Gas Turbine Combustion Tube Outlet Section Design
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Solution Overview
Problem
The existing combustion tubes in gas turbines experience flow separation at the outlet section, leading to increased pressure loss due to a gradual increase in the flow path cross-sectional area, which is not effectively addressed by existing technologies.
Innovation Solution
The combustion tube design features an annular sector-shaped outlet section with specific inclination angles for the outer and inner walls, and side walls, which gradually decrease the cross-sectional area towards the outlet, reducing pressure loss by optimizing the flow path distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the combustion tube has a cross-sectional shape which gradually changes from circular to annular sector-shape in the outlet part, then the transition from inlet to outlet is smooth, but the flow path cross-sectional area increases halfway causing flow separation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the inclination angle θ1 of the first side wall to be 0 < θ1 ≤ 56 degrees relative to the second side wall. This angular parameter control ensures that while the cross-sectional shape transitions from circular to annular sector-shape, the flow path cross-sectional area does not increase halfway, thereby preventing flow separation while maintaining smooth geometric transition.
2Area of stationary object
If the flow path cross-sectional area increases halfway in the combustion tube, then the outlet perimeter is enlarged, but flow separation occurs leading to pressure loss
Solution Approach 1:
The patent controls the inclination angle parameter θ1 within the specific range of 0 < θ1 ≤ 56 degrees to regulate the expansion characteristics of the flow path. This parameter control allows the outlet cross-sectional area to be sufficiently large for performance while preventing intermediate area expansion that would cause flow separation and pressure loss.
Solution Approach 2:
The patent applies partial action by allowing the perimeter of the annular sector-shape to increase toward the outlet opening through the oblique arrangement of side walls, but constrains this increase to occur only in the circumferential direction rather than allowing unrestricted area expansion. This selective perimeter increase achieves the needed outlet size without the harmful intermediate expansion.
3Object-generated harmful factors
If the first side wall is arranged parallel to the second side wall, then the flow path area remains constant, but the perimeter cannot increase toward the outlet
Solution Approach 1:
The patent changes the geometric parameter by setting the inclination angle θ1 of the first side wall relative to the second side wall to be greater than 0 degrees (specifically 0 < θ1 ≤ 56 degrees). This angular parameter change enables the perimeter of the annular sector-shape to increase toward the outlet opening while controlling the flow path cross-sectional area to not increase halfway, thus avoiding flow separation.
Data Source
AI summary
A combustion tube for a gas turbine including an outlet section having a cross-section of an annular sector-shape. The outlet section includes an outer wall forming an outer peripheral boundary of the annular sector-shape, an inner wall forming an inner peripheral boundary of the annular sector-shape, and a pair of side walls forming boundaries on both sides of the annular sector-shape in a circumferential direction, respectively. The outer wall extends obliquely with respect to the inner wall such that a height of the annular sector-shape decreases toward an outlet opening of the combustion tube. A first side wall extends obliquely with respect to a second side such that a perimeter of the annular sector-shape increases toward the outlet opening of the combustion tube. An inclination angle θ1 of the first side wall with respect to the second side wall satisfies 0<θ1≤56.