Gas Turbine Exhaust Diffuser Strut Pressure Loss Reduction
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Solution Overview
Problem
In gas turbine exhaust diffusers, the variation in flow path cross-sectional area leads to significant pressure losses due to strut disposition, which reduces performance.
Innovation Solution
The introduction of a concave section on the wall surface within the flow path cross-section, which increases the cross-sectional area proportionally to offset the decrement caused by the strut, thereby attenuating pressure loss variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strut is disposed in the exhaust flow path to support the bearing, then the bearing can be held in position, but the cross-sectional area of the flow path is abruptly reduced and increased, causing pressure loss
Solution Approach 1:
The patent applies local quality by forming a concave section in the exhaust casing wall at the location where the strut is disposed. This local modification creates an expanded flow path region that compensates for the area reduction caused by the strut, thereby reducing pressure loss while maintaining bearing support functionality.
Solution Approach 2:
The patent converts the harmful effect of the strut blocking the flow path into a beneficial effect by using the strut's presence as an opportunity to create a concave section. This concave section serves as a flow path expansion region that actively reduces pressure loss, transforming the obstacle into a flow optimization feature.
2Ease of manufacture
If the flow path cross-sectional area is varied to accommodate the strut, then the strut can be installed, but pressure loss occurs due to abrupt area changes
Solution Approach 1:
The patent uses curvature by forming a concave section with a smooth curved surface in the exhaust casing wall. This curved expansion region allows fluid to flow around the strut smoothly, avoiding abrupt area changes and reducing pressure loss while maintaining ease of strut installation.
3Loss of energy
If the cross-sectional area is increased by the concave section to offset the strut, then pressure loss is suppressed, but the structure becomes more complex
Solution Approach 1:
The patent merges the strut support function with the flow path structure by integrating the concave section directly into the exhaust casing wall where the strut is disposed. This combination achieves pressure loss reduction without adding separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The exhaust casing wall serves dual functions: it provides structural support and simultaneously creates the concave section for flow path expansion. The wall structure itself performs the pressure loss reduction function, eliminating the need for additional dedicated components.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is a flow path structure equipped with wall surfaces (lOb, 11b) that form a flow path, structures (12, 13) provided extending from the aforementioned wall surfaces in a direction intersecting the primary flow direction of the fluid flowing in the flow path, and recess formation regions (20, 30) in which recesses (21, 22, 31, 32) are formed in the aforementioned wall surfaces across a range in the primary flow direction that includes the aforementioned structures. The aforementioned structures occupy a portion of the flow path in the cross section of the flow path that intersects the aforementioned primary flow, and thus the cross-sectional area of the flow path changes as the flow path proceeds in the primary flow direction.