Gas Turbine Transition Duct Curved Guide Face Design
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Solution Overview
Problem
In gas turbines, cavities between modules allow combustion gas entrainment, reducing efficiency and increasing temperature of inner parts, which existing methods like knife edge seals and labyrinth structures fail to adequately address without complicating maintenance or reducing efficiency.
Innovation Solution
The design includes upstream and downstream members formed on both inner and outer sides of the passage in the radial direction, with curved and guide faces to reduce combustion gas inflow into cavities, preventing narrowing of clearance and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clearance of the opening portion of the cavity is made small to prevent combustion gas from entering the cavity, then the inflow of combustion gas is reduced, but the end portions of the shrouds of the vanes and the end portions of the platforms of the blades may come in contact due to thermal expansion
Solution Approach 1:
The invention applies a curved surface configuration to the downstream side member (vane or blade) that faces the cavity. Specifically, the surface extending from the opening portion of the cavity toward the downstream side is formed as a curved surface rather than a flat surface. This curvature allows the member to accommodate thermal expansion while maintaining the clearance and preventing combustion gas from entering the cavity, thus resolving the contradiction between reducing gas inflow and preventing contact during thermal expansion.
2Loss of energy
If the clearance of the opening portion is narrowed by installing a knife edge seal to prevent combustion gas entrainment, then the inflow of combustion gas is reduced, but the structure becomes complicated and maintenance frequency increases
Solution Approach 1:
The invention replaces complex seal structures (such as knife edge seals) with a simple curved surface configuration on the downstream side member. This curved surface naturally guides the combustion gas flow and prevents it from entering the cavity without requiring additional sealing components. The result is a structure that is both simple to manufacture and maintain, while effectively preventing combustion gas entrainment.
3Temperature
If the flow rate of cooling air is increased to suppress the rise in temperature of inner parts, then the temperature of turbine disc is reduced, but the cooling air mixed in the combustion gas increases which decreases the efficiency of gas turbine
Solution Approach 1:
The invention extracts or removes the source of the problem by preventing combustion gas from entering the cavity in the first place. By configuring the downstream side member with a curved surface that blocks the opening portion of the cavity, the invention eliminates the need for additional cooling air to compensate for hot combustion gas intrusion. This maintains turbine disc temperature within acceptable limits without the penalty of reduced efficiency from excessive cooling air mixing.
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
This configuration effectively reduces combustion gas inflow into cavities, preventing temperature increases and maintaining gas turbine efficiency without increasing cooling air flow rates or complicating maintenance.
Implementation Method 1
a downstream side member (43, 44) which defines the cavity (C1, C2) with the upstream side member (23), and has a curved surface extending from an opening portion (K) of the cavity toward the upstream side
Data Source
Figure 1
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Figure 3
AI summary
A gas turbine (1) includes downstream side members (43,44) that face a passage and have guide faces (43,d, 44d) arranged in the passage side as it goes toward the upstream side (22,23). In a cross section including an axis center of a rotor shaft extending in a flow direction of a gas main stream (Da), extension sections of the guide faces continuing to the upstream end portion of the guide faces (43d,44d) are arranged downstream from the cavity (C1,C2) inner wall portion (23b) of the upstream side member (22,23) facing the cavities (C1,C2).