© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Developments in Modern Aero-Engines to minimize the Impact of Bleed Air

Dr. Dieter Peitsch

Rolls-Royce Deutschland Ltd. & Co. KGDahlewitz, Germany

Contact: dieter.peitsch@rolls-royce.com

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Outline

Why is Customer Bleed Air an issue for theengine?

What can be done to minimize the impact onto the engine?

Engine PerformanceHardware Design (Compressor)Safety

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

AE2100 (6,000 shp)

Tay (14,000lb thrust)

BR715(18,500-22,000lb thrust)

RB211-535(43,000lb thrust)

RB211-524(60,000lb thrust)

Trent 700(72,000lb thrust)

Trent 800(95,000lb thrust)

BR710(14,750lb thrust)

V2500(25-33,000lb thrust)

Trent 900(80,000lb thrust)

Trent 500(56,000lb thrust)

Trent 600(65,000lb thrust)

Trent 8104(104,000lb thrust)

Rolls-Royce Civil engine range

AE3007 (7,000lb thrust)T800 (1,350 shp) FJ44 (2,000lb thrust)

RR DeutschlandModel 250 (600 shp)

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Bleed Air for Cabin Air Pressurization

Rolls-Royce Deutschland BR715 Core Engine

HPC

Bleed Air taken from High Pressure Compressor (HPC)

Low High

Two Offtakes to cover Pressure and Temperature Requirements of ECS over Operating Range

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Impact of Bleed Air on Engine PerformanceIncrease in Fuel Consumption

0

1

2

3 BypassRatio 9:1

Fuel Consumption Increase (%)

BypassRatio 5:1

BypassRatio 2:1

No Bypass

Bleed Air taken from engine (% of total circulating Air in Cabin)

40 100

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Impact of Bleed Air on Compressor DesignTwo Offtakes affect Compressor Design concerning:

Casing Stiffness / Tip Clearance / Load Path along Casing Compressor Stability

Low Pressure Stage High Pressure Stage

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Minimize Impact of Bleed Air - Compressor Offtake

Optimize Customer Bleed Offtakes in Compressors

Divorce Customer Bleed Offtake from any other Offtake, e.g. for Secondary Air System to avoid negative Impact onto Engine Safety in Case of Customer Bleed Pipe Rupture

Design Offtakes such, that Pressure Losses in the System are at a minimum level to achieve required Air Flows

Target: Move Offtake to the most upstream location possible to minimize negative effect on engine performance

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Optimization of Compressor Offtakes - ResearchInstitute for Jet Engines (ISA), University of the German Armed Forces, Munich`Simple` Wind Tunnel with Pre-Swirl Stator and flexible offtake configurations

Stator

Offtake

Distributor Channel

Offtake Slot

Stator

Offtake

Distributor Channel

Offtake Slot

Stator

Offtake

Distributor Channel

Offtake Slot

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Flow Visualization in Distributor Channel

Top Wall

Line of Attachment

Line of Detachment

Line of Attachment

Line of Detachment

BottomWall

ISA, Munich

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Derivation of Flow Model in Distributor Channel

Lines of Attachment

Lines of Detachment

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Mach Number Distribution in Offtake MaE

0.4780.4680.4570.4470.4370.4260.4160.4060.395

Direction of Swirl

Direction of Main Flow ISA, Munich

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Optimization of Compressor Offtakes - Research

Computational Fluid Dynamics to assess flow paths of air flowing from compressor annulus to customer bleedport

Multiple Configurations

Loss Assessment and Validation against Experiments

Y

Z

X

ISA, Munich

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Impact on Aircraft Safety AssessmentAny oil leaking from an engine, entering the aircraft customer bleed offtake, is classified as HAZARDOUS

Customer Bleed Offtake

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Minimize Impact of Bleed Air – Bearing Chamber

Ensure reliable Sealing of Bearing Chambers

Advanced Concepts and Technologies

Prediction Capabilities forAir and Oil System

Operation during transient Engine Manoeuvres

Replace Labyrinth Seals:Reduce sealing air req‘mentsReduce Number of PartsLess Design Complexity

Numerical Simulation:Reduce req`d safety marginsIncrease Accuracy for

Component Specification

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Bearing Chamber Sealing – Major Design ChangesOld Design (Labyrinths):Scavenge and Vent required

High Air Flow Requirements for Sealing

Deterioration of Seals

New Design (Carbons):Combined Scavenge-Vent

Less Complexity

Seal Deterioration at minimum Level

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Improve Transient Prediction Capabilities for Air and Oil System Performance

Simulation of Components using MATLAB/Simulink Software

Component Characteristics dependent on Engine Powersetting, e.g. Feed and ScavengePumps driven by Accessory GearboxMass Flows, Pressures and Temperatures

Prediction of Time-accurate behaviour crucial to predict and avoid Oil Leakage from the Bearing Chamber

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Result from Transient Calculation during acceleration and deceleration of the Engine

Time (s)

Delta Pressureacross air/oilseal

+

0

-

Acceleration Deceleration

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Avoid negative Pressure Difference by better Scavenge Pump

Delta Pressureacross air/oilseal

+

0

-

Increased Flow

Capacity of Pump

Time (s)

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Avoid Oil Leakage during Transients by Introduction of a new scavenge pump control conceptAir Mass Flow through carbon seal (kg/s)

Time (s)

© (Rolls-Royce Deutschland 2003)International Aviation Conference, October 2003, London

Finally, where is Aircraft Propulsion going to?

Thank You!