Stator Blade Segment Set Screw Drain Hole Design
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Solution Overview
Problem
Existing steam turbines face performance deterioration due to moisture loss and rotor blade erosion from drain condensate, with challenges in forming small drain discharge holes to efficiently discharge condensate while minimizing steam outflow.
Innovation Solution
A stator blade segment design featuring a set screw with a male thread on the outer periphery and a female thread on the inner periphery, allowing for a smaller diameter drain hole, along with a drain recessed portion and chamber to efficiently collect and discharge condensate, reducing steam outflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drain discharge hole diameter is reduced to suppress steam outflow, then steam loss is reduced, but the difficulty of forming the hole increases
Solution Approach 1:
A set screw is introduced as an intermediary component to form the drain discharge hole. The set screw includes a body with a through-hole that can be easily formed, and this hole serves as the drain discharge hole. This intermediary approach allows for small diameter holes to be formed without direct drilling of the blade root ring, thus reducing steam loss while maintaining manufacturing ease.
Solution Approach 2:
The drain discharge hole is segmented into two parts: a first drain discharge hole formed in the set screw body, and a second drain discharge hole formed in the blade root ring. This segmentation allows each hole to be optimized independently, with the set screw hole being easier to form at small diameter, while the blade root ring hole can be formed separately.
2Loss of energy
If a set screw is used to form the drain discharge hole, then the hole diameter can be reduced, but the device complexity increases
Solution Approach 1:
The set screw serves multiple functions: it acts as a fastening component to secure the stator blade to the blade root ring, and simultaneously provides the drain discharge hole through its body. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving small hole diameter.
Solution Approach 2:
The set screw integrates the fastening function and the drain discharge function into a single component. The body of the set screw contains the through-hole that serves as the drain discharge hole, merging what would traditionally be separate components into one unified element.
3Device complexity
If the drain discharge hole is formed directly in the blade root ring, then the structure is simpler, but the ability to form small diameter holes is limited
Solution Approach 1:
The set screw acts as an intermediary that enables precise small diameter hole formation. Instead of directly drilling small holes in the blade root ring, the set screw's through-hole provides a precise, easily formable small diameter opening that achieves the required manufacturing precision.
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 enables efficient discharge of condensate while suppressing steam outflow, maintaining a stable driving state of the steam turbine.
Implementation Method 1
a set screw which has a screw main body, a male thread portion which is formed on an outer periphery of the screw main body, and a drain hole which penetrates a central portion of the screw main body in an extension direction of the screw main body
Data Source
AI summary
A set screw (56) is provided, which has a screw main body (71), a male thread portion (75) which is formed on an outer periphery of the screw main body (71), and a drain hole (78) which penetrates a central portion of the screw main body (71) in an extension direction of the screw main body (71). The blade root ring (53) has a hole (63) which extends radially outward from an inner peripheral surface (53a) of the blade root ring (53), and a female thread portion (64) which is formed on an inner peripheral surface (63a) of the hole (63), and the set screw (56) is screwed into the female thread portion (64).