First-Stage Stationary Blade Segment Layout for Seal Ring Clearance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The design of stationary blade segments, casings, and rotors in steam turbines is constrained, limiting the degree of freedom in achieving high turbine efficiency.
Innovation Solution
The design of the first-stage stationary blade segment includes an outer ring with a specific configuration that shifts the embedded portion upstream, reducing protrusions downstream and allowing for a seal ring to be mounted without widening the gap between the stationary and rotor blades, thereby increasing design freedom while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the embedded portion of the outer shroud is positioned conventionally (aligned with blade edges), then the blade structure is simple, but the casing design freedom is limited and seal ring mounting requires widening the axial gap which reduces turbine efficiency
Solution Approach 1:
The embedded portion of the outer shroud is shifted in the axial direction (another dimension) relative to the blade body, creating a stepped configuration. This dimensional offset allows the seal ring to be mounted on the casing without requiring an increased axial gap between the stationary and rotor blades, thus maintaining turbine efficiency while providing design freedom for the casing structure
Solution Approach 2:
The outer shroud is divided into a shroud main body and a separate embedded portion that can be positioned independently. This segmentation allows the embedded portion to be located upstream of the blade body edges, creating space for seal ring mounting on the casing without affecting the blade's aerodynamic performance or requiring gap widening
2Ease of manufacture
If the axial gap between stationary and rotor blades is widened to accommodate seal ring mounting, then the seal ring can be installed, but turbine efficiency is reduced
Solution Approach 1:
Instead of increasing the axial gap dimension, the solution utilizes the radial dimension by positioning the embedded portion of the outer shroud upstream of the blade edges. This creates axial space on the casing for seal ring mounting without increasing the operational axial gap between stationary and rotor blades, thereby avoiding efficiency loss
3Adaptability or versatility
If the embedded portion is shifted upstream, then seal ring mounting is enabled without gap widening, but the blade structure becomes more complex
Solution Approach 1:
The outer shroud is segmented into a shroud main body and an embedded portion that can be independently positioned and manufactured. This segmentation allows the embedded portion to be shifted upstream to enable seal ring mounting while keeping the blade body structure relatively simple, as the embedded portion can be attached or integrated with minimal structural modification
Solution Approach 2:
The embedded portion acts as an intermediary element between the outer shroud and the casing, providing a mounting surface for the seal ring on the casing without requiring modifications to the main blade body structure. This intermediary component isolates the complexity to a small, localized feature rather than the entire blade structure
Data Source
AI summary
A first-stage stationary blade segment includes an outer ring extending in a circumferential direction, and a plurality of first-stage stationary blades attached on a radially inner side of the outer ring so as to be aligned in the circumferential direction. Each of the first-stage stationary blades has a blade body extending in the radial direction, and an outer shroud formed on a radially outer side of the blade body with respect to an axis. The outer shroud has a shroud main body, and an embedded portion connected to the radially outer side of the shroud main body. The embedded part has an embedded front end surface facing the side upstream along the axis, and an embedded rear end surface facing the side downstream along the axis. The outer ring has outer ring grooves into which the outer shrouds of each of the plurality of first-stage stationary blades is inserted.