Variable Guide Vane Actuation for Axial Compressor Surge Prevention
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Solution Overview
Problem
In gas turbines with axial-flow compressors, existing variable guide vane systems often experience non-proportional operation during startup and shutdown, leading to inefficient flow control and potential surge issues due to synchronized movement of all stages, which can result in inadequate compression and flow reversal.
Innovation Solution
A mechanism featuring a sprung pushrod lever with a spring and a mechanical stop allows differential angular movement of the first stage relative to other stages, enabling disproportionate longitudinal movement of levers connected to the unison ring, thereby allowing higher angular rotation of the first stage and smaller rotations of subsequent stages, and includes a bell crank system for actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all stages move synchronously during startup and shutdown, then the structure is simple and operation is easy, but flow control is inefficient and surge issues occur
Solution Approach 1:
The patent segments the variable guide vane system into multiple stages, allowing the first stage to be controlled independently from the second and third stages. This is achieved through separate control linkages: the first stage is controlled by a first control linkage, while the second and third stages are controlled by a second control linkage. This segmentation enables differential movement during startup and shutdown, improving start reliability by preventing surge conditions while maintaining reasonable structural complexity.
2Reliability
If the first stage is held constant during initial operation, then surge is prevented and flow control is improved, but the mechanism becomes more complex
Solution Approach 1:
The patent implements dynamic control of the first stage variable guide vanes during startup and shutdown operations. The first control linkage is designed to hold the first stage at a constant position during initial operation to prevent surge, while allowing it to move with the other stages during normal operation. This dynamic behavior adaptively responds to different operational phases, improving reliability without requiring overly complex manual operation procedures.
3Reliability
If disproportionate longitudinal movement is applied to the first stage lever, then angular rotation is optimized for surge prevention, but the linkage mechanism becomes more complex
Solution Approach 1:
The patent applies local quality by giving the first stage lever (first lever) different characteristics from the other stage levers. The first lever is configured to perform disproportionate longitudinal movement relative to the bell crank rotation, while the second and third levers move proportionally. This localized differentiation optimizes the angular rotation of the first stage for surge prevention during startup, while keeping the overall linkage mechanism relatively simple through the use of a common bell crank for all stages.
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 enhances start reliability and prevents surge by maintaining the first stage constant during initial operation, allowing proportional movement of other stages, thus improving flow control and reducing the likelihood of surge events during engine startup and shutdown.
Implementation Method 1
A mechanism featuring a sprung pushrod lever with a spring and a mechanical stop allows differential angular movement of the first stage relative to other stages
Implementation Method 2
a bell crank system for actuation
Data Source
AI summary
A device, system, or method to position variable guide vanes disproportionately is provided. An adjusting device for guide vanes of an axial-flow machine, includes a plurality of rotatably mounted rings of variable guide vanes, a plurality of levers which are arranged on the outer sides of a guide vane carrier for rotating the variable guide vanes, a plurality of adjusting rings, each of the adjustment rings is arranged coaxially to the guide vane carrier and to which a first end of one of the levers is connected, and an adjusting drive with which the adjusting rings may be moved in the peripheral direction. At least one of the levers is set up to perform at least partly a disproportionate longitudinal movement of the first end of the at least one lever.