Gas Turbine Transition Piece Inclined Surface Vortex Suppression
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Solution Overview
Problem
Conventional gas turbines experience issues with Karman vortex street formation between combustors, leading to pressure fluctuations, NOx emissions increases, and decreased efficiency due to deviations in combustion gas flow rates across combustors.
Innovation Solution
The design incorporates inclined surfaces on the inner surfaces of transition pieces to increase passage area, optimizing the positional relationship between transition pieces and first stage vanes, with specific ratios of S/P and L/P to prevent Karman vortex street formation and flow rate deviations, and includes configurations such as aligned upstream ends of vanes and varying throat widths for enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inclined surfaces are provided on the downstream side of the transition piece to prevent Karman vortex street formation, then pressure fluctuations are suppressed, but flow rate deviation between combustors increases leading to temperature non-uniformity
Solution Approach 1:
The patent applies local quality by providing inclined surfaces only at specific locations (downstream side of transition piece at heights of 0.05D to 0.40D from the axis) rather than uniformly across the entire structure. This localized application prevents Karman vortex street formation at critical positions while maintaining proper flow distribution to combustors, thus resolving the contradiction between pressure fluctuation suppression and flow rate uniformity
2Ease of operation
If the transition piece geometry is modified to increase passage area, then flow rate distribution improves, but Karman vortex street formation is promoted
Solution Approach 1:
The patent employs asymmetry by configuring inclined surfaces that slope toward the centerline of the gas turbine, creating asymmetric flow patterns that promote uniform distribution to combustors. Simultaneously, this asymmetric configuration disrupts the symmetry required for Karman vortex street formation, thereby achieving both improved flow distribution and vortex suppression
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 effectively suppresses Karman vortex streets, reduces NOx emissions, and maintains turbine efficiency by ensuring uniform combustion gas flow across combustors.
Implementation Method 1
Immediately after the combustion gas flows out of the transition piece, a Karman vortex street may formed in the flow between side flanges of neighboring transition pieces
Data Source
AI summary
A gas turbine combustor and a gas turbine; wherein inclined surfaces are provided on inner surfaces of side walls neighboring in a circumferential direction at downstream end portions of transition pieces of combustors, the inclined surfaces being configured to increase a passage area of the transition pieces, a ratio (S/P) is from 0 to 0.2, where (P) is a pitch dimension of first stage vanes, and (S) is a circumferential dimension from an intermediate point between neighboring transition pieces to an upstream end of a first stage vane closest in the circumferential direction; and a ratio (L/P) is from 0.3 to 0.55, where (P) is the pitch dimension, and (L) is an axial dimension from a downstream end of the transition piece to the upstream end of the first stage vane.