Beveled Grommet Quench Flow Control in Gas Turbine Combustors
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Solution Overview
Problem
Annular combustors in gas turbine engines face challenges in controlling quench flow variability, which affects combustion stoichiometry and generates undesirable emissions due to the pressure differential and abrupt corners in traditional grommet designs.
Innovation Solution
The introduction of a grommet with a bevel surface angled between 35°-55°, specifically 45°, and a circumferential flange, integrated as a unitary structure with heat shield panels, to control air flow through the quench ports, reducing flow variability by geometrically defining axial and radial lengths that influence the coefficient of discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional grommet design with abrupt corners is used, then manufacturing is simpler, but quench flow variability increases causing combustion instability and emissions
Solution Approach 1:
The grommet incorporates a beveled edge at the quench port inlet with specific angle (30-45 degrees) and dimensions (axial length 0.5-2mm, radial length 0.5-2mm), creating localized geometric modification only where flow control is needed. This local quality change stabilizes quench flow without requiring complex overall grommet redesign, resolving the contradiction between combustion stability and device complexity.
2Temperature
If quench flow rate increases to control combustion temperature, then combustion stoichiometry improves, but flow variability increases generating undesirable emissions
Solution Approach 1:
The beveled edge geometry parameters (angle of 30-45 degrees, axial length 0.5-2mm, radial length 0.5-2mm) are optimized to control the coefficient of discharge and stabilize quench flow. This parameter optimization ensures consistent mass flow rate across varying pressure differentials, maintaining proper combustion stoichiometry and temperature control while minimizing emissions from flow variability.
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 enhances control over quench flow, stabilizes temperature distribution in the combustion chamber, and reduces emissions by minimizing flow variability through the grommet, thereby improving combustor performance.
Implementation Method 1
The introduction of a grommet with a bevel surface angled between 35°-55°, specifically 45°, and a circumferential flange, integrated as a unitary structure with heat shield panels, to control air flow through the quench ports, reducing flow variability by geometrically defining axial and radial lengths that influence the coefficient of discharge.
Data Source
Figure 1~2B
Figure 3~5
Figure 6
AI summary
A combustor includes a shell comprising a peripheral wall and a heat shield panel, the shell at least partially defines a combustion chamber. A grommet is integrated as a unitary structure in the shield panel or the peripheral wall. The grommet has a body that defines a passage through the grommet that is operable to communicate air from outside the combustion chamber into the combustion chamber. The body carries a first surface, an opposite, second surface and a third surface that defines the passage and joins the first surface and the second surface. The third surface includes a bevel surface with respect to at least one of the first surface and the second surface.