Variable Watt Density Heaters for Gas Turbine Ice Protection

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Solution Overview

Problem

Gas turbine engines in aerospace applications face the risk of ice accretion on engine components, which can cause damage when ice breaks loose and is ingested, and existing ice protection systems consume high power.

Innovation Solution

An ice protection system with electrically-powered heaters of varying Watt densities embedded along a gas turbine structural member, with the highest density at the leading edge and lower densities downstream, allowing for continuous power at the leading edge and cyclical power to downstream heaters to minimize ice formation and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional uniform Watt density heaters are used along the engine inlet structural member, then ice protection coverage is provided, but power consumption is high

Engineering Contradiction:

Improveice protection coverageVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by varying the Watt density of heaters along the length of the structural member. The leading edge region, which experiences the highest cooling coefficients and greatest ice accretion risk, receives higher Watt density heating. Downstream regions with lower cooling coefficients receive progressively lower Watt density. This localized differentiation provides effective ice protection where needed while reducing power consumption in regions requiring less protection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heating system is segmented into multiple heater zones along the structural member, each with independently controlled Watt density. This segmentation allows the system to address different thermal protection requirements at different locations, optimizing the balance between ice protection effectiveness and power consumption by treating each segment according to its specific cooling coefficient characteristics.

Inventive Principle:

Principle #1Segmentation

2Reliability

If higher Watt density heaters are used throughout the structural member, then ice formation is more effectively prevented, but power expenditure increases

Engineering Contradiction:

Improveice formation preventionVSAvoidpower expenditure

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent implements local quality by matching heater Watt density to the local cooling coefficient at each position along the structural member. Regions with high cooling coefficients (leading edge) receive high Watt density to effectively prevent ice formation. Regions with lower cooling coefficients (downstream) receive lower Watt density. This approach maintains reliable ice formation prevention where aerodynamic conditions demand it while minimizing power expenditure in regions where less heating is required.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system changes the Watt density parameter along the length of the structural member based on the cooling coefficient distribution. By varying this key parameter to match local thermal conditions, the system achieves effective ice protection at minimum power expenditure, avoiding the waste of applying uniform high Watt density throughout the entire structure.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If heaters are embedded in the structural member, then protection from foreign object damage is provided, but manufacturing complexity increases

Engineering Contradiction:

Improveforeign object damage resistanceVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The heater elements are embedded within the structural member, nesting the heating system inside the existing airfoil structure. This nesting approach provides foreign object damage protection for the heaters while utilizing the structural member itself as the housing. The manufacturing complexity is managed by integrating the heater embedding process into the airfoil fabrication sequence, where heaters are positioned and secured within the structural member during manufacturing.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

Effectively reduces ice formation on gas turbine engine components while maintaining low power expenditure, providing efficient and continuous ice protection with reduced risk of foreign object damage.

Implementation Method 1

The first, second and third heaters are electrically-powered to prevent icing of the gas turbine structural member

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS8334486B2Engine inlet ice protection system having embedded variable watt density heaters

Publication Date: 2012.12.18 RTX CORP

AI summary

A system includes a first heater located at the leading edge of a gas turbine structural member, a second heater located aft of the first heater, and a third heater located aft of the second heater. The first, second and third heaters are electrically-powered to prevent icing of the gas turbine structural member. Each of the heaters has a Watt density, and the Watt densities of the heaters differ from one another as a function of a magnitude of a cooling coefficient for airflow passing the vicinity of each heater.