Compressor Rotor Airfoil Dihedral Distribution
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Solution Overview
Problem
In gas turbine engines, compressor rotor blades may experience plowing due to minimal lengthening under high velocity and thermal conditions, leading to reduced tip clearance and potential damage to both blades and shroud, which affects engine performance.
Innovation Solution
The design incorporates airfoils with opposed pressure and suction sides joined at chordally opposite leading and trailing edges, featuring a leading edge dihedral angle with a span-wise distribution that includes at least one inflection point, optimizing the sweep and lean angles to reduce rub angles and improve stall margin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the blade operates under high velocity and thermal conditions, then the blade may lengthen due to thermal expansion, but this causes reduced tip clearance and potential plowing into the shroud
Solution Approach 1:
The patent applies parameter changes by modifying the leading edge dihedral angle distribution along the blade span. This geometric parameter adjustment compensates for thermal expansion effects by optimizing the blade's initial configuration to maintain proper clearance under thermal loading conditions.
Solution Approach 2:
The patent implements preliminary action by pre-setting the leading edge dihedral angle distribution in the blade design before operation. This preliminary geometric configuration anticipates thermal expansion and positions the blade to maintain optimal tip clearance even when lengthening occurs under high temperature conditions.
2Reliability
If the leading edge dihedral angle is optimized with inflection points, then the stall margin is improved, but the design complexity increases
Solution Approach 1:
The patent applies local quality by introducing inflection points at specific locations along the leading edge dihedral angle distribution. Rather than uniformly modifying the entire airfoil geometry, the inflection points are strategically placed to locally optimize flow attachment and delay stall, improving reliability without excessively increasing overall design complexity.
Data Source
AI summary
A compressor rotor airfoil in a gas turbine engine is presented. Opposed pressure and suction sides are joined together at chordally opposite leading and trailing edges. The pressure and suction sides extend in a span direction from a root to a tip. A leading edge dihedral angle is defined at a point on the leading edge between a tangent to the airfoil and a vertical. The leading edge dihedral angle has a span-wise distribution. The distribution has at least one inflection point. A method of reducing a rub angle between a compressor rotor blade and a casing surrounding the blade is also presented.