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Contra-Rotating Open Rotor (CROR) Propeller barrels

Final Report Summary - GREENBARRELS (Contra-Rotating Open Rotor (CROR) Propeller barrels)

Executive Summary:
The aircraft manufacturers need to find higher engine efficiency with much lower fuel consumptions. For this target, several developments have been launched by engine manufacturers.

One of the most amazing engines from the architecture point of view is the so called the Contra Rotating Open Rotor.

This engine is to be proven to save 30% fuel consumption over successful engines such as CFM56.

To prove this the SAGE 2 in CLEANSKY is the Integrated Technology Demostrator initiative in which a full engine will be developed to carry out a Ground test managed by the CS engine leader’s companies.

A Consortium of two organisations from Spain, was formed to develop from the conceptual design up to the delivery of rotating barrels to the SAGE 2 Open Rotor Demo Engine.

These components are in the contra rotating area on a highly vibrational contra rotating environment and high thermally stressed as well.

The weight constraint is a capital requirement to meet the full weight goal of the engine.

These constraints and the multitude of interfaces has made the GREENBARRELS project of a high complexity R&T.

The Greenbarrels project, led by EURECAT (former ASCAMM) and with partner Industrias Puigjaner (Denn), has to consider the following main components functions, for transition and aero ducts (technical name for the barrels in the Open Rotor engine):

Transition ducts:

• To channel the flow of main hot gases stream to the exhaust

• To channel the secondary airstream (together with rotating cowls)

Aero ducts:

• To channel cooling air for the lubrication oil

During the project is has been addressed different work steps with the aim to achieve the final target. The steps can be summarized as:

• Analysis of requirements
• Selection of architecture for the barrels
• Material and process detailed selection
• Risk analysis continuous monitoring
• Selection and analysis of concept for the Concept Review (CoR)
• Performing all preliminary design phase
• Carrying out manufacturing trials
• Passing the Preliminary Design Review (PDR)
• Carry out Critical Design Phase
• Pass CDR
• Perform manufacturing, control and delivery of all barrels’ part to SAGE 2 OPEN ROTOR Demo Engine.
• To research about manufacturing techniques that allows minimal chip removal

With this approach the project has fully achieved the marked objectives and today all components are assembled in the demo engine.

Project Context and Objectives:
Project Context
ACARE (the Advisory Council for Aviation Research and Innovation in Europe) has set guidelines for the environmental impact of aerospace that target significant reductions in aircraft emissions.

The ACARE targets for civil aircraft include NOx and CO2 emissions reductions of 80% and 50% respectively by 2020.

Although airframes make a significant contribution, most of the balance will be contributed by the engines.

These contributions are expected to be achieved by higher bypass ratio engines which will allow to increase the fuel saving by 30%, and so the CO2 generation will be reduced by the same amount.

The Open Rotor engine is the architecture that will allow a high increase in the bypass ratio compared with any current engine or in development. While ratios of 14:1 can be achieved with some technologies in development.

The bypass ratio of an Open Rotor can be in the range of 50:1.

These configuration needs maturation in terms of: the architecture for the full engine, the development of specific components, only available in this engine, by development means design strategies and optimization, as well as manufacturing processes adapted to challenging components.

The project work of GREENBARRELS project was centred on the specific requirements of the SAGE 2 initiative; however, the results will have much wider applicability. The objective of SAGE 2 is to demonstrate a full operative Open Rotor engine for a Ground Test Bench to allow maturation to TRL5-6.

It is expected that a full test bench campaign will be carried out in SAGE2 on a specific test bench for an Open Rotor.

Test results on ground bench will pave the way for a future flight test to demonstrate the fuel saving and other concerns in real flight conditions.

Project Objectives
GREENBARRELS has addressed the challenge of developing all components for the transition and aero ducts, components that are in the counterrotating area. The aim was to find the right design to sustain the functional and failure loads, while keeping it main function of channel the main air flow from the combustion, as well as the secondary air flow for ventilation. The development included the analysis of load cases, dynamic analysis, fatigue analysis, assembly analysis, manufacturing analysis and the analysis of the right quality plan for the parts.

Based in the analysis of thought requirements, the specific objectives of the Greenbarrels project were:

a. Selection of architecture for the barrels, the selection was based in the analysis of pros and cons of several proposed barrels architecture

b. Material and process detailed selection to allow to manufacture the barrels to sustain load, temperature and other constraints

c. Risk analysis continuous monitoring to allow early detection of risk an ow to mitigate it considering the high importance of the integrated Demostrator to achieve.

d. Selection and analysis of concept for the Concept Review (CoR). Based on most promising architecture for barrels part, a pondered evaluation was carried out to be presented in the CoR meeting.

e. Performing all preliminary design phase. The results of the CoR, was a selection of architecture to follow in the preliminary design phase to probe toe suitability of this architecture for the function assigned to the barrels components
f. Carrying out manufacturing trials. With the selected manufacturing processes and materials, it was necessary, according with risk analysis, taking into account the requirements, to carry out manufacturing of dummy components in sizes similar to he expected for the barrels, as well as with parts details.

g. Passing the Preliminary Design Review (PDR). The preliminary design stage with one architecture, selected, as well as with manufacturing trials performed, allowed to meet on time the next milestone which was the PDR.

h. Carry out Critical Design Phase. With results of PDR the last stage of design started to have a detailed set of barrels components for manufacturing,

i. Pass CDR. At the end of the CDP, the next milestone was the CDR where all designed details were studied to allow start the manufacturing phase

j. Perform manufacturing, control and delivery of all barrels’ part to SAGE 2 OPEN ROTOR Demo Engine.

k. To additionally research about manufacturing techniques that allows minimal chip removal for parts such as barrels shapes.

Project Results:
Project Results:
o In collaboration with a leader in the aero engine industry, the Consortium could produce a list of components optimized for requirements and environmental specifications for operation in an integrated engine. Some of the specifications met are:

• Functional
• Dynamical performance vs excitation frequencies.
• Sealing performance of the counterrotating area
• Temperature range of operation
• Structural performance vs load cases, both static and fatigue
• Interface achievement

o Research and development of materials and designs for barrels components, through material selection, manufacturing trials and characterization.

o The barrels components were subjected to empirical evaluation through a series of manufacturing tests to ensure the quality of the material, process and manufacturing stages.

o The outcome of the initial test was the derisking of the manufacturing of components to deliver to SAGE2 Demo Engine.

o The materials and designs were optimised through modelling and presented in the form of Design reports during CoR, PDR and CDR meetings.

o The validated barrels design was manufactured and delivered to SAGE2.

o Delivered components mostly complied with the built compliance matrix.

o Design and manufacturing of a demo part in non-chip removal technologies was also Achieved

o The immediate exploitation of the knowledge developed is to have allowed Eurecat to position in additional private contract projects for other engines.

o The future exploitation of barrels will follow the path set by the leaders for the Open Rotor

Potential Impact:
Potential Impact:
The barrels development seen in an integrated environment into SAGE2 has the potential to contribute in a highly significant way to attain the following impacts:

o CO2 emission reduction by 30%
o Fuel consumption reduction by 30%
o NOx reduction

The GREENBARRELS project has been widely disseminated through the attendance to the following exhibitions:

• AMD Sevilla 2012
• AMD Torino 2013
• AIRTEC Frankfurt 2012
• AIRTEC Frankfurt 2013
• AIRTEC Frankfurt 2014
• AIRTEC Munich 2015
• AIRTEC Munich 2016

In regards to exploitation of results, thanks to the experience acquired during GREENBARRELS project EURECAT, currently the centre is getting private contracts for developments of new components in other engine architectures.

List of Websites:
The Main information of the Project is handled trhoguh EURCAT's webpage:
The Main contact is: Mr. Angel Lagraña
E-mail address:
Contact Phone: +34935944700/+34648725077