Turbomachine Stator Vane Cooling Liner Design
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Solution Overview
Problem
Turbine vanes in turbomachines face high temperatures leading to reduced lifetime due to inefficient cooling, resulting in large temperature gradients and radial stresses, especially near the leading edge.
Innovation Solution
A turbomachine stator vane with a perforated open liner having specific distributions of holes to concentrate cooling air jets at the leading and trailing edges, reducing impacts on bridges and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is distributed uniformly through multiple perforations in the liner, then the cooling coverage is improved, but large temperature gradients and radial stresses appear locally (especially near the leading edge)
Solution Approach 1:
The liner incorporates two distinct series of perforations with different distributions: a first series concentrated at the leading edge and a second series at the trailing edge. This local differentiation allows each zone to receive optimized cooling air flow, reducing local temperature gradients and radial stresses while maintaining overall cooling coverage.
2Reliability
If cooling air flows through the annular cavity and exits through calibrated holes in the trailing edge, then a protective film is formed, but cooling efficiency at the leading edge is reduced
Solution Approach 1:
The cooling system is segmented into two independent perforation series: one dedicated to leading edge cooling and another to trailing edge cooling and protective film formation. This segmentation allows each zone to be optimized independently, with the first series providing direct cooling to the leading edge and the second series maintaining protective film formation at the trailing edge.
3Manufacturing precision
If the liner is rigidly secured to the vane, then assembly precision is improved, but thermal expansion stresses increase under high temperature conditions
Solution Approach 1:
The liner transitions from a rigid fixed connection to a dynamic system where it can slide axially within the vane. The guide zone at the bottom of the vane provides controlled movement space, allowing the liner to expand and contract thermally without generating excessive stresses, while maintaining proper positioning through gravitational and frictional forces.
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
Significantly reduces radial stresses and temperature gradients, achieving better temperature equilibrium and extending vane lifetime by up to 60°C improvement in temperature gradient over the pressure side face.
Implementation Method 1
the flow of cooling air delivered by a source of air under pressure, generally the compressor of the turbomachine, penetrates into the outer platform 14 via an inlet orifice 24, reaches the inside of the liner 18, and has a fraction thereof escape through the multiple perforations of the liner so as to from jets of air in the peripheral cavity 20 that cool the inside wall of the airfoil 12 by impact
Implementation Method 2
the liner being secured to the vane at one end and being free at another end to slide along an inside edge of the vane under the effects of relative thermal expansion between the liner and the inside wall of the vane
Implementation Method 3
escapes through calibrated holes 26 formed in the trailing edge or in the pressure side face of the airfoil, so as to form a protective film of air along said trailing edge
Data Source
AI summary
A turbomachine stator vane having a leading edge, a trailing edge, and pressure side and suction side faces, a first and a second series of a plurality of holes, calibrated emission holes, and a perforated open liner defining an annular cavity between an outside wall of the liner and an inside wall of the vane, an air opening for feeding cooling air to the inside of the liner, and an air exhaust opening for exhausting cooling air from the vane, the liner being secured to the vane at one end and being free at another end to slide along an inside edge of the vane under the effects of relative thermal expansion between the liner and the inside wall of the vane. The holes through the liner in the second series of holes are disposed to avoid any impact of the cooling air against the bridges of the vane.