Angled Neck Damper for Gas Turbine Grazing Flow
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Solution Overview
Problem
Conventional gas turbine dampers experience reduced performance due to high velocity grazing flows, which restrict the passage of bias flow and negatively impact acoustic damping, limiting their placement to regions with lower grazing flow velocities.
Innovation Solution
The damper design includes a neck with a mouth whose longitudinal axis is angled between 0°-90° relative to the air flow direction, allowing the neck to protrude and bend along the flow direction, or form a slanted channel, and optionally feature a shield to deflect flow, thereby modifying fluid dynamics and reducing the detrimental effect of grazing flows on damping performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the damper is placed in regions with high grazing flow velocity, then the damping performance deteriorates, but the damper can be placed in more locations including preferred locations
Solution Approach 1:
The neck is configured with a specific geometric orientation (longitudinal axis at 0°-90° to grazing flow direction) that creates localized flow conditions at the mouth. This local geometric modification changes the flow distribution specifically at the damper location, reducing the detrimental effect of grazing flow while maintaining the overall chamber flow patterns.
Solution Approach 2:
The invention changes the geometric parameters of the neck (orientation angle, bending shape, slant angle) to modify the fluid dynamic parameters (flow distribution, velocity profile) at the mouth. This parameter change allows the damper to operate effectively in regions with high grazing flow velocity by altering how the flow interacts with the neck structure.
2Reliability
If the neck is configured to protrude and bend or form slanted channel, then the detrimental effect of grazing flow is reduced, but the device complexity increases
Solution Approach 1:
The neck is configured to bend along the flow direction, creating a curved or slanted channel geometry instead of a straight cylindrical shape. This curvature modifies the flow path and distribution at the mouth, reducing the detrimental effect of grazing flow on damping performance while maintaining structural integrity.
3Productivity
If the neck longitudinal axis is angled 0°-90° relative to air flow direction, then the flow distribution at mouth is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention specifies a range of acceptable orientation angles (0°-90°) for the neck longitudinal axis relative to the air flow direction. This parameter specification provides manufacturing flexibility while ensuring the flow distribution at the mouth is sufficiently modified to reduce grazing flow effects and maintain damping efficiency.
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 configuration enhances damping performance by minimizing the interference of strong grazing flows, allowing effective placement in regions with high grazing flow velocities and maintaining acoustic damping efficiency.
Implementation Method 1
The resonator cavity 11 acts as a spring for air expansion and contraction in the cavity
Implementation Method 2
The air in the neck 12 behaves as a mass connected to the spring. This system has one or more resonance frequencies. When acoustic waves are at a frequency close to one of the resonance frequencies of the damper and impinge the mouth of the neck, the damper reduces or damps such pulsations. The mass of air oscillates due to the spring effect of the cavity.
Implementation Method 3
The oscillation of the air through the neck triggers vortex shedding at the neck. In this way, acoustic energy is converted into aerodynamic energy which ultimately dissipates into heat.
Data Source
AI summary
The invention relates to a damper for reducing the pulsations in a chamber of a gas turbine. The damper includes a resonator cavity and a neck in flow communication with the resonator cavity and the chamber. The neck includes a mouth to communicate with the chamber. The air flow inside the chamber flows across the mouth of the neck. The neck is so configured that the longitudinal axis of its mouth is angled 0-90° relative to the direction of the air flow inside the chamber. The damper of this invention may effectively alleviate the detrimental effect of the grazing flow and thus it enables the placement of the damper also at locations where strong grazing flows are present.