Axial Compressor Blade Profile Design for Gap Tolerance
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Solution Overview
Problem
The radial gap between the tip of rotor blades or guide vanes and the duct wall in axial compressors of gas turbines increases over time, leading to disrupted flow and deterioration in aerodynamic performance, efficiency, and surge margin, especially at lower speeds.
Innovation Solution
The design of rotor blades and guide vanes with specific profile characteristics, including controlled metal angles, stacking angles, and front load angles, which minimize the disruption by optimizing the load distribution across the blade or vane element, particularly by localizing the absolute minimum and maximum front load angles near the tip, reducing the sensitivity to gap size changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the radial gap between blade tip and duct wall is allowed to increase over time, then the blade or vane element can be simpler in design, but the flow disruption increases and aerodynamic performance deteriorates
Solution Approach 1:
The blade profile is designed with non-uniform characteristics along its radial height, with specific metal angles and stacking angles optimized at different locations. The front load angle is specifically optimized to have a minimum in the region where gap effects are most critical, creating local quality variations that compensate for gap-induced flow disruption while maintaining overall design simplicity.
Solution Approach 2:
The invention changes the geometric parameters of the blade profile, specifically the metal angle, stacking angle, and front load angle, to optimize performance. By controlling these parameters to have specific distributions along the radial height, the design compensates for the harmful effects of radial gap expansion over time.
2Speed
If the radial gap increases at lower speeds of rotation, then the centrifugal force is reduced, but the gap-induced flow disruption becomes more significant and efficiency deteriorates
Solution Approach 1:
The blade profile incorporates local quality optimizations with specific metal angles and stacking angles at different radial positions. The front load angle minimum is positioned to address the specific flow disruption patterns that occur at lower rotational speeds when centrifugal forces are reduced and gap effects are amplified.
3Strength
If the gap size increases over operating time, then the blade or vane element experiences less mechanical stress, but the surge margin deteriorates and pumping stability decreases
Solution Approach 1:
The invention optimizes the geometric parameters including metal angle, stacking angle, and front load angle distribution along the radial height. These parameter changes are designed to maintain surge margin and pumping stability even as the radial gap increases over operating time, decoupling the mechanical stress reduction from the stability deterioration.
Data Source
AI summary
The present invention relates to an axial compressor for a gas turbine, in particular an aircraft engine, having at least one rotor blade or guide vane having a blade or vane element, which is arranged in a flow duct, and a leading edge and a trailing edge, which are joined to each other through a pressure side and a suction side, wherein, a new and novel profile section of the blade or vane element is provided.