Turbine Blade Tip Shelf Vortex Control
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Solution Overview
Problem
Gas turbine engines face efficiency reduction due to leakage airflows causing flow disturbances at the tip of rotor blades, with existing solutions either failing to adequately address the issue or adding significant mass through shrouds.
Innovation Solution
The design incorporates a rotor blade with a squealer pocket and/or tip shelf, featuring a changing stagger angle and chord, and a convex surface configuration to manage airflow, reducing leakage and vortex-induced losses without increasing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a shroud is attached to the tips of the rotor blades to reduce vortex induced losses, then the losses are reduced, but the mass of the rotor increases significantly
Solution Approach 1:
The invention extracts the vortex control function from a separate shroud component and integrates it into the rotor blade tip structure itself. The tip shelf and squealer pocket are formed as integral parts of the rotor blade, eliminating the need for an additional shroud component while maintaining vortex control functionality.
Solution Approach 2:
The invention merges the vortex control function with the rotor blade tip structure by integrating the tip shelf and squealer pocket features directly into the blade. This combines the structural support function of the blade tip with the flow control function previously requiring a separate shroud.
2Loss of energy
If the clearance gap is decreased by reducing tolerances between the tip of each rotor blade and the outer flowpath, then the leakage airflow is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The tip shelf is positioned upstream of the clearance gap and acts to pre-control the leakage airflow before it reaches the gap. This preliminary flow control reduces the dependence on tight clearance tolerances, allowing for more relaxed manufacturing specifications while still achieving reduced leakage losses.
Solution Approach 2:
The tip shelf acts as an intermediary structure between the main blade body and the clearance gap. It modifies the leakage flow path and reduces the direct impact of clearance variations on performance, serving as a buffer that decouples the relationship between clearance tolerance and energy loss.
3Productivity
If the stagger angle changes along the airfoil from base to tip, then the airflow distribution is improved, but the manufacturing complexity increases
Solution Approach 1:
The stagger angle is varied locally along the span of the airfoil, with different regions (base, transition, tip) having different angle characteristics. This localized variation optimizes airflow at each section while maintaining overall structural integrity and manufacturability.
Solution Approach 2:
The airfoil geometry transitions dynamically from the base to the tip through a defined transition region. The stagger angle and chord length change continuously along the span, creating a dynamic geometric progression that optimizes performance while following manufacturable transition curves.
Data Source
AI summary
A rotor blade for a gas turbine engine is provided. The rotor blade having: an attachment; an airfoil extending from the attachment to a tip; and a tip shelf located in a surface of the tip proximate to a pressure side of the airfoil, wherein the tip shelf has a ledge portion extending from the pressure side to a wall portion extending upwardly from the ledge portion to the tip and wherein the wall portion is configured to have a convex portion with respect to the pressure side of the airfoil as it extends from a leading edge to a trailing edge of the airfoil.