Glow Plug Igniter Radial Gap Design for Gas Turbine Reliability

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Solution Overview

Problem

Spark plugs in gas turbine engines face reliability issues in wet conditions and low temperatures, and are costly, necessitating an alternative ignition solution that improves performance and durability.

Innovation Solution

A glow plug-based igniter system with a heater rod and a sleeve design, where the sleeve extends circumferentially around the heater rod to create a radial gap, enhancing ignition reliability and adaptability to various conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spark plugs are used for ignition in gas turbine engines, then ignition function is provided, but reliability deteriorates in wet conditions and low temperatures

Engineering Contradiction:

Improveignition reliabilityVSAvoidwet conditions and low temperatures

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the spark plug (electrical discharge mechanism) with a glow plug-based igniter (thermal heating mechanism). The glow plug heater rod generates heat through resistive heating to ignite the fuel-air mixture, eliminating the electrical spark mechanism that fails in wet and cold conditions. This substitution of the ignition physics fundamentally resolves the reliability issue in adverse environmental conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the ignition approach from electrical discharge to thermal heating by introducing a heated surface (glow plug heater rod). The heater rod is heated to a temperature sufficient to ignite the fuel-air mixture through thermal conduction and radiation, rather than relying on electrical breakdown. This parameter change in the ignition mechanism enables reliable operation in wet and cold conditions where electrical sparks fail.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If spark plugs are used for ignition, then ignition function is provided, but cost increases

Engineering Contradiction:

Improveignition functionVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a glow plug heater rod that can be manufactured from relatively inexpensive materials compared to spark plugs. The heater rod is designed to be cost-effective while providing reliable ignition. The use of standard thermal heating components rather than specialized electrical discharge components reduces manufacturing cost while maintaining ignition reliability.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By replacing the spark plug system with a thermal heating system using a glow plug heater rod, the patent reduces component cost. The heater rod can be manufactured from conventional thermal-resistant materials rather than requiring the precision engineering and specialized coatings of spark plugs, thereby reducing manufacturing cost while maintaining reliable ignition function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a sleeve is added around the heater rod to create a gap, then ignition reliability improves, but device complexity increases

Engineering Contradiction:

Improveignition consistencyVSAvoidstructure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the igniter into distinct functional segments: the base, the glow plug heater rod, and the sleeve with gap. The sleeve is separated from the heater rod by a radial gap, creating distinct functional zones. This segmentation allows the sleeve to serve as a protective and flow-controlling element while the heater rod provides thermal heating, improving reliability without excessive complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sleeve acts as an intermediary component between the heater rod and the surrounding combustion environment. It provides a controlled gap that regulates fluid flow around the heater rod, protecting the ignition zone from excessive cooling while allowing necessary air-fuel mixture access. This intermediary element improves ignition consistency by mediating the thermal and flow conditions without requiring complex control systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 glow plug-based igniter system provides improved reliability and adaptability, ensuring consistent ignition performance even in adverse conditions and reducing costs by leveraging off-the-shelf components with an adapter for specific gas turbine engine applications.

Implementation Method 1

igniting the mixture of the air and the fuel with the heating section of the heater rod

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11268486B2Igniter for gas turbine engine

Publication Date: 2022.03.08 PRATT & WHITNEY CANADA CORP

AI summary

There is disclosed an igniter for a gas turbine engine including: a base, a glow plug heater rod, the glow plug heater rod extending from the base along an axis and terminating in a rod end, a sleeve extending circumferentially around the glow plug heater rod along at least a portion of a length of the glow plug heater rod, the sleeve having an inner surface spaced from the glow plug heater rod to provide a gap between the inner surface and the glow plug heater rod, the gap extending radially relative to said axis.