Variable Vane Drive Device for Axial-Flow Compressor
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Solution Overview
Problem
In axial-flow compressors, thermal expansion differences between the casing and movable ring cause positional deviations, leading to uneven vane angles of variable vanes during startup and shutdown processes, affecting the operating state of the fluid machine.
Innovation Solution
The axial-flow fluid machine incorporates a variable vane drive device with a movable ring supported by multiple ring support mechanisms, including inner and outer rollers, which maintain contact and prevent positional deviations through a center distance adjustment mechanism, and a link mechanism to absorb bending, ensuring uniform vane angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the movable ring is supported by ring support mechanisms during startup and shutdown, then the structural support is improved, but thermal expansion differences cause positional deviations between the casing and movable ring axes
Solution Approach 1:
The patent introduces a center distance adjustment mechanism that dynamically modifies the geometric parameters of the ring support mechanism. By adjusting the center distance between the inner and outer rollers based on thermal expansion conditions, the mechanism compensates for dimensional changes in the casing, maintaining accurate positioning of the movable ring axis relative to the casing axis throughout temperature transitions.
Solution Approach 2:
The center distance adjustment mechanism functions as a feedback system that responds to thermal expansion differences between the casing and movable ring. The mechanism continuously adapts its configuration based on the relative positional changes caused by temperature variations, ensuring that the movable ring remains properly aligned with the casing axis despite thermal effects.
2Reliability
If the number of ring support mechanisms is increased to improve support stability, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent adopts a balanced approach by implementing a specific optimal number of ring support mechanisms (typically three or four) rather than using an excessive number. This partial action provides sufficient support stability and reliability for the movable ring while avoiding the increased complexity and cost associated with larger numbers of support mechanisms. The center distance adjustment mechanism further enhances the effectiveness of this optimized configuration.
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 configuration prevents axis positional deviations and maintains uniform vane angles regardless of the operating state, reducing unnecessary loads on the actuator and enhancing structural integrity by optimizing the number of ring support mechanisms.
Implementation Method 1
each of the plurality of ring support mechanisms includes: an inner roller disposed at an inner circumferential side of the movable ring; an outer roller which is disposed at an outer circumferential side of the movable ring
Implementation Method 2
a thermal expansion difference is generated between the casing and the movable ring due to a temperature difference between the casing which is in direct contact with the gas and the movable ring
Data Source
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AI summary
This variable stationary-blade driving device (30) is provided with an annular movable ring (31) disposed on the outer circumferential side of the casing (20) of an axial-flow compressor, four ring support mechanisms (40) disposed at an interval in the circumferential direction of the movable ring and for supporting the movable ring such that same can rotate around a rotor, and a link mechanism (70) for linking the movable ring with a variable stationary blade such that the orientation of the variable stationary blade changes with the rotation of the movable ring. The ring support mechanisms (40) each have an inner roller (41 i), an outer roller (41o), and a roller support base (43) for supporting the inner roller and the outer roller in a rotatable manner while the inner roller and the outer roller sandwich the movable ring.