NEWAC Overall Specification, Assessment and Concept ... · • Established preliminary design...

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.

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

NEWAC Overall Specification, Assessment and Concept Optimization

Andrew Rolt, Rolls-Royce plc.

with contributions from: Konstantinos Kyprianidis, Cranfield University; Stefan Donnerhack and Wolfgang Sturm, MTU;

Pascal Coat, Snecma; Salvatore Colantuoni, Avio;and Sebastian Bake, Rolls-Royce Deutschland.

© 2010 Rolls-Royce plc and NEWAC 1



Outline of presentation

• NEWAC engine concepts• SP1 organisation, partners and methods• Techno-economic and environmental risk assessment (TERA2020)• Study engines and technology assessments• Lean-burn technologies and NOx emissions• Conclusions




The four main NEWAC engine concepts assessed in SP1

Intercooled

Active coreIntercooled and recuperated

Flow controlled core




SP1 Whole Engine Integration – three work packages

Work Package 1.1- NEWAC study engines were specified and their performance and designs

have been assessed, on an ongoing basis, in comparison with reference engines, to identify costs and benefits of NEWAC technologies

Work Package 1.2- New combinations of NEWAC and other new technologies were proposed

and assessed to see if they could better the original engine conceptsWork Package 1.3

- The original NEWAC engines were modelled using TERA2020 softwaredeveloped in the NEWAC, VITAL and DREAM programmes

- TERA2020 extends the scope of the SP1 whole engine assessments and provides a tool for rapid initial evaluation of variant engine designs

- Also used for sensitivity studies and optimization studies

Short RangeLong Range

- 30,000 and 70,000 lbf thrust engine designs were assessed against requirements set by Airbus for two aircraft types




SP1 Whole Engine Integration – Partners in SP1

WP1.1

Specification & Assessment

Airbus

Rolls-Royce Deutschland

Techspace Aero

Turbomeca

AVIO

MTU Aero Engines

Rolls-Royce plc

Snecma

Volvo Aero

Cranfield University





WP1.1


Airbus


Techspace Aero

Turbomeca

WP1.2

Integration & Optimisation

AVIO

MTU Aero Engines

Rolls-Royce plc

Snecma

Volvo Aero






WP1.3

TERA2020

WP1.1


Airbus


Techspace Aero

Turbomeca

WP1.2

Integration & Optimisation

AVIO

MTU Aero Engines

Rolls-Royce plc

Snecma

Volvo Aero


Chalmers University of Technology

Technical University of Athens

University of Stuttgart




Methods

• Established preliminary design methods were used by MTU, Rolls-Royce and Snecma to set specifications and technology targets for the seven turbofan engine models in WP1.1 and then for three additional models in WP1.2

• Engine specification starts with the thrust requirements, a design concept and initial estimates of the performance available from major components and systems.

• The next step is to construct design and off-design performance models. Then major components are sized and the gas path annulus is defined.

• Iterative design studies and assessments are made to refine the performance model and to complete a preliminary mechanical layout for the engine.

• Finally nacelle lines are constructed and the overall powerplant weight, drag and unit cost can be assessed

• In WP1.3 the TERA2020 tool was used to model these engines and assess the economic and environmental impact of the new designs and technologies

• TERA2020 was also used to make sensitivity and optimization studies around the modelled engine configurations




Optimisation and design space exploration with TERA2020

• Block fuel benefits result mainly from improvements in:

1. The thermodynamic cycle (considering the engine weights and the aircraft mission).

2. Matching the engine to the aircraft (assessing the ‘snowball’ thrust reduction effects by using a ‘rubberized wing’ aircraft model).

Simplified representation of a design space explored with TERA2020

• Note there is not just one optimum design• The optimum depends on the objective function

and the applied constraints




Comparison of TERA2020 results for optimised engine/aircraft combinations with the corresponding initial (nominal) TERA2020 models

Engine Configuration

BlockFuel

DOC Noise Margin[EPNdB]

DDTF-IC-LR -2.8% -1% +1.3

CRTF-FCC-LR -3.2% -3.6% +1.7

GTF-AC-LR -3.2% -0.5% +3.5

IRA-GTF-LR -5.7% -2.0% +0.8

DDTF-IC-SR -7.4% -6.7% +3.5

CRTF-FCC-SR -6.4% -4.5% +3.5

GTF-AC-SR -5.7% -4.4% +6.0

This table shows the best engines for block fuel improvements achieved by TERA2020 optimization studies. Different design constraints come in to play as the various engine types are scaled.

Note the original (non-optimized engines) were designed for a set of thrust requirements that were completely reassessed in the TERA2020 study. Takeoff distance and time to height constraints were more easily met on the SR aircraft and this has resulted in greater reductions in thrust, block fuel and DOC for the NEWAC SR engines.

This table assumes that all component and systems technology targets set in NEWAC will be met, however TERA2020 sensitivity study results can be used to assess the impact of missing some of the technology targets.




Intercooled engines and SP3 technologies

Intercooler modules

Intercase design

HP ducting for intercooler

HP compressor tip injection and tip clearance control

Bypass duct offtake and LP ducting

HP compressor aerodynamics

LDI combustor(Direct drive fan)




Intercooled engine technology assessment

SP3 Technologies: Status:

Improved IPC exit and HPC entry ducts for intercooler, designed and tested

Performance targets met

LP bypass offtake duct experiments completed, including bled diffuser testing

Performance targets met

Improved intercooler matrix entry and exit geometry, flow distribution to reduce losses

Enabling technologies to reduce intercooler volume and x-section

Prototype intercooler modules designed, analyzed and manufactured (together with some limited testing)

Predicted losses exceed the original targets *

Whole Engine Mechanical Model (WEMM) studies to ensure the intercooled engine core has adequate stiffness to maintain tip clearances

HPC casing distortion now greatly reduced relative to original design *

Intercooled engine intercase: alternative aero designs thermo-mechanically analyzed

OK for stress, stiffness/weight issue still being addressed *

HPC rig test to improve efficiency and to demonstrate adequate surge margin

Surge margin OK, performance targets 90% met *

HPC tip blowing system demonstration Successful test

HPC passive clearance control experiments Tests ongoing

* Potential for 4% CO2 reduction is not yet demonstrated because these four technologies have not met alltheir performance or weight targets




IRA engine and technologies

Improved centrifugal compressor

Installation of recuperator modules optimized

Alternative compressor designs

LPP combustor

(Geared fan)




IRA engine SP2 technology status

Optimised radial HP compressor for improved efficiency at lower weight

No stability loss

New inlet hub/tip ratio

Radial/axial diffuser to suit ducting

Recuperator and hot nozzle geometry and arrangement to reduce hot flow losses

Minimise loss for fixed matrix geometry:

Modified exchanger and nozzle geometry

Adapted flow guidance

Resized heat exchanger

Design and integration




Active core engine and SP4 technologies

(Geared fan) Active tip clearance control system

PERM or LDI combustor

Active Cooling Air Cooling: heat exchangers, valves, new combustor case etc.

Active surge control




Active core engine technology assessmentSP4 Technology Targets: Status:

Active Cooling Air Cooling Basic test of heat pick-up

Cycle benefit from 35% reduced cooling air mass flow

Partly achieved *

+1% improved turbine efficiency Partly achieved *

Smart HPC technologies:+1.5% improved compressor efficiency+15% surge margin

Demonstration on two different rigs

Active surge control with air injection Validated by rig test

Active clearance control - thermal System studies only

Active clearance control - mechanical adequate surge margin

Demonstrated on static rig test

Combined benefits -4% SFC-1% weight

Largely achieved, but over-weight

* Potential for 4% CO2 reduction has not been fully demonstrated(the technologies do not consistently benefit all phases of flight)




Flow controlled core SP5 technologies

(Counter-rotating fan and LP turbine)

PERM or LDI combustor

Improved rotor path lining

Aspirated blading

Tip flow control

Advanced HP compressor design

Active stall control © 2010 Rolls-Royce plc and NEWAC 17



Flow controlled core technology assessment

SP5 Technology Targets Status HPC high-speed rig test with tip flow control

Significant efficiency gain demonstrated

Aspiration on blade profiles to enable blade count reduction

Assessment shows a modest efficiency benefit

Active stall control by fast acting valves Significant improvement in surge margin but with some weight penalty

Stall control by tip flow recirculation (advanced casing treatment concepts)

Second round assessment shows a useful improvement in surge margin, with less weight penalty than the fast acting valve system

Rub management The model of the abradable and wear is being correlated

Development of an improved abradable material

Rub test comparisons with a baseline material are completed




NEWAC lean combustion technologies4 core concepts 3 Injection Systems Concepts Scientific approach

SP2 (IRA)

SP3 (IC)

SP4 (AC)

LP(P)

LDI

PERM

SP5 (FCC)

Injection System Single sector rigs• Sub-atmospheric sector• Low power sector• Medium power sector• High power single sector

Combustor Full annular testing• Sub-atmospheric and atmospheric

light-around• Low power efficiency and emissions• High power performance (thermo-

acoustic behaviour, circumferential instability

TRL 3-4

TRL 5-6

LDI – Lean Direct Injection

PERM – Partial Evaporation & Rapid Mixing

LPP – Lean Premixing Pre-vaporizing




NEWAC Cycles: Interim NOx Emission Prediction based on 1st FANN (LDI) and 1st injection system tubular combustor test results (PERM and LPP)

0102030405060708090

100

10 20 30 40 50 60 70 80

OPR - Overall Pressure Ratio at Takeoff

DPN

Ox/

Foo,

g/k

N

NOx CAEP2 limit

LDI (30% CAEP2)

PERM (35% CAEP2)

LPP (40% CAEP2)

IC - LR , LDI

IC - SR, LDI

FCC - LR, LDI

AC - LR, LDI

AC - SR, PERM

FCC - SR, PERM

IRA - LR, LPP




SP1 Conclusions: overall fuel-burn assessment

Engine Concept Status re. Fuel Burn at Fixed Thrusts High OPR Intercooled engine

NEWAC -4% target is not met yet because of weight and drag penalties. A lighter and more compact intercooler installation is needed. Some SP3 technology can apply to other engines types

Intercooled and Recuperated engine

NEWAC target for -2% fuel burn relative to the CLEAN engine is achieved

Active Core engine NEWAC -4% targets nearly achieved, with the ACAC technology giving the biggest benefit

Flow controlled Core engine

NEWAC -3% fuel burn targets forecast to be met for LR engine and nearly met for SR engine

NEWAC WP1.2 Study engines

The best combinations of technologies will come close to meeting the NEWAC -6% CO2 target


NEWAC Overall Specification, Assessment and Concept ... · • Established preliminary design...

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