Turbine Blade Tip Squealer Pocket Vortex Control
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Solution Overview
Problem
Gas turbine engines face efficiency reductions due to flow disturbances caused by leakage airflows at the tip of rotor blades, which existing methods have not adequately addressed without adding significant mass or compromising operational speeds and temperatures.
Innovation Solution
A rotor blade design with a changing stagger angle and chord along its length, featuring a squealer pocket with cooling openings and an optional tip shelf, which alters the local pressure distribution to reduce mixing losses from leakage airflows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a shroud is attached to the tips of the rotor blades, then the vortex induced losses are reduced, but the mass of the rotor increases significantly, which may limit rotor operational speeds and temperatures
Solution Approach 1:
The invention extracts the tip leakage flow from the main airflow path by creating a separate squealer pocket cavity at the blade tip. The leakage flow is diverted into this pocket where it can mix and dissipate separately, preventing it from interfering with the main suction side flow. This extraction approach reduces vortex induced losses without requiring a shroud attachment that would increase rotor mass.
Solution Approach 2:
The invention moves the leakage flow problem from the two-dimensional blade surface to a three-dimensional cavity structure. By creating the squealer pocket that extends into the blade thickness, the leakage flow is given a separate spatial dimension to mix and dissipate, isolating it from the main flow path and reducing its detrimental effects without adding external shroud structures.
2Loss of energy
If the clearance gap is decreased by reducing tolerances, then the leakage airflow is reduced, but the tolerances must still account for thermal and centrifugal expansion of materials to prevent interference
Solution Approach 1:
Instead of trying to prevent tip leakage flow, the invention accepts it as inevitable and converts this harmful leakage flow into a beneficial feature by directing it into the squealer pocket. The pocket allows the leakage flow to mix and dissipate in a controlled manner, transforming what was previously a loss mechanism into a design feature that protects the main flow path from contamination.
3Productivity
If the stagger angle changes along the airfoil length, then the flow distribution is optimized, but the manufacturing complexity increases
Solution Approach 1:
The invention applies local quality by creating the squealer pocket feature specifically at the blade tip region where tip leakage occurs, rather than modifying the entire blade structure. The varying stagger angle is also applied locally to optimize flow at critical regions. These localized modifications minimize the impact on overall manufacturing complexity while achieving significant performance benefits at the problem area.
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 design effectively reduces flow disturbances and increases turbine efficiency by maintaining a favorable pressure distribution at the tip, without altering the amount of leakage flow, thus enhancing operational performance.
Implementation Method 1
a plurality of cooling openings are in fluid communication with a source of cooling air, and deliver the cooling air to the squealer pocket
Implementation Method 2
a first surface of the wall has a convex configuration with respect to the pressure side of the airfoil as it extends from a leading edge to a trailing edge of the airfoil
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A rotor blade (32) for a gas turbine engine (10) is provided. The rotor blade having: an attachment (34); an airfoil (36) extending from the attachment to a tip (46); and a squealer pocket (200) located in a surface of the tip, wherein the squealer pocket is at least partially surrounded by a first surface (206) of a wall (202) located between the squealer pocket and a pressure side of the airfoil, wherein the first surface of the wall has a convex configuration with respect to the pressure side of the airfoil as it extends from a leading edge (38) to a trailing edge (40) of the airfoil.