Gas Turbine Compressor Blade Deflection for Ice Impact Tolerance

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Solution Overview

Problem

Gas turbine engines face significant challenges in protecting against ice accretion, particularly in geared turbofan architectures, where ice accretion severity and size are higher due to low speed and low hub stagger of the fan, leading to inefficiencies and damage when traditional methods like thicker blades or anti-icing systems are implemented.

Innovation Solution

Increasing the axial gaps between rotor and stator blades in the compressor stages to allow for blade deflection without touching adjacent stators, maintaining high efficiency and reducing the risk of damage from ice crystal impacts, rather than increasing blade thickness which would be detrimental to efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rotor blades are made thicker to withstand ice crystal impacts, then blade strength and damage resistance are improved, but blade weight increases and aerodynamic performance deteriorates

Engineering Contradiction:
Improveblade strengthVSAvoidaerodynamic performance
Core Design Contradiction:
StrengthVSProductivity

Solution Approach 1:

The patent applies dynamics by allowing the rotor blades to deflect dynamically in response to ice crystal impacts rather than resisting them with increased thickness. The blades are designed to move within acceptable limits during impact, absorbing the shock through controlled deflection rather than structural reinforcement, thereby maintaining aerodynamic efficiency while preventing damage.

Inventive Principle:
Principle #15Dynamics

2Object-affected harmful factors

If anti-icing systems with electrical heaters or hot air are provided for the vanes, then ice build-up prevention is improved, but system complexity and energy consumption increase

Engineering Contradiction:
Improveice build-up preventionVSAvoidsystem complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent converts the harmful effect of ice crystal impacts into a beneficial design criterion by allowing controlled blade deflection. Instead of using complex heating systems to prevent ice accumulation, the design accepts that ice crystals will impact the blades but ensures that the blades are designed to deflect safely, transforming the harmful impact into a manageable dynamic response that protects the engine without requiring additional anti-icing infrastructure.

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

3Object-affected harmful factors

If anti-icing systems with electrical heaters or hot air are provided for the vanes, then ice build-up prevention is improved, but energy consumption increases

Engineering Contradiction:
Improveice build-up preventionVSAvoidenergy consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent eliminates the need for energy-consuming anti-icing heating systems by redesigning the blade flexibility to accommodate ice crystal impacts. The harmful ice crystal impacts are converted into a design parameter where blades are allowed to deflect within safe limits, thereby preventing ice build-up without requiring additional thermal energy input from heaters or hot air systems.

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

Data Source

PatentEP3913192B1Gas turbine engine
Publication Date: 2024.03.13 ROLLS ROYCE PLC
  • EP3913192B1 patent drawingFigure 1~2
  • EP3913192B1 patent drawingFigure 3~4
  • EP3913192B1 patent drawing

AI summary

A gas turbine engine comprises a fan, a compressor, a combustor, and a turbine coupled to the compressor through a shaft, wherein the compressor comprises a first stage with respective rotor blades and stator vanes with a leading edge, a trailing edge and a tip, the blades and vanes being separated by axial gaps. A tip axial distance between the blade trailing edge of the first rotor and the vane leading edge of the first stator is equal to d×inlet flow function10, wherein d is equal or greater than 23 mm and less than 40 mm, and the inlet flow function is defined as dimensionless value of mTP, wherein m is a mass airflow at an inlet to the compressor in kg/s, T is the total temperature at the inlet to the compressor in K, and P is the total pressure at the inlet to the compressor in kPa at the compressor aerodynamic design point.