Film Cooling Hole Diffuser Section Vortex Control
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Solution Overview
Problem
Current film cooling technologies face reduced effectiveness due to the counter rotating vortex pair Ω2, which causes cooling fluid to move away from the wall and mix with the main gas stream, leading to decreased film cooling performance over distance from the film cooling hole.
Innovation Solution
The design of film cooling holes with a diffuser section that generates anti-counter rotating vortex pairs and delta vortices, counteracting the counter rotating vortex pair Ω2, by using a delta vortex generator and a diffuser section with a V-shaped trailing edge and arched diffuser bottom, which enhances the film cooling effectiveness by reducing wall normal mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If film cooling holes are used to eject cooling fluid parallel to the main gas stream, then cooling fluid coverage is improved, but counter rotating vortex pair causes cooling fluid to move away from the wall and mix with main gas stream
Solution Approach 1:
The patent applies preliminary anti-action by introducing a vortex generator element that creates vortices opposite in direction to the harmful counter rotating vortex pair. This counter-vortex is generated in advance within the film cooling hole structure itself, before the cooling fluid exits, to preemptively counteract the adverse effects of the counter rotating vortex pair and maintain cooling fluid adherence to the wall surface.
Solution Approach 2:
The patent converts the harmful counter rotating vortex pair into a beneficial effect by utilizing the vortex generator to create controlled vortices that, while generated by the same flow conditions, act to reinforce cooling fluid attachment to the wall rather than cause detachment. The harmful vortex structure is transformed into a useful flow control mechanism through strategic geometric design of the film cooling hole outlet.
2Volume of moving object
If diffuser section is added to film cooling hole to broaden coverage, then spatial extension of cooling fluid is improved, but device complexity increases
Solution Approach 1:
The patent merges the vortex generator function with the diffuser section by integrating the vortex-generating geometry directly into the diffuser structure. The angled sidewalls of the diffuser section serve dual purposes: they broaden the spatial coverage of the cooling fluid while simultaneously generating the necessary vortices to counteract the counter rotating vortex pair. This consolidation reduces the number of separate components needed.
Solution Approach 2:
The diffuser section is designed to perform multiple functions simultaneously: it broadens the coverage area of the cooling fluid, generates counter-vortices to combat the harmful vortex pair, and maintains structural integrity within the turbine component. This multi-functionality reduces overall device complexity by eliminating the need for separate vortex generator elements.
3Area of stationary object
If film cooling holes are inclined to eject cooling fluid parallel to main gas stream, then cooling fluid coverage along the wall is improved, but cooling fluid mixes with main flow at higher blowing ratios
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a vortex generator that creates stabilizing vortices within the inclined film cooling hole structure. These pre-generated vortices counteract the tendency for flow separation that occurs at higher blowing ratios, allowing the cooling fluid to maintain its parallel trajectory along the wall surface for a longer distance before mixing with the main gas stream.
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 anti-counter rotating vortex pair and delta vortices increase the strength and spatial extension of the film cooling effect, improving the cooling fluid's adherence to the wall and reducing its mixing with the main flow, thereby enhancing film cooling effectiveness and maintaining coverage over a greater distance.
Implementation Method 1
The design of film cooling holes with a diffuser section that generates anti-counter rotating vortex pairs and delta vortices, counteracting the counter rotating vortex pair Ω2
Implementation Method 2
By doing so an isolating layer of a cooling fluid, for example comparably cool air, is applied to the turbine components' surfaces preventing a direct contact of hot working fluid with the turbine components
Implementation Method 3
Turbine components for example are usually cooled using thermal (convective) cooling in combination with thermal barrier coatings
Data Source
AI summary
A wall of a hot gas component includes a hot and a cold-gas sided surface, one film cooling hole extending from an inlet in the cold-gas sided surface to an outlet in the hot-gas sided surface and with a metering section of constant cross-section and a diffuser section extending from the metering section. The diffuser section is bordered by a diffuser bottom and two opposing diffuser side walls, has a leading region, which extends from the metering section to the outlet, lies opposite the diffuser bottom and has a constant cross-section over its entire length corresponding to an elongation of a leading region of the metering section up to the outlet. The diffuser section has two diffuser arms dividing the flow into two subflows, generating delta-vortices, a v-shaped outlet, and a v-shaped outlet opening.