Swirl Vane Curved Root Cutout for Flashback Suppression
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Solution Overview
Problem
Existing combustion burners with swirlers face issues of flashback due to unstable axial-flow velocity and insufficient mixing, leading to potential damage and inefficient combustion.
Innovation Solution
A combustion burner design with swirl vanes that communicate radially-outer and radially-inner flow paths, featuring a curved cutout on the root portion to enhance axial-flow velocity and mixing, utilizing the Coanda effect to stabilize flow and promote uniform fuel distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a cutout is provided on the rear edge at the radially inner side of a swirl vane to increase axial-flow velocity, then flashback is suppressed, but flow separation occurs at the downstream side of the cutout generating turbulence which causes great fluctuation of axial-flow velocity
Solution Approach 1:
The invention applies curvature by forming a curved surface at the downstream region of the pressure surface of the root portion, which curves in a direction opposite to the swirl direction toward the trailing edge. This curved surface design guides the flow smoothly along the surface, preventing flow separation and turbulence that would occur with sharp edges, thereby maintaining stable axial-flow velocity while still achieving flashback suppression.
Solution Approach 2:
The invention implements local quality by creating different surface characteristics at different locations of the swirl vane. The tip portion has a curved surface curving in the swirl direction to generate swirl flow, while the root portion has a curved surface curving in the opposite direction to control axial flow. These localized surface variations allow the vane to perform multiple flow control functions simultaneously, achieving both flashback resistance and flow stability.
2Speed
If a partition wall is used to separate air channel regions to increase axial-flow velocity at the inner side, then flashback is prevented, but mixing between air and fuel becomes insufficient
Solution Approach 1:
The invention merges the radially-outer and radially-inner flow path regions by providing communication between them without partition walls. This allows both air and fuel to mix thoroughly in the axial flow path while the swirl vane's curved surfaces maintain adequate axial-flow velocity. The merging of flow regions eliminates the mixing deficiency caused by partition walls while preserving flashback resistance through the vane's geometric design.
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
The design effectively increases mean axial-flow velocity and improves flashback resistance while maintaining good mixing performance, leading to a more stable and efficient combustion process.
Implementation Method 1
the gas is attracted toward the curved surface by the Coanda effect to be rectified in a direction opposite to the swirl direction
Implementation Method 2
a tip portion for swirling gas in a swirl direction, the gas flowing through a radially-outer region of the axial flow path
Implementation Method 3
a combustion burner for supplying a combustion space with fuel and an oxidant such as air to form flames
Data Source
AI summary
A combustion burner includes a nozzle and a swirl vane disposed in an axial flow path extending along an axial direction of the nozzle. The swirl vane includes a tip portion for swirling gas, the gas flowing through a radially-outer region of the axial flow path, and a root portion disposed on an inner side in a radial direction of the nozzle, the root portion having a cutout on a side of a trailing edge. The radially-outer region and a radially-inner region of the axial flow path communicate with each other, at least in a range in the axial direction in which the swirl vane is disposed. The swirl vane has a pressure surface, a downstream region of the pressure surface of the root portion being defined by the cutout as a curved surface which curves in a direction opposite to the swirl direction toward the trailing edge.