Duplex Turbine Nozzle Cooling Air Distribution
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Solution Overview
Problem
The existing gas turbine engines face inefficiencies due to the differential temperature patterns of hot and cold streaks in combustion gases, which lead to uneven heat loads on turbine nozzle vanes and blades, resulting in suboptimal performance and increased cooling air usage from the compressor.
Innovation Solution
A duplex turbine nozzle design with alternating vanes and distinct cooling patterns in inboard and outboard passages, where the number of vanes is twice that of fuel injectors, allowing for preferential cooling of hot and cold streaks by aligning fuel injectors with outboard passages and maintaining inboard passages between them, thereby optimizing cooling air distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional uniform nozzle vanes are used, then manufacturing simplicity is maintained, but thermal stress and cooling air requirements increase due to uneven heat loads from hot and cold streaks
Solution Approach 1:
The nozzle vanes are configured with different cooling hole patterns in different circumferential locations. Outboard passages (exposed to hot streaks) have higher cooling hole density while inboard passages (exposed to cold streaks) have lower cooling hole density, matching cooling provision to local heat load conditions and reducing overall thermal stress
Solution Approach 2:
The nozzle is divided into multiple passages with distinct cooling characteristics. Each passage is independently configured with appropriate cooling holes, allowing differentiated thermal management across the nozzle structure rather than uniform cooling throughout
2Strength
If increased cooling air is used, then thermal stress on turbine components is reduced, but compressor efficiency decreases due to reduced air available for combustion
Solution Approach 1:
Cooling holes are selectively distributed based on local heat exposure. Outboard passages receiving hot streaks receive concentrated cooling air while inboard passages receiving cold streaks receive minimal or no cooling air, optimizing the use of limited cooling air resources to protect critical areas without unnecessarily consuming compressor air
Solution Approach 2:
The cooling hole density parameter is varied across different passages. By changing the distribution parameter of cooling holes rather than using uniform density, the system achieves effective thermal protection where needed while minimizing total cooling air consumption
3Strength
If uniform cooling is applied to all passages, then manufacturing simplicity is maintained, but thermal stress reduction is suboptimal due to varying heat loads in different passages
Solution Approach 1:
Different cooling hole patterns are implemented in different passages based on their thermal environment. Outboard passages have denser cooling patterns while inboard passages have sparser patterns, matching manufacturing complexity to the actual thermal protection needs of each location
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 design enhances the durability of turbine components by reducing thermal stress and improving engine efficiency by better matching cooling air with heat loads, allowing for reduced compressor air usage and improved temperature profile management.
Implementation Method 1
The vanes have different patterns of film cooling holes with larger cooling flow density along the outboard passages than along the inboard passages
Data Source
AI summary
A duplex turbine nozzle includes a row of different first and second vanes alternating circumferentially between radially outer and inner bands in vane doublets having axial splitlines therebetween. The vanes have opposite pressure and suction sides spaced apart in each doublet to define an inboard flow passage therebetween, and corresponding outboard flow passages between doublets. The vanes have different patterns of film cooling holes with larger cooling flow density along the outboard passages than along the inboard passages.