CMC Turbine Nozzle Blade Mast Ventilation Routing

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Solution Overview

Problem

Ceramic matrix composite (CMC) materials used in turbomachine nozzle blades are sensitive to mechanical stresses and differential thermal dilations, leading to positioning issues and sealing defects due to their higher stiffness and smaller dilation compared to metallic materials, especially in high-pressure portions of turbomachines.

Innovation Solution

A turbomachine turbine nozzle design featuring CMC blades with a hollow structure and a tubular mast that routes ventilation air, where the mast is structurally connected to metallic shrouds rather than the CMC blades, using an engagement portion and notch for precise positioning and limiting relative movement, thereby controlling temperature and pressure effects independently of the CMC blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If CMC materials are used for turbine nozzle blades to withstand high temperatures, then the maximum temperature tolerance is improved, but the positioning accuracy deteriorates due to differential thermal dilation with metallic parts

Engineering Contradiction:

Improvemaximum temperature toleranceVSAvoidpositioning accuracy

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The nozzle assembly is segmented into distinct CMC blade components and metallic support structure components, allowing each material to be optimized for its thermal properties while maintaining overall assembly integrity through modular construction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design accommodates parameter changes in blade positioning by allowing controlled movement through the cavity structure, where blades can thermally expand and contract independently within defined geometric constraints rather than maintaining rigid fixed positions

Inventive Principle:

Principle #35Parameter changes

2Weight of moving object

If CMC materials are used for turbine nozzle blades, then the density is reduced, but the mechanical strength deteriorates due to greater sensitivity to mechanical stresses

Engineering Contradiction:

ImprovedensityVSAvoidmechanical strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The nozzle assembly employs a composite material system where CMC blades provide lightweight high-temperature capability while metallic support structures provide mechanical strength, creating a hybrid construction that leverages the advantages of both material types

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The metallic support structure acts as an intermediary that bears the mechanical loads and stresses, allowing the CMC blades to function primarily for aerodynamic purposes at high temperatures without being directly responsible for withstanding all mechanical stresses

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If CMC blades are used in high-pressure portions of turbomachines, then the performance is improved, but the sealing deteriorates due to differential dilation causing clearances between parts

Engineering Contradiction:

ImproveperformanceVSAvoidsealing

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The design employs a cavity structure that can accommodate dimensional changes in the CMC blades during thermal cycling, maintaining sealing through geometric flexibility rather than rigid fixed clearances, where the blade positioning is defined by the cavity geometry rather than tight tolerances

Inventive Principle:

Principle #30Flexible shells and thin films

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

This design improves sealing and maintains accurate positioning of the nozzle blades, reducing differential dilations and leaks while allowing the CMC blades to deform independently, thus enhancing the performance and reliability of turbomachines operating at high temperatures.

Implementation Method 1

The relatively cool extracted upstream of the combustion chamber is injected inside the mast to cool the blade, from the inside, by impact

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

the cooling air creating a protective film of cooler air flowing along the outer surface of the blade

Methodology Applied

Scientific EffectThermal film protection: Boundary Layer

Implementation Method 3

CMC materials have advantageous thermo-structural properties, i.e. the mechanical properties make them able to constitute structure elements and the capacity to retain these properties at high temperatures

Methodology Applied

Scientific EffectThermal stress resistance: Thermal Expansion

Data Source

PatentUS11965433B2CMC guide vane for a turbomachine turbine

Publication Date: 2024.04.23 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A turbomachine turbine nozzle extending around a central axis, including at least one radially outer shroud, at least one radially inner shroud, and at least one blade made of ceramic matrix composite material, distinct from the radially inner shroud and from the radially outer shroud, and extending radially between the radially inner shroud and the radially outer shroud, the blade being hollow and including a cavity opening at a radially inner end and at a radially outer end of the blade, the nozzle including at least one tubular mast arranged in the cavity of the blade and allowing routing the ventilation air passing through the cavity of the blade, the mast including a radially outer end attached to the radially outer shroud, and a radially inner end cooperating with a radial flange for positioning the radially inner shroud.