Turbine Blade Cooling Air Control via Rotor Heat Shield Apertures
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Solution Overview
Problem
Existing gas turbine systems face challenges in controlling the delivery of cooling air to turbine blades, particularly in maintaining the necessary pressure balance to prevent hot gas leakage into cooling cavities while avoiding excessive cooling air flow into the hot gas path, especially when air is supplied to multiple blade rows from a single source.
Innovation Solution
The apparatus includes rotor heat shield elements with contoured root portions and radial portions that define a passage for cooling air, along with lock plates and seals to control pressure drops and airflow between cavities, ensuring optimal pressure balance and minimizing leaks by using apertures and seals to manage cooling air distribution between adjacent blade rows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air pressure is increased to prevent hot gas leakage into cooling cavities, then protection of rotor material is improved, but excessive cooling air flow into the hot gas path occurs which reduces efficiency
Solution Approach 1:
The cooling air delivery system is segmented into multiple controlled zones using rotor heat shield elements with individual cavities for each blade row. Each cavity can be independently pressure-controlled through precisely positioned openings in the radial portions of shield elements and lock plates, allowing optimized cooling air distribution to different blade rows without excessive flow into the hot gas path.
Solution Approach 2:
The rotor heat shield elements feature locally varied opening configurations in their radial portions, with each opening positioned to control cooling air delivery to specific blade rows. This local quality variation enables precise pressure balance at each location, ensuring adequate protection where needed while minimizing unnecessary cooling air consumption in other areas.
2Device complexity
If cooling air is supplied to multiple blade rows from a single source, then system complexity is reduced, but precise pressure control for each blade row becomes difficult
Solution Approach 1:
Rotor heat shield elements act as intermediary components between the single cooling air source and multiple blade rows. These shields with their precisely positioned openings in radial portions serve as flow distributors that automatically balance pressure across multiple cavities, achieving precise pressure control for each blade row while maintaining a simple single-source supply system.
Solution Approach 2:
The rotor heat shield elements perform self-regulating pressure distribution through their geometric design. The openings in the radial portions are positioned and sized to create automatic pressure balance, where the system self-adjusts cooling air flow to each cavity based on local pressure conditions without requiring external control mechanisms.
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 solution allows for controlled and efficient delivery of cooling air, maintaining pressure within the desired range of 100-150% of hot gas pressure, effectively preventing hot gas leakage into cooling cavities and reducing cooling air flow into the hot gas path, thus enhancing the protection of rotor materials and improving gas turbine efficiency.
Implementation Method 1
pressure drop along the different portions of the rotor heat shield passage can be controlled so as to ensure optimum local balance with the pressure of the hot gas
Implementation Method 2
at least one of said radial portion of the rotor shield elements and the lock plates includes at least one opening for controlled flow of cooling air
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An apparatus for controlled delivery of cooling air to turbine blades (5) in a gas turbine (1) including a rotor unit (4), at least a first and second row of turbine blades (5), a plurality of rotor heat shield elements (23) disposed in a circumferential row between the first and second rows of turbine blades (5) and configured to define with said rotor unit (4) a rotor heat shield passage (33, 34, 35, 36) that is fed with cooling air, and a plurality of lock plates (41, 42, 43) disposed in a circumferential row and configured to secure at least one of said first and second rows (6, 7, 8) of turbine blades (5) to the rotor unit (4), wherein a radial portion (28) of the rotor shield elements (23) and/or the lock plates (41, 42, 43) include at least one opening (49) for controlled flow of cooling air.