Gas Turbine Exhaust Ejector Mixer Lobe Support

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Solution Overview

Problem

Existing exhaust ejector/mixers in gas turbine engines face challenges with thermal variations, radial deflection, and vibrations, which affect the stiffness and longevity of the surrounding hardware.

Innovation Solution

The design incorporates a cantilevered ejector/mixer with circumferentially distributed lobes and a support member featuring concave joint surfaces that engage with convex surfaces on the lobes, providing enhanced rigidity and accommodating thermal variations and vibrations by connecting all lobes together and allowing the support member to absorb displacements independently of the exhaust cone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the ejector/mixer is exposed to high and low velocity flows, then mixing performance is improved, but thermal variation and radial deflection increase

Engineering Contradiction:

Improvemixing performanceVSAvoidthermal variation and radial deflection

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the physical parameters of the ejector/mixer structure by introducing circumferential ribs and support members, which modify the structural stiffness and thermal response characteristics to accommodate thermal variation and radial deflection while maintaining mixing performance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent allows the ejector/mixer to dynamically respond to thermal and vibrational conditions by incorporating flexible support members and rib structures that can deflect and adapt to changing operational conditions, rather than relying on rigid fixed structures

Inventive Principle:

Principle #15Dynamics

2Reliability

If the ejector/mixer is exposed to high velocity flows, then mixing performance is improved, but vibrations increase

Engineering Contradiction:

Improvemixing performanceVSAvoidvibrations

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent incorporates support members and rib structures that act as pre-designed vibration dampers, cushioning the ejector/mixer against vibrations generated during high velocity flow operation before the vibrations can cause harmful effects to surrounding hardware

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If the exhaust case stiffness is increased, then radial deflection is reduced, but device complexity increases

Engineering Contradiction:

Improveradial deflectionVSAvoidexhaust case structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent segments the ejector/mixer structure into multiple functional elements including circumferential ribs, support members, and lobe structures, each contributing to overall stiffness and stability while allowing modular design and manufacturing that manages complexity

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10619596B2Gas turbine engine exhaust ejector/mixer

Publication Date: 2020.04.14 PRATT & WHITNEY CANADA CORP

AI summary

An ejector/mixer for a gas turbine engine includes an annular wall having upstream end adapted to be fastened to an engine case and a downstream end forming a plurality of lobes. A support member interconnects the lobes, and includes an annular blade located radially inwardly of the bight of the lobes. The lobes extend radially inwardly downstream relative to the annular wall and the support member includes an annular blade and has spaced apart joint surfaces spaced apart to coincide with the joint surfaces of a respective lobes. The spaced-apart joint surfaces of the support member being profiled to mate with the corresponding joint surface of the lobes.