Turbine Tip Balance Slits for Leakage Jet Mixing Loss Control
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Solution Overview
Problem
Steam leakage between components of a steam turbine leads to reduced efficiency, mixing losses, and increased thermal stresses, affecting the turbine's performance and lifespan due to high temperatures.
Innovation Solution
A leakage flow control system that includes a tip shroud, diaphragm, extension ring, and tip balance slit to direct and manage tip leakage jets, reintroducing them into the mainstream flow to minimize losses and enhance steam blanketing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If tip leakage flow is allowed to occur naturally between the tip shroud and extension ring, then the turbine structure remains simple, but steam leakage reduces efficiency and causes mixing losses
Solution Approach 1:
The tip leakage flow is segmented into multiple controlled paths using the tip balance slit. The slit divides the leakage flow into discrete jets that can be independently directed, allowing precise control over where the leakage steam is reintroduced into the mainstream flow, thereby reducing mixing losses while maintaining a relatively simple structural addition.
Solution Approach 2:
The tip balance slit acts as an intermediary structure between the tip leakage source and the mainstream flow. It mediates the interaction by controlling the direction and location where leakage steam is reintroduced, transforming the harmful uncontrolled mixing into a controlled process that minimizes energy loss.
2Loss of energy
If tip leakage jet is directed around the diaphragm and through extension rings, then mixing losses are reduced, but the system requires additional components increasing complexity
Solution Approach 1:
The extension ring serves multiple functions: it provides structural support, defines the tip clearance gap, and works in conjunction with the tip balance slit to control leakage flow direction. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The tip balance slit is positioned and configured in advance to pre-direct the leakage jet along a specific path around the diaphragm. This preliminary action ensures that the leakage steam is already on the correct trajectory before it encounters the mainstream flow, reducing the need for additional corrective components downstream.
3Productivity
If tip leakage jet is reintroduced into mainstream flow downstream, then stage efficiency increases by 0.50%, but requires precise positioning of the tip balance slit
Solution Approach 1:
The tip balance slit is designed with specific local characteristics including its position in the extension ring, its dimensions, and its orientation. These local qualities are optimized to achieve the desired flow control effect at the specific location where leakage steam is reintroduced, maximizing efficiency gain while keeping manufacturing requirements practical.
Solution Approach 2:
The design allows for adjustment of key parameters such as the tip balance slit position, size, and angle to optimize performance. By providing design flexibility in these parameters, the system can achieve the target 0.50% efficiency improvement while accommodating reasonable manufacturing tolerances and positioning variations.
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 system achieves a 0.50% stage efficiency gain, reduces mixing and secondary losses, and improves mechanical reliability without increasing complexity or cost, while maintaining or enhancing turbine output.
Implementation Method 1
Steam may generally flow through a number of turbine stages typically disposed in series through first-stage guides and blades
Implementation Method 2
directing a tip leakage jet between a tip shroud and a first extension ring of a turbine, directing the tip leakage jet around a diaphragm
Implementation Method 3
reintroducing them into the mainstream flow to minimize losses and enhance steam blanketing
Data Source
AI summary
This application provides controlled tip balance slits (200) for turbines. An example leakage flow control system (110) for a turbine may include a flow runner (150) with a tip shroud (152), a diaphragm or a guide blade (130), an extension ring (160) coupled to the diaphragm and positioned adjacent to the tip shroud (152), and a tip balance slit (200).