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European Workshop on New Aero Engine ConceptsMunich, 30 June – 1 July 2010

Intercooled Engine and Integration

NEWAC is an Integrated Project Co-funded by the European Commission within the Sixth Framework Programme(2002-2006) under Thematic Priority 4 Aeronautics and Space.

Nick Baker, Rolls-Royce plc

© 2010 Rolls-Royce plc and NEWAC


Intercooled Core – Introduction

intercoolerbypass ductLow pressure ducting

intercase

Intercooling between the IP and HP compressors allows the engine cycle to bere-optimised with a higher overall pressure ratio (OPR) than conventional engine architectures


2© 2010 Rolls-Royce plc and NEWAC

This yields significantly reduced fuel consumption and can also lead to cuts in NOx emissions. The NEWAC objective is to achieve a 4% reduction in SFC

HP compressor

IP compressor

HP compressor

IP compressor

High pressure ducting


Intercooled Core – Technical Approach


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Intercooler and integration

� Compact, lightweight and high performance intercooler design

� Whole engine integration and intercase design

� Design and validation of low pressure loss ducts

Improved HPC (higher overall pressure ratio)

� Advanced highly efficient reduced core size compressor

� Stability enhancement for intercooled core operability

� Improved tip clearance design


Intercooled Core – Partners

WP3.1 Coordination & Specification

Volvo Aero


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Rolls-Royce Deutschland

Rolls-Royce plc




Volvo Aero



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WP3.2 Whole Engine Integration of Intercooled Concept

Loughborough

Rolls-Royce plc



WP3.3 Intercooler Aerothermal Systems


Volvo Aero



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Loughborough

Systems

Oxford

Scitek Consultants

Rolls-Royce plc



WP3.3 Intercooler Aerothermal Systems Sussex


Volvo Aero



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Loughborough

Systems

Oxford

Scitek Consultants

Sussex

DLR

WP3.4 Improved Blading & Gas Path Design

Rolls-Royce plc





Volvo Aero



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Loughborough

Systems

Oxford

Scitek Consultants

Sussex

DLR

Cambridge

WP3.5 Stability Enhancement for Core


Rolls-Royce plc





Volvo Aero

WP3.6/3.7 Technology Validation Rig Manufacture &Test



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Loughborough

Systems

Oxford

Scitek Consultants

Sussex

DLR

Cambridge

WP3.5 Stability Enhancement for Core


Rolls-Royce plc



Intercooled Core – High pressure ducting The intercooled aero-engine concept features two new high pressure ducts:

- A ‘S’-duct which transports IP compressor delivery air to the intercooler modules.- A ‘C’-duct which carries the cooled air to the HP compressor.

‘S’-duct

Heat exchanger


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Research at Loughborough University has focussed on 3D duct design and CFD optimisation to minimise losses

Complete high pressure duct rig


‘C’-ductHeat exchanger module

2/3 scale tests with detailed pressure traverse measurements have demonstrated that the HP duct system has met or exceeded pressure loss targets

(For details see ‘Intercooler High pressure Ducting System’ presented by Duncan Walker)


Intercooled Core – Low pressure ducting A new low pressure duct is required to transport cooling air from behind the fan Outlet Guide Vane to the heat exchangers.

LP duct


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Low pressure duct rig

Loughborough University have carried out the design and performance assessment of this duct.Design considerations include:

- Fan OGV wake ingestion- Prediffusion and controlled diffusion- Downstream blockage- Boundary layer bleed

Results have built detailed understanding of system design parameters and shown diffusion and loss targets to be achievable


(For details see ‘Intercooler Low pressure Ducting System’ presented by Jon Carrotte)


To maintain compactness, both the hot and cold flows are turned through large angles upon entering and leaving the heat exchangers:

- potential to cause flow maldistribution - hence increase pressure loss and reduce effectiveness

Oxford University and Rolls-Royce have undertaken research to understand these effects through experimental and computational studies

Intercooled Core – Heat exchanger entry and exit los ses


Design guidelines for reducing aerodynamic loss and optimising effectiveness have now been established

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Cross-corrugated surface

Exit traverse probe

Aerodynamic probe at matrix exit


Through-

flow

Heat Transfer Measurement

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Side Wall

Main surface

(For details see ’Cross Corrugated Intercooler Installation’ presented by Pokwan Kwan)


For intercooling to be a viable proposition, a significant improvement in the compactness of air-to-air heat exchangers was required.

Rolls-Royce have developed an ultra-compact cross-corrugated heat exchanger concept

Intercooled Core – Compact heat exchangers


concept

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Manufacturing trial by selective laser melting in titanium.

IPC delivery air

Cooled IPC delivery air

Intercooler mini-module design

Bypass air


Manufacturing trials via selective laser melting have been carried out and a first prototype built

Further manufacturing process optimization is underway prior to pressure loss and effectiveness measurements


Intercooled Core – Whole engine mechanical modelling Intercooling causes a reduction in engine core size, which means that casings must be carefully optimised to maintain stiffnes. A Whole Engine Mechanical Model has been created by Rolls-Royce to:

- assess overall engine deformation under flight loads. - quantify casing distortions.

Initial modelling has shown that engine carcass flexibility needs to be addressed


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Complete powerplant WEMM

carcass flexibility needs to be addressed through redesign of engine structural components.

Further studies have demonstrated:- transmissions design, including main engine shafts and power offtakes. - bearing load management.

3D cutaway view



Intercooled Core – Intermediate casing design - The intercase is a major structural engine component which has a dominant impact on the engine’s structural integrity.

-Volvo has been focussed on a novel design of intercase suitable for an intercooled engine:

- Structural performance


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- Structural performance- Aerodynamic design of integral intercooler ducting- Manufacturability studies

- A baseline intercase has been defined and analysed. This met the majority of deign parameters but whole engine modelling highlighted additional stiffness to be required

-An alternative design with a novel gas path routing has shown potential for improved stiffness without aerodynamic loss, although weight is still challenging

Baseline intercase structure


Alternative intercase structure(For details see ‘Design of an intercase for an intercooled engine’ presented by Dennios Jacobsson)


Intercooled Core – Advanced High Efficiency Compress or The compressor design for an intercooled engine is demanding because:

- Altered IP/HP work split and compressor working lines- Off-design handling capability is more difficult.- The small core size puts pressure on maintaining competitive tip clearances and efficiency

Aero teams at Rolls-Royce UK and Germany have used the latest 2D/3D parallel CFD methods to optimise efficiency and


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latest 2D/3D parallel CFD methods to optimise efficiency and operability.

- Optimised leading edge shapes.- Optimised camber distributions.- Desensitize compressor performance to tip clearance.

Advanced compressor blading© 2010 Rolls-Royce plc and NEWAC

Detailed 3D design iteration

Design was validated via high speed rig test with both efficiency and operability targets met

(For details see ‘Design and Test of an Advanced HP Compressor’ presented by Mark Walker)


Methods for enhancing the stability of compressors have been investigated

Intercooled Core – Stability enhancement

CFD of stability enhancement via tip blowing using recirculating air

Multi stage self-recirculating tip blowing system was designed by Rolls-Royce Deutschland and demonstrated in the high speed rig test. Significant additional part speed stability was demonstrated but at a cost to high speed efficiency


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Mini-recirculating tip blowing system


a cost to high speed efficiency

An alternative locally recirculating stability enhancement concept was developed and tested on low speed rigs by the University of Cambridge. This has shown potential for a self regulating system that is only active at off design conditions without a high speed penalty

Multi stage tip blowing system

Casing Injection Extraction

Loop

Rotor Blade

(For details see ‘Tip Blowing for Stability Enhancement’ presented by Henner Schrapp and ‘Design of Alternative Stability Enhancement System’ presented by Stepanie Weichert)


The reduced core size of an intercooled engine poses a significant challenge to maintaining tight tip clearances

Intercooled Core – Passive Tip Clearance Control

CFD of stability enhancement via tip blowing using recirculating air

Research at Sussex University has been devoted to exploring passive control of tip clearance through thermomechanical design

One promising concept is that of inter-disc radial inflow

Radial inflow


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Multi Cavity Heat Transfer rig© 2010 Rolls-Royce plc and NEWAC

One promising concept is that of inter-disc radial inflow-replaces typical bouyancy driven flow in cavity-substantially higher heat transfer in the drum-improved transient thermal matching between drum and casing leads to improved tip clearance

Validation testing has recently been carried out on a multi stage disc heat transfer rig

Radial inflow to disc cavity

(For details see ‘Passive Tip Clearance Control’ presented by Nick Atkins)

Bore flow


Intercooled Core – Conclusion

- Intercooling offers the potential for advantages in terms of SFC and emissions reductions- Systematic investigation and validation of the key enabling technologies has been carried out by a strong team of industry and academic partners- Tests completed have shown that many of the performance targets can be met-There remain challenges to achieving the NEWAC sfc targets via intercooling


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-There remain challenges to achieving the NEWAC sfc targets via intercooling alone:

-Further progress is required in intercooler compactness and whole engine stiffness without compromising weight and nacelle drag


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