Compressor Aerofoil Tip Squealer Design for Leakage Reduction
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Solution Overview
Problem
The efficiency of gas turbine compressors is reduced due to over-tip leakage of working gases, which causes aerodynamic losses due to viscous interaction within the tip gap and with the mainstream flow, necessitating an aerofoil design that minimizes these losses.
Innovation Solution
A compressor aerofoil design featuring a tip portion that narrows to form a squealer, with a shoulder and transition region that reduces the tip leakage mass flow, thereby diminishing the interaction with the mainstream flow, and includes specific geometric features such as inflexion lines and angles to minimize aerodynamic losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the radial tip gap is reduced to minimize over tip leakage, then aerodynamic losses are reduced, but the risk of rubbing between rotor and stator components increases
Solution Approach 1:
The tip of the aerofoil is segmented into distinct functional zones: a squealer section with reduced thickness, a shoulder region, and a transition zone. This segmentation allows different portions of the tip to serve different purposes - the squealer minimizes leakage while the shoulder provides structural clearance, resolving the contradiction between reducing aerodynamic losses and preventing rubbing.
Solution Approach 2:
The aerofoil tip employs local quality variations through the squealer design, where the local thickness is reduced at the tip region compared to the main body. This localized modification optimizes the tip gap characteristics for reduced leakage without compromising the overall structural integrity and clearance requirements of the blade.
2Productivity
If the tip leakage mass flow is reduced through aerofoil design, then compressor efficiency is improved, but the design complexity of the aerofoil increases
Solution Approach 1:
The squealer design introduces dynamic flow control at the tip region. The reduced thickness and specific geometry of the squealer section create favorable flow patterns that actively manage the leakage flow, reducing its mass flow rate and detrimental effects on compressor efficiency while maintaining a relatively simple overall aerofoil structure.
Solution Approach 2:
The invention modifies key geometric parameters of the aerofoil tip, specifically the thickness distribution and the shape of the tip section. By changing these parameters to create the squealer-shoulder-transition structure, the design achieves reduced tip leakage and improved efficiency without requiring fundamentally complex design approaches.
Data Source
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AI summary
A compressor aerofoil (70) for a turbine engine. The compressor aerofoil (70) comprises a tip portion (100) comprising a tip wall (106) which extends from the aerofoil leading edge (76) to the aerofoil trailing edge (78). The tip wall (106) defines a squealer (110) which extends between the leading edge (76) the trailing edge (78). A shoulder (104, 105) is provided on one of the suction surface wall (88) or pressure surface wall (90) which extends between the leading edge (76) and the trailing (78). A transition region (108) tapers from the shoulder (104) in a direction towards the tip wall (106). The other of the suction surface wall (88) or pressure surface wall (90) extends towards the tip wall (106).