusion cooling and inserts mounted on the hot walls to guide pressurized air from the cold walls into the combustion chamber, providing a metering function and strain isolation between the hot and cold walls, which helps in minimizing NOx emissions and optimizing temperature profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperatures are used to achieve high operability and low NOx emissions, then combustor performance is improved, but cooling requirements increase and design complexity worsens
Solution Approach 1:
The combustor is divided into multiple zones (rich burn zone, quench zone, lean burn zone) with distinct cooling requirements. The dual wall liner structure segments the cooling system into inner and outer walls, each with independent cooling hole patterns. This segmentation allows optimized cooling for each zone without increasing overall system complexity.
Solution Approach 2:
Different cooling strategies are applied to different regions: the inner wall uses impingement cooling with holes facing the combustion chamber, while the outer wall uses effusion cooling with holes facing the annular passage. The quench zone receives enhanced cooling attention with specific hole distributions. This local quality approach optimizes cooling efficiency without requiring complex global cooling systems.
2Object-generated harmful factors
If effective cooling is implemented in the quench zone to minimize NOx emissions, then emission performance is improved, but aerodynamic and mechanical design challenges increase
Solution Approach 1:
The quench zone is provided with enhanced local cooling through specific hole distributions in both inner and outer walls. The inner wall holes are positioned to cool the quench zone where fuel-rich gases mix with excess air. This localized approach minimizes NOx emissions without requiring complex global geometric modifications.
Solution Approach 2:
The quench zone cooling is achieved by segmenting the cooling function between inner wall impingement holes and outer wall effusion holes. This segmentation allows independent optimization of each cooling mechanism without increasing overall geometric complexity.
3Temperature
If dual wall liners with impingement-effusion cooling are used to cool the combustor, then temperature control is improved, but structural complexity increases
Solution Approach 1:
The inner and outer wall cooling systems are merged into a unified dual wall liner structure. The impingement cooling from inner wall holes and effusion cooling from outer wall holes work together as an integrated system. This merging provides effective temperature control while reducing the number of separate cooling systems needed.
Solution Approach 2:
The dual wall liner structure serves multiple functions simultaneously: structural containment, heat shielding, and dual-mode cooling (impingement and effusion). The annular passage between walls serves both as a structural element and as a cooling fluid pathway. This multi-functionality reduces overall system complexity.
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 dual wall combustor design effectively reduces NOx emissions and enhances operability by precisely controlling air and fuel stoichiometries, ensuring efficient cooling and aerodynamic performance in the quench zone, thereby improving the overall efficiency and durability of gas turbine engines.
Implementation Method 1
a first wall including a plurality of impingement cooling holes
Implementation Method 2
a dual wall structure with the first wall, the second wall proximate to the first wall
Implementation Method 3
a second wall including a plurality of effusion cooling holes
Implementation Method 4
an insert mounted in the second primary orifice configured to receive an air jet from the first primary orifice and to guide the air jet through the second wall
Data Source
Figure 1
Figure 2
AI summary
A combustor includes a first liner; and a second liner forming a combustion chamber with the first liner. The combustion chamber is configured to receive an air-fuel mixture for combustion therein, and the first liner is a first dual wall liner having a first hot wall facing the combustion chamber and a first cold wall. The first cold wall has a first cold wall orifice and the first hot wall has a first hot wall orifice. A first insert is mounted in the first hot wall orifice and is configured to receive a first air jet of pressured air from the first cold wall orifice, and guide the first jet through the first hot wall orifice and into the combustion chamber.