Stator Heat Shield Cooling via Ribs and Baffles
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Solution Overview
Problem
The existing stator heat shields in gas turbines have limited lifetime due to exposure to hot gases, and there is a need for improved cooling methods to enhance their durability.
Innovation Solution
The integration of baffle plate cooling, convection cooling, and sealing element cooling techniques, along with the use of ribs, bores, and recesses, to effectively dissipate heat and reduce temperature burdens on the stator heat shields, thereby increasing their lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stator heat shields are exposed to hot gas to perform their protective function, then they can protect the housing and guide vane carriers, but their lifetime is reduced due to thermal exposure
Solution Approach 1:
The heat shield is divided into multiple segments arranged in a ring, with sealing elements at the interfaces. This segmentation allows for thermal expansion management while maintaining protective coverage, and the sealing elements prevent hot gas leakage that would otherwise accelerate degradation
Solution Approach 2:
A cooling gas path is introduced as an intermediary between the hot gas path and the heat shield interior. Cooling gas flows through channels within the heat shield, absorbing heat and preventing excessive temperature buildup that would reduce lifetime
2Duration of action of stationary object
If cooling gas is introduced to increase lifetime, then thermal exposure is reduced, but the structural complexity increases with additional cooling channels and sealing elements
Solution Approach 1:
The cooling channels serve multiple functions: they cool the heat shield, provide structural reinforcement through the rib structures, and the sealing elements simultaneously seal the cooling gas path and prevent hot gas intrusion. This multi-functionality reduces the need for separate components
Solution Approach 2:
The cooling channels are nested within the heat shield structure itself, with ribs forming the channel walls and the sealing elements integrated at the interfaces. This nested arrangement eliminates the need for separate external cooling systems
3Stability of the object's composition
If sealing elements are added to seal gaps between heat shield segments, then hot gas leakage is prevented, but the sealing elements themselves require cooling to maintain their sealing function
Solution Approach 1:
Cooling is applied locally at the sealing element locations through specifically positioned cooling channels and bores. This localized cooling ensures the sealing elements maintain their dimensional stability and sealing capability without requiring uniform cooling of the entire heat shield
Solution Approach 2:
The cooling system is designed to automatically supply cooling gas to the sealing elements through the bores and channels, maintaining their temperature and sealing function without external intervention. The system self-regulates to ensure sealing element longevity
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 combination of cooling methods results in improved heat distribution and reduced temperature exposure, leading to a longer lifetime of the stator heat shields by efficiently dissipating heat through convection and film cooling, even when the stator heat shields are offset.
Implementation Method 1
heat can be transmitted by convection from the stator heat shield to the respective baffle plate within the channels
Implementation Method 2
the inside of the respective stator heat shield facing away from the hot gas path is exposed to a suitable cooling gas to cool the respective stator heat shield
Implementation Method 3
The respective sealing element then engages in the aligned and flush grooves of the two end faces opposite one another in the gap, thereby sealing the gap and thus sealing the connection between the hot gas path facing the outside with a cooling gas path facing the inside
Implementation Method 4
Film cooling of the sealing elements and the end faces of the neighboring stator heat shields opposite one another in the gap can be achieved in the area of the gap
Data Source
AI summary
A stator heat shield (6) for a gas turbine (1) includes an outside (11) which in the installed state faces a hot gas path (9) of the gas turbine (1), and an inside (12) facing away from the outside (11). A plurality of ribs (13) are formed on the inside (12) and extend axially in the installed state with regard to an axis of rotation (8) of a rotor (3) of the gas turbine (1) and, in the circumferential direction, are spaced a distance apart from one another. At least one baffle plate (14) is arranged on the inside (12) and is in contact with the ribs (13). At least one groove (16) is designed in an end face (15) bordering the stator heat shield (6) in the circumferential direction, into which at least one sealing element (18) can be inserted. A plurality of bores (19) are included, each opening at a distance from the groove (16) in the direction of the outside (11) at the inside (12) at one end and on the end face (15) at the other end and arranged a distance apart from one another in the axial direction.