Rotor Blade Tip Vortex Disruption via Slot Flow

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Solution Overview

Problem

Turbine rotor blades experience performance loss due to strong vortex flows on the suction side, resulting from over tip leakage and entropy generation, despite cooling mechanisms and squealer tip walls that minimize gap size between the airfoil tip and shroud.

Innovation Solution

The rotor blade design incorporates a tip cavity with a pressure side tip rail and a suction side tip rail, featuring a slot in the aft portion of the suction side rail that allows gas flow from the tip cavity, inhibiting vortex formation proximate to the suction side wall by disrupting the vortex flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a squealer tip wall is added to reduce the gap size between airfoil tip and shroud, then the gap size is reduced and hot gas leakage is minimized, but the device complexity increases and additional cooling mechanisms are required

Engineering Contradiction:

Improvehot gas leakageVSAvoidblade structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The tip structure is segmented into multiple functional components: the squealer tip wall for gap sealing, the tip floor for cooling medium distribution, and the tip cavity for vortex flow management. This segmentation allows each component to address specific problems independently while working together to reduce hot gas leakage without requiring excessive complexity in any single element.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A tip cavity is introduced as an intermediary space between the squealer tip wall and the blade interior. This cavity serves as a mediator that receives cooling medium from the blade interior and directs it to form vortex-cancelling flows at the tip region, thereby addressing the hot gas leakage problem without directly modifying the squealer tip wall structure itself.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If cooling holes are added in the tip floor to direct cooling medium to the tip cavity, then the cooling effectiveness is improved, but the device complexity increases

Engineering Contradiction:

Improvetip temperatureVSAvoidcooling system complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The tip floor serves multiple functions: it acts as a structural component closing the tip cavity, serves as a distribution manifold for cooling medium through integrated cooling holes, and functions as a flow control element directing coolant to the tip region. This multi-functionality reduces the need for separate dedicated cooling components, thereby improving cooling effectiveness without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The cooling holes are merged directly into the tip floor structure rather than being separate components. The tip floor combines structural support, cooling medium distribution, and flow direction functions into a single integrated element, reducing the number of discrete parts while achieving effective cooling of the tip region.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If the gap between airfoil tip and shroud is minimized, then hot gas leakage is reduced, but vortex flow formation on the suction side increases leading to entropy generation

Engineering Contradiction:

Improveenergy loss from hot gas leakageVSAvoidvortex flow and entropy generation

Core Design Contradiction:

Loss of energyVSObject-generated harmful factors

Solution Approach 1:

Cooling medium is directed into the tip cavity through the squealer tip wall and tip floor to create vortex-cancelling flows in advance, before hot gas leakage and vortex formation occur. This preliminary action of introducing counter-rotating flows prevents the formation of harmful vortices on the suction side, thereby reducing entropy generation while maintaining the minimized gap configuration.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The cooling medium, which could be considered a waste resource, is converted into a beneficial flow that cancels harmful vortices. By directing coolant through the tip cavity, the system transforms the potential waste of cooling fluid into a useful mechanism for eliminating vortex-induced entropy generation, thereby converting a potential harm into a benefit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 entropy generation and enhances performance by preventing vortex formation, thereby improving the efficiency of the turbomachine.

Implementation Method 1

Gas flows from the tip cavity via the slot and the opening, and the gas flow from the tip cavity inhibits formation of a vortex flow proximate to the suction side wall

Methodology Applied

Scientific EffectVortex flow disruption: Vortex Ring

Data Source

PatentUS10443405B2Rotor blade tip

Publication Date: 2019.10.15 GE INFRASTRUCTURE TECH LLC

AI summary

A rotor blade includes an airfoil. The airfoil includes a leading edge and a trailing edge downstream of the leading edge. The airfoil also includes a radially outer tip with a pressure side tip rail and a suction side tip rail. A slot is formed in an aft portion of the suction side tip rail and an opening is positioned between the suction side tip rail and the pressure side tip rail at the trailing edge. Gas flows from the tip via the slot and the opening to inhibit formation of a vortex flow proximate to the suction side of the airfoil.