Turbomachine Blade Cooling Circuit Double Row Slots
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Solution Overview
Problem
The trailing edge of turbomachine blades is challenging to cool efficiently due to space constraints and the difficulty in installing turbulence promoters, leading to high thermal levels.
Innovation Solution
A moving turbomachine blade design featuring a cooling circuit with two rows of radially offset discharge slots along the trailing edge, allowing for enhanced cooling upstream of the usual slots and increased blade thickness for cavity installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single row of discharge slots is used at the trailing edge, then the blade structure remains simple, but the cooling efficiency of the trailing edge is insufficient
Solution Approach 1:
The single row of discharge slots is segmented into two distinct rows: a first row of discharge slots and a second row of discharge slots. The first row is configured to discharge cooling air onto the intrados face of the blade at the trailing edge, while the second row is configured to discharge cooling air onto the extrados face of the blade at the trailing edge. This segmentation allows simultaneous cooling of both faces, significantly improving cooling efficiency without excessive complexity.
Solution Approach 2:
The cooling circuit transitions from a single-dimensional cooling approach (one row of slots) to a two-dimensional cooling approach (two rows of slots discharging onto opposite faces). By adding the second row of discharge slots on the extrados face, the cooling coverage is expanded from one side to both sides of the blade trailing edge, effectively addressing the thermal challenges in this critical zone.
2Ease of manufacture
If the blade thickness is reduced to meet minimum requirements, then the blade can be manufactured with standard dimensions, but the space for installing cooling promoters and cavities is limited
Solution Approach 1:
The blade thickness is optimized locally at the trailing edge where the cooling circuits are positioned. The first and second discharge slots are arranged in this region to provide enhanced cooling coverage. By concentrating the cooling function in the trailing edge region with appropriate thickness, the blade maintains manufacturability while achieving superior cooling capability where it is most needed.
3Device complexity
If cooling air is discharged only at the trailing edge, then the cooling circuit is simpler, but the thermal level in the upstream area remains high
Solution Approach 1:
The discharge slots are segmented into two functional rows that work together to cool different regions. The first row addresses the intrados face cooling, while the second row addresses the extrados face cooling. This segmentation enables comprehensive cooling coverage including the upstream area, effectively reducing thermal levels without requiring a completely different cooling arrangement.
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 additional row of discharge slots improves cooling efficiency by increasing the curvilinear abscissa of the intrados face cooling and allowing for the installation of cooling promoters or separate cavities, thereby extending blade lifespan and reducing cooling flow requirements.
Implementation Method 1
pumping, and by film ('film cooling' in English) with an ejection almost tangent to the blade profile, which greatly increases its efficiency
Implementation Method 2
cooling air, which is generally introduced into the blade through its root, passes through it following a path formed by cavities made in the blade before being ejected through slots opening on the surface of the blade
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a turbomachine moving blade (2) comprising at least one cooling circuit comprising at least one cavity (16; 16a, 16b) extending radially between the foot and the vertex, at least one air intake opening at a radial end of the cavity, a plurality of first discharge slots (18) arranged to open out along the trailing edge between the foot and the vertex, and a plurality of second discharge slots (20) which are separate from the first discharge slots and provided along the trailing edge (14) between the foot and the vertex, the second discharge slots (20) being axially offset upstream from the first discharge slots (18) and each of the first discharge slots being radially offset from each of the second discharge slots, without any overlap between the first and second discharge slots.