Acoustic Damper Sealing Gas Deflects Grazing Flow
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Solution Overview
Problem
Existing acoustic damping devices in gas turbines fail to effectively damp combustion dynamics at specific frequencies due to interference from grazing gas flows, which disrupt the bias flow through the damper, reducing their performance.
Innovation Solution
The introduction of strategically located openings for sealing gas, which deflects the grazing flow away from the damper's mouth, protecting the bias flow and enhancing the damper's performance by using a high-pressure gas to create an aerodynamic shield, optimizing the cross-section of these openings for efficient deflection and minimal gas consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acoustic damping devices are installed in chambers with grazing flow, then combustion dynamics can be reduced at resonance frequencies, but the grazing flow disturbs the bias flow through the neck and mouth, reducing damping effectiveness
Solution Approach 1:
A sealing gas flow is introduced as an intermediary substance between the grazing flow and the damper mouth. This sealing gas creates a protective barrier that deflects the harmful grazing flow away from the damper opening, allowing the bias flow to maintain its intended path and function without interference. The sealing gas acts as a mediator that shields the sensitive damper region from the disruptive external flow while permitting the damper to operate effectively.
2Reliability
If sealing gas is introduced to protect the damper from grazing flow, then damping performance is improved, but additional gas consumption and system complexity increase
Solution Approach 1:
Rather than attempting to completely block or stop the grazing flow, the invention applies partial action by introducing a sealing gas flow that provides just enough protection to deflect the harmful components of the grazing flow away from the damper mouth. The sealing gas flow rate is optimized to be sufficient for protection but not excessive, balancing performance improvement with gas consumption considerations.
Solution Approach 2:
The sealing gas system is designed to utilize readily available high-pressure gas sources already present in the gas turbine system, such as compressor outlet gas or combustion chamber gas. This self-service approach allows the system to generate its own protective sealing flow without requiring external gas supplies or additional complex infrastructure, thereby minimizing overall system complexity while achieving the desired protection.
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 solution improves the effectiveness of acoustic dampers by preventing grazing flow interference, ensuring consistent and efficient damping across a broader frequency range, thereby reducing combustion dynamics and enhancing the overall efficiency of gas turbines.
Implementation Method 1
The sealing gas, air or any other suitable gas, that flows through the at least one opening into the chamber has the effect of a 'fence' or a shield that protects the mouth of the damper from grazing flow
Implementation Method 2
Combustion dynamics in the meaning of this application comprises pulsations, acoustic oscillations, pressure and velocity fluctuations
Implementation Method 3
Excessive pressure fluctuations may result in damage of machine components
Data Source
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AI summary
An acoustic damping device is suggested comprising at least one opening (27) for a sealing gas (29) to deflect a grazing gas flow (19, 19.2) away from the mouth (17) of an acoustic damper (11).