Gas Turbine Flow-Path Steps for Combustor Bow Wave Control
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Solution Overview
Problem
Conventional gas turbine engines experience bow wave effects at the interface between the combustor and turbine sections, leading to undesirable pressure variations and increased component temperatures, which degrade engine durability and performance.
Innovation Solution
Implementing a forward-facing step on the inner and/or outer bands of the turbine section adjacent the combustion section to create a stagnation region, increasing static pressure and preventing airflow reversal, thereby reducing bow wave formation and ingestion of combustion gases into cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional interface between combustor and turbine is used, then the structure is simple, but bow wave effects cause pressure variations and increased component temperatures that degrade durability and performance
Solution Approach 1:
The interface structure is segmented into multiple functional zones: a first cavity region, a second cavity region, and a throat region connecting them. This segmentation allows each zone to perform specific functions in managing the combustion gases and pressure waves, improving durability through controlled flow management while maintaining reasonable structural complexity
Solution Approach 2:
The patent introduces an intermediary throat region between the two cavity regions that acts as a mediator to manage the transition of combustion gases. This intermediary structure helps control pressure variations and reduce bow wave effects by providing a controlled passage that manages the interaction between different flow regions
2Reliability
If the interface structure is simplified, then manufacturing is easier, but pressure variations cause combustion gases to heat undesirable components, decreasing engine durability
Solution Approach 1:
The interface structure implements local quality by creating distinct regions with different geometric properties: expanded cavity regions for pressure management and a constricted throat region for flow control. This localized variation in structure allows specific areas to address temperature control needs while keeping other areas simpler for manufacturing
3Productivity
If bow wave effects are not addressed, then the structure remains simple, but pressure variations cause non-uniform pressure distribution that heats undesirable components and decreases performance
Solution Approach 1:
The interface is divided into segmented regions (first cavity, second cavity, throat) that work together to manage pressure distribution. This segmentation creates a more complex structure that actively manages bow wave effects to improve engine performance through better pressure control and reduced thermal loading on components
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
Prevents the ingestion of hot gases into engine components, reducing the need for additional cooling and enhancing the durability and performance of the turbine engine by maintaining lower component temperatures.
Implementation Method 1
Implementing a forward-facing step on the inner and/or outer bands of the turbine section adjacent the combustion section to create a stagnation region, increasing static pressure and preventing airflow reversal
Data Source
AI summary
A gas turbine engine includes a compressor section, a combustion section including an inner liner and an outer liner spaced from the inner liner, and a turbine section. The inner liner and outer liner at least partially define a combustion chamber. The turbine section includes an inner band extending between an upstream side and a downstream side opposite the upstream side and an outer band spaced from the inner band and extending between the upstream side and the downstream. The inner band and outer band at least partially define a working gas flow path. One or both of the inner band and the outer band include a step portion adjacent the upstream side and a body portion extending from the step portion to the downstream side. The step portion extends in a radial direction past the body portion.