Gas Turbine Blade Tip Contour for Reduced Tip Leakage
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Solution Overview
Problem
Gas turbine rotor blade tip leakage leads to inefficiencies, increased heat loads, and reduced blade life due to tip vortex generation and clearance, contributing to higher specific fuel consumption and engine cycle loss.
Innovation Solution
The rotor blade tip geometry is designed with a contour that shifts towards the suction side wall, featuring a maintained or contracted shape and offset contours to delay tip vortex generation, reducing leakage interaction and desensitizing the rotor to tip clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rotor blade tip clearance is reduced to minimize tip leakage, then tip leakage losses are reduced, but the rotor becomes more sensitive to manufacturing tolerances and thermal expansion
Solution Approach 1:
The patent applies local quality by creating a specific geometric feature at the blade tip region that differs from the rest of the blade. The tip geometry includes a rounded contour with a radius of curvature that is larger than the tip clearance, which locally modifies the flow characteristics at the critical tip region while leaving the rest of the blade structure unchanged. This localized geometric modification reduces tip leakage losses without affecting the overall blade manufacturing tolerances.
Solution Approach 2:
The patent implements preliminary action by pre-shaping the blade tip geometry during manufacturing to anticipate and compensate for thermal expansion and operational clearance changes. The rounded tip contour is designed in advance to maintain optimal clearance characteristics under various operating conditions, thereby reducing sensitivity to tip clearance variations during actual engine operation.
2Temperature
If cooling is increased to reduce heat loads at the blade tips, then blade temperature is reduced, but engine cycle loss increases
Solution Approach 1:
The patent converts the harmful tip leakage flow into a beneficial cooling mechanism. The rounded tip geometry is designed to promote the formation of a protective vortex that redirects the leakage flow to enhance cooling effectiveness at the blade tip region. This transforms the previously harmful leakage flow into a useful cooling resource, reducing blade tip temperatures without requiring additional cooling air and thereby avoiding increased engine cycle losses.
3Productivity
If the blade tip geometry is modified to delay vortex generation, then tip leakage interaction is reduced and stage efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies spheroidality by replacing the traditional sharp or flat blade tip geometry with a rounded contour. The tip is formed with a continuous curved surface characterized by a radius of curvature that is larger than the tip clearance. This simple curved geometry effectively delays vortex generation and reduces tip leakage interaction, improving stage efficiency while remaining relatively simple to manufacture compared to more complex geometric modifications.
Data Source
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AI summary
Systems and methods for a gas turbine engine include a rotor having a rotor blade that has a base, a tip, and an outer surface defined by a leading edge, a trailing edge, a suction side wall, and a pressure side wall, all extending between the base and the tip. Geometry of the tip of the rotor blade has a contour that is directed first toward the suction side wall at the leading edge, and then toward one of the pressure side wall or the suction side wall at the trailing edge. The geometry has a maintained or contracted shape that is shifted toward the suction side wall. The geometry is configured to reduce tip leakage interaction of the rotor to delay onset of tip vortex generation and desensitize the rotor to tip clearance.