Adjustable Fan Tip Grooves for Distortion Tolerance

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Solution Overview

Problem

Gas turbine engines experience high distortion due to pressure gradients and swirl, leading to engine stall and undesirable aeromechanical behavior, which existing mitigation systems struggle to effectively address.

Innovation Solution

A fan case assembly with a plurality of rotatable drums and a control unit that adjusts the position of the drums between closed and open positions in response to preselected operating conditions, minimizing the negative effects of pressure and swirl distortions by controlling tip treatment on the fan blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fan with fixed tip treatment is used, then the structure is simple, but the engine cannot adapt to different operating conditions and distortion levels

Engineering Contradiction:

Improveadaptability to operating conditionsVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the tip treatment structure movable rather than fixed. The fan case includes a plurality of rotatable drums with grooves that can rotate between different positions to expose or cover the grooves, allowing the tip treatment to dynamically adapt to different operating conditions and distortion levels while maintaining a relatively simple base structure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The tip treatment is segmented into multiple independent drums rather than a single fixed structure. Each drum can be independently rotated to control the exposure of grooves, allowing localized adaptation to distortion patterns at different circumferential positions of the fan blades, thereby improving adaptability without requiring complete structural redesign.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If grooves are always open to the gas path, then distortion mitigation is maximized, but fan performance during normal operation deteriorates

Engineering Contradiction:

Improvedistortion effectsVSAvoidfan performance

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The grooves are designed to be dynamically controllable rather than permanently open. The rotatable drums can rotate to either expose the grooves to the gas path for distortion mitigation or cover the grooves to maintain optimal fan performance during normal operation, thus resolving the contradiction between distortion mitigation and productivity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs periodic activation of the groove exposure based on operating conditions. The control unit rotates the drums to expose grooves only when distortion is detected (such as during maneuvering or high-altitude operations), and covers them during normal cruise conditions, implementing a periodic action that balances distortion mitigation with fan performance.

Inventive Principle:

Principle #19Periodic action

3Manufacturing precision

If multiple sets of drums with different groove depths are used, then distortion mitigation precision is improved, but device complexity increases

Engineering Contradiction:

Improvedistortion mitigation precisionVSAvoidnumber of drums

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Different drums are designed with different groove depths tailored to specific distortion scenarios. The first set of drums has grooves extending to a first depth while the second set has grooves extending to a second depth, allowing localized optimization for different distortion patterns and operating conditions, thereby improving distortion mitigation precision without requiring all drums to be identical.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The drum array is segmented into multiple sets with different groove depths, each set positioned at specific circumferential locations. This segmentation allows the system to address different distortion patterns at different locations around the fan, improving overall distortion mitigation precision while keeping each individual drum relatively simple in design.

Inventive Principle:

Principle #1Segmentation

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

The solution effectively improves the stall margin of gas turbine engines by mitigating the effects of pressure and swirl distortions, enhancing engine performance and reducing the risk of engine stall.

Implementation Method 1

Each drum of the plurality of drums may be shaped to include at least one groove that extends partway into the drum... In the open position, at least one groove of the corresponding drum may face towards the gas path so that the at least one groove of the corresponding drum is open to the gas path to allow air to flow into the at least one groove from the gas path

Methodology Applied

Scientific EffectFluid flow redirection:

Data Source

PatentUS12286936B1Adjustable fan track liner with groove array active fan tip treatment for distortion tolerance

Publication Date: 2025.04.29 ROLLS ROYCE NORTH AMERICAN TECHNOLOGIES INC

AI summary

A gas turbine engine includes a fan and a fan case assembly. The fan includes a fan rotor configured to rotate about an axis of the gas turbine engine and a plurality of fan blades coupled to the fan rotor for rotation therewith. The fan case assembly extends circumferentially around the plurality of fan blades radially outward of the plurality of the fan blades.