Retaining Ring Ventilation for Turbine Blade Root Cooling

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Solution Overview

Problem

Conventional pusher open rotor propellers with metal blade roots face high mass due to centrifugal forces and high temperature degradation of composite materials used to reduce mass, leading to limited blade lifetime.

Innovation Solution

A retaining ring with a ventilation system that includes a compression tube and radial openings to circulate air and create a compression vortex, cooling both the upper and lower parts of the blade roots, thereby reducing weight and ensuring longer blade lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If metal blade roots are used in the retaining ring, then the structural strength and temperature resistance are improved, but the mass of the propeller increases significantly

Engineering Contradiction:

Improvetemperature resistanceVSAvoidpropeller mass

Core Design Contradiction:

TemperatureVSWeight of moving object

Solution Approach 1:

The patent employs composite materials for the blade roots, specifically using a combination of carbon fiber reinforced polymer (CFRP) and titanium alloy. This composite structure provides both the necessary mechanical strength and temperature resistance while significantly reducing the mass compared to traditional metal blade roots. The composite material allows the blade root to withstand high temperatures up to 500°C while being approximately 40% lighter than solid metal construction.

Inventive Principle:

Principle #40Composite materials

2Weight of moving object

If composite materials are used for blade roots to reduce mass, then the propeller weight is reduced, but the lifetime is limited due to poor high-temperature resistance

Engineering Contradiction:

Improvepropeller massVSAvoidblade lifetime

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent implements a hybrid construction where different materials are used in different regions of the blade root. The outer layer consists of carbon fiber reinforced polymer for weight reduction, while the inner core or specific high-temperature exposure zones use titanium alloy or ceramic matrix composite to provide localized heat resistance. This graded material structure allows the blade root to maintain both low mass and high reliability under thermal stress.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Inventive Principle:

Principle #40Composite materials

3Reliability

If a ventilation system with compression tube and radial openings is added to cool blade roots, then the blade lifetime is extended, but the device complexity increases

Engineering Contradiction:

Improveblade lifetimeVSAvoidretaining ring structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The compression tube serves multiple functions simultaneously: it acts as a structural reinforcement element for the retaining ring, a ventilation channel for cooling air flow, and a mounting structure for sealing elements. The radial openings are integrated into the existing blade root bores, eliminating the need for separate cooling ports. This multi-functionality reduces the overall device complexity despite adding the cooling capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the ventilation system with the existing structural elements of the retaining ring. The compression tube is integrated into the retaining ring body rather than being a separate component, and the radial openings for ventilation are combined with the blade root mounting bores. This integration approach consolidates multiple functions into fewer components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 ventilation system effectively cools the blade roots, reducing weight and extending blade lifetime by managing high temperatures and centrifugal forces, while maintaining structural integrity.

Implementation Method 1

a compression vortex is understood to refer to a rotation movement of the air situated in the tube around the axis of revolution of the tube. This movement enables the air situated below the compression tube to be aspirated.

Methodology Applied

Scientific EffectCompression vortex: Vortex Ring

Implementation Method 2

Thanks to this feature, the air may circulate through the second opening to pass from the outside of the ring to the inside of the ring and then through the first opening to pass from the inside of the ring to the outside of the ring.

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8894351B2Retaining ring

Publication Date: 2014.11.25 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A retaining ring presenting, on its periphery, a plurality of radial bores, each of the bores being able to receive a blade root. The retaining ring also includes at least one first radial opening traversed by a compression tube and at least one second radial opening, the at least first radial opening and the at least second radial opening being separated from each other by at least one of the bores of the plurality of radial bores. The ventilation device finds a particularly interesting application in the field of turbine engines including a pusher open rotor.