Lean Burn Combustor S-Shaped Recirculation Zone
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Solution Overview
Problem
Gas turbine engines face challenges in reducing NOx, CO, and UHC emissions while maintaining efficient combustion, as lean burn combustion technologies often result in incomplete combustion and flame instability, affecting engine operability and emissions across aircraft, industrial, and marine applications.
Innovation Solution
A lean burn combustor design featuring a unique S-shaped recirculation zone within the primary combustion zone, optimized by specific non-dimensional parameter ratios, which supports the combustion of pilot and main fuel mixtures, enhancing combustion efficiency and minimizing NOx and smoke emissions, and allowing for scalable design across various engine sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lean burn combustion is used to reduce NOx emissions, then combustion temperature is reduced, but combustion completeness deteriorates leading to increased CO and UHC emissions
Solution Approach 1:
The combustor chamber is divided into a primary combustion zone and a secondary combustion zone, each with different geometric characteristics. The primary zone has a specific length-to-diameter ratio (1.5 < L/d < 5) to establish recirculation, while the secondary zone provides additional combustion space, allowing staged combustion that reduces NOx while ensuring complete burnout of CO and UHC
Solution Approach 2:
The invention optimizes the geometric parameters of the combustor chamber, specifically the length-to-diameter ratio (L/d) of the primary combustion zone and the volume ratio between primary and secondary zones. By controlling these parameters within specific ranges, the recirculation flow pattern is optimized to maintain low combustion temperature (reducing NOx) while ensuring sufficient residence time and mixing (reducing CO and UHC)
2Object-affected harmful factors
If lean burn combustion is used to reduce NOx emissions, then combustion temperature is reduced, but flame stability deteriorates causing rumble and fatigue failure
Solution Approach 1:
The primary combustion zone is designed with specific geometric properties (length-to-diameter ratio between 1.5 and 5) that create a recirculation flow pattern localized to that zone. This recirculation concentrates heat and maintains stable flame anchoring in the primary zone, while the overall lean burn condition (low combustion temperature) is maintained throughout the combustor to reduce NOx emissions
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 lean burn combustor effectively reduces NOx, CO, and UHC emissions while improving engine operability by optimizing combustion efficiency through the S-shaped recirculation zone, maintaining efficient combustion across different engine sizes and applications.
Implementation Method 1
the burning mixture of pilot fuel and air coming from the pilot fuel injector may form an S-shaped flow recirculation
Data Source
Figure 1~2
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Figure 5~6
AI summary
A lean burn combustor (16) comprises a plurality of lean burn fuel injectors (50), each comprising a fuel feed arm (52) and a lean burn fuel injector head (54) with a lean burn fuel injector head tip (72), wherein the lean burn fuel injector head tip has a lean burn fuel injector head tip diameter (d), the lean burn fuel injector head comprising a pilot fuel injector and a main fuel injector, the main fuel injector being arranged coaxially and radially outwards of the pilot fuel injector; and a combustor chamber (60) extending along an axial direction (62) for a length (L) and comprising a radially inner annular wall (64), a radially outer annular wall (66), and a meter panel (68) defining the size and shape of the combustor chamber, wherein the combustor chamber comprises a primary combustion zone (80) and a secondary combustion zone (82). A ratio L/d of the combustor chamber length to the lean burn fuel injector head tip diameter is less than 5.