Active Swirl Control for Flame Stabilization in Gas Turbine Burners
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Solution Overview
Problem
Thermal acoustic oscillations in gas turbine combustion chambers lead to mechanical damage, reduced efficiency, and increased emissions, particularly in lean operation modes, where burner flames are sensitive to flow perturbations and acoustics, limiting the effectiveness of existing damping systems.
Innovation Solution
Active control of swirl number perturbations in the vortex flow of air/fuel mixtures before ignition, altering the phase and amplitude of tangential velocity fluctuations to minimize flame transfer function amplitudes, thereby reducing thermo-acoustic oscillations and enhancing flame stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If passive damping systems like Helmholtz dampers are implemented, then thermal acoustic oscillations are reduced, but large damping volumes are required which increase costs and space requirements
Solution Approach 1:
The patent replaces passive mechanical damping systems (Helmholtz dampers) with active control mechanisms that use sensors and actuators to dynamically counteract thermal acoustic oscillations. This substitution eliminates the need for large damping volumes while maintaining effective oscillation reduction through real-time flow rate modulation.
Solution Approach 2:
The invention changes the operating parameters of the burner system by dynamically modulating the fuel mass flow rate in response to detected oscillations. By adjusting flow rates actively rather than using fixed-volume passive dampers, the system achieves oscillation control without requiring large physical damping volumes.
2Object-affected harmful factors
If Helmholtz dampers are used for damping, then thermal acoustic oscillations are reduced, but the absorption bandwidth is narrow making the system sensitive to detuning
Solution Approach 1:
The patent implements a dynamic control system that actively adjusts damping parameters in real-time based on operating conditions. Unlike fixed-frequency Helmholtz dampers, the active system uses feedback control to adapt to varying oscillation frequencies across different operating ranges, providing broad bandwidth effectiveness without sensitivity to detuning.
Solution Approach 2:
The invention employs feedback control where sensors detect thermal acoustic oscillations and the control system responds by modulating fuel flow rates. This closed-loop approach allows the system to adapt to changing oscillation characteristics across different operating conditions, achieving broad bandwidth damping that is not sensitive to frequency detuning.
3Object-generated harmful factors
If burner systems operate in lean mode for emission compliance, then pollution emissions are reduced, but the burner flame becomes extremely sensitive to flow perturbations causing thermo-acoustic instabilities
Solution Approach 1:
The patent uses feedback control to detect flow perturbations and thermo-acoustic oscillations in lean-burn mode operation. The control system responds by actively modulating fuel flow rates to counteract instabilities, allowing the system to maintain both low emissions and flame stability that would otherwise be incompatible in lean operation.
Solution Approach 2:
The invention applies preliminary anti-action by detecting incipient oscillations and flow perturbations before they develop into full thermo-acoustic instabilities. The control system takes preemptive action by adjusting fuel flow rates to counteract developing instabilities, maintaining flame stability in lean mode without compromising emission performance.
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
Significantly reduces flame oscillation amplitudes, optimizing burner efficiency and emissions by actively managing swirl number perturbations using computational fluid dynamics and various control mechanisms, such as magnetic levitation, fluid injection, and dielectric barrier discharge, across different swirler types.
Implementation Method 1
a vortex flow of an ignitable air fuel mixture is generated before entering the combustor in which the vortex flow breaks down and forming a central revers flow zone (CRZ) which allows anchoring of the premix flame
Implementation Method 2
When the heat release from the flame is coupled with the acoustics of the combustion chamber very high perturbation amplitudes can occur
Implementation Method 3
the burner flame during this mode of operation is extremely sensitive to flow perturbations and can easily couple with the acoustics of the combustion chamber
Data Source
AI summary
The invention refers to a method and a device for flame stabilization in a burner system of a stationary combustion engine, preferably a stationary gas turbine, in which a flow of an air/fuel mixture is produced and being swirled to form a vortex flow to which a swirl number is assignable before entering a combustion zone in which the vortex flow of the air/fuel mixture is ignited to form a flame within a reverse flow zone caused by vortex breakdown. The swirl number perturbation driven by thermoacoustic oscillation inside the burner system is controlled by affecting the vortex flow actively before entering the combustion zone on basis of changing a flame transfer function assigned to the burner system with the proviso of minimizing pulsation amplitudes of the flame transfer function.