Aerodynamically Enhanced Premixer for Gas Turbine Emissions
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Solution Overview
Problem
Existing gas turbine engine premixers face challenges in increasing flow velocity at the boundary layer while optimizing vane shape and swirler positioning to reduce emissions of NOx, unburned hydrocarbons, and carbon monoxide, particularly in urban areas, while maintaining fuel efficiency and operational costs.
Innovation Solution
The implementation of an aerodynamically enhanced premixer design that controls the boundary layer profile through reduced mixer-to-mixer proximity, premixer vane tilt with compound angles, reduced nozzle/mixer tilt sensitivity, mixer foot contouring, and the use of purge slots, along with a twin radial mixer, to optimize fuel efficiency and emission reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mixer-to-mixer proximity is reduced and swirlers are positioned closer together, then fuel efficiency is improved and emissions are reduced, but boundary layer control becomes more difficult to optimize
Solution Approach 1:
The patent applies local quality by tilting only specific premixer vanes by specific angles (e.g., 10-30 degrees) to create localized flow control zones. This selective vane tilting optimizes the boundary layer profile at critical locations near the fuel nozzle while maintaining simpler structures elsewhere, resolving the contradiction between improved fuel efficiency and reduced control complexity.
Solution Approach 2:
The patent implements preliminary action by pre-configuring the vane tilt angles and mixer spacing during the design phase to establish optimal boundary layer profiles before combustion occurs. This preliminary geometric configuration eliminates the need for complex active control systems during operation, thereby improving fuel efficiency while keeping the control system simple.
2Object-generated harmful factors
If premixer vane tilt with compound angles is used, then boundary layer profile control is improved and emissions are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the vane structure into multiple sections with different tilt angles (compound angles), where each segment is optimized for a specific function. This segmentation allows for reduced emissions through improved boundary layer control while enabling modular manufacturing that可以降低 precision requirements for each individual segment compared to a fully complex single-piece design.
3Reliability
If nozzle/mixer tilt sensitivity is reduced, then system robustness is improved, but flow velocity control at the boundary layer becomes more challenging
Solution Approach 1:
The patent implements self-service through the reduced nozzle/mixer tilt sensitivity design, where the geometry is configured to automatically maintain stable flow characteristics without requiring precise alignment during installation. The self-aligning feature robustly maintains flow velocity at the boundary layer through inherent geometric properties rather than active control, resolving the contradiction between system robustness and flow velocity control.
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 design achieves improved fuel efficiency and reduced emissions by enhancing boundary layer control, minimizing aerodynamic losses, and allowing for closer swirler positioning, resulting in a 10-20% reduction in NOx emissions and increased fuel atomization efficiency.
Implementation Method 1
a boundary layer profile over the fuel nozzle (center-body) is controlled to minimize emissions
Implementation Method 2
aerodynamically enhanced premixer design that controls the boundary layer profile
Implementation Method 3
premixer vane tilt to include the use of compound angles... increased flow velocity at the flow boundary layer... mixing efficiency
Implementation Method 4
Additional boundary layer control is realized using purge slots... and a splitter when employed with a twin radial mixer... increased fuel atomization efficiency
Data Source
AI summary
A System for Aerodynamic Premixer for Reduced Emissions comprising a premixer is generally cylindrical in form and defined by the relationship in physical space between a first ring, a second ring, and a plurality of radial vanes. The first and second rings are found to be generally equidistant, one from the other, at all points along their facing surfaces. Radial vanes connect the first ring to the second ring and thereby form the premixer.