Modulated Combustor Bypass for Gas Turbine Stability
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Solution Overview
Problem
Variable-area turbine engines face operational and efficiency issues due to changes in turbine flow area affecting the fuel-air factor of the combustor, leading to detrimental effects on combustor operation.
Innovation Solution
A gas turbine engine design incorporating a combustor bypass passage and valve system that diverts airflow around the combustor, adjusting the bypass airflow in response to changes in turbine flowpath area, maintaining an aerodynamically choked condition at the combustor inlet and stabilizing combustor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the turbine flow area is changed by adjusting turbine vane positions, then the turbine flow area is changed, but the fuel air factor of the combustor is affected detrimentally
Solution Approach 1:
A combustor bypass valve is introduced as an intermediary device to regulate airflow through a bypass passage. This valve acts as a mediator between the variable area turbine and the combustor, adjusting the bypass airflow in response to turbine flow area changes to maintain stable combustor operation and fuel air factor
Solution Approach 2:
The system changes the airflow parameter by diverting a portion of the airflow through the bypass passage. By dynamically adjusting the bypass valve position, the system modifies the airflow distribution to compensate for turbine vane position changes, maintaining consistent combustor conditions
2Area of moving object
If the turbine flow area is increased, then the turbine flow area increases, but the combustor inlet may become aerodynamically choked
Solution Approach 1:
The bypass valve is positioned and controlled in advance to prevent aerodynamic choking at the combustor inlet. By proactively adjusting the bypass airflow before choking occurs, the system maintains optimal airflow velocity through the combustor despite turbine area changes
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 ensures stable and efficient combustor operation by adjusting airflow through the bypass passage in response to changes in turbine flowpath area, maintaining combustor stability and efficiency even with varying turbine flow conditions.
Implementation Method 1
The combustor inlet may be configured to be in an aerodynamically choked state when the flowpath area of the variable area turbine is at a minimum area
Data Source
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AI summary
A combustor section (26) of a gas turbine engine (20) includes a combustor (56) having a combustor inlet (62), and a combustor bypass passage (64) having a passage inlet (66) located upstream of the combustor inlet. The combustor bypass passage is configured to divert a selected bypass airflow (70) around the combustor. A combustor bypass valve (72) is located at the combustor bypass passage to control the selected bypass airflow along the combustor bypass passage. A method of operating a gas turbine engine (20), includes urging a core airflow from a compressor section (24) toward a combustor section (26), flowing a first portion of the core airflow into the combustor section via a combustor inlet (62), and flowing a second portion of the core airflow into a combustor bypass passage (64) via a combustor bypass valve (72), thereby bypassing the combustor with the second portion of the core airflow.