Lean Burn Technology at Rolls-Royce

Transcription

1 Lean Burn Technology at Rolls-Royce June 2014 FORUM AE Technology Workshop Kenneth Young Chief of R&T Combustion Sub-System 2014 Rolls-Royce plc The information in this document is the property of Rolls-Royce plc and may not be copied or communicated to a third party, or used for any purpose other than that for which it is supplied without the express written consent of Rolls-Royce plc. This information is given in good faith based upon the latest information available to Rolls-Royce plc, no warranty or representation is given concerning such information, which must not be taken as establishing any contractual or other commitment binding upon Rolls-Royce plc or any of its subsidiary or associated companies. Export control statement: This information is controlled by the UK Dual-Use List (rating PL9009.c) Trusted to deliver excellence

2 Rolls Royce Lean Burn Technology As with the rest of industry, certification values of NOx are reducing continuously. Rich Burn (phase 5 technology) is a robust, proven technology but is fundamentally limited in the level of NOx and smoke achievable. Lean premixing of fuel and air is needed for a step change in high power NOx and smoke performance. Fuel staging is used for operability: Rich pilot for low power stability Lean main zone for minimised NOx and smoke For an optimised solution, lean-burn is developed as a system within other engine systems: Control system Control laws Turbines Heat management system Installation

3 Combustor Technology Implementation Options Corporate and Regional Short Term MediumTerm Long Term Phase 5 Rich Burn Phase 5 Rich Burn with incremental improvements Lean Burn, Staged combustion Current rich burn combustor technology can deliver NOx in the range of 55-70% CAEP6 Combustion design influenced more strongly by complexity & weight than emissions. Middle of the Market Phase 5 Rich Burn Engine cycle Phase 5 Rich Burn with incremental improvements Lean Burn, staged combustion Large Engine Current rich burn combustor technology can deliver NOx in the range of 55-65% CAEP6 Combustion choice influenced by complexity, weight and emissions requirements. Future engine architecture will play a large role. Phase 5 Rich Burn Lean Burn, Staged Combustion Lean Burn with incremental improvements Current combustor technology can deliver NOx in the range of 60-80% CAEP6 Combustion architecture choice dominated by emissions requirements

4 RR Lean Burn Development A long term partnership UK Government 4 ATAP10 EFE Samulet SILOET 1 & 2 European Commission EEFAE (ANTLE, POA) FW7: Tecc, First, Impact, Lopocotep, Intellect, Lemcotep Clean Skies, SAGE 6 (ALECSYS) German Government Luftfahrtforschungsprogramme Lufo IV, V AG Turbo 2020

5 Rolls Royce Lean Burn Combustion System Architecture Movement tolerant FSN design Conventional ignition system Mounting in line with large engine practice Image Removed from Public Disclosure Optimised combustor volume High efficiency dump diffuser Compact nested pilot staged lean burn fuel injector 3rd generation cooling technology for ultra efficient cooling

6 Rolls Royce Lean Burn Fuel Spray Nozzle Tip Architecture Novel heat management of mains fuel by pilot fuel flow Technology scalable, proven on E3E and EFE test vehicles Smooth operation, enhanced mixing comparable with longer premixed ducts. Arrangement flashback and auto-ignition free Currently uses state of the art conventional manufacture. Design is Additive manufacture capable. Image Removed from Public Disclosure Staged fuelling with two flow circuits (pilot and main) Both pilot and main based on well established airblast technologies Fuel delivery system is heatshielded for improved thermal management Servicability is a key design feature

7 Airblast Atomiser Technology Focus Droplet Sauter Mean diameter Typical altitude windmilling range Both pilot and mains utilise airblast atomisation of a thin annular film of fuel by co-linear airstreams Used in entire RR aerospace product range Maintenance of a high relative velocity between liquid film and atomising airstream key performance parameter Airblast atomisation performance not greatly affected by injector flow number Atomisation dominated by air stream - insensitivity arises due to high atomising air velocities utilised by airblast atomiser No change across engine operating range in relative positions between fuel and air streams No reliance on discrete jet cross flow atomisation/jet trajectory/mixing mechanism Low sensitivity to fuel / air momentum ratio Flow number insensitivity facilitates 2 fuel circuit design and robust scaling. Rolls-Royce injector operation range (Rig and Engine) FN = Flow number (a measure of fuel flow rate for given fuel pressure drop) Air Liquid Ratio

8 Airblast Atomiser Technology Focus Pilot stream - no air Mains stream no air Pilot stream with air Mains stream with air Substantial development has been conducted on the detailed tip and atomiser technology Primary focus has been on: Ignition performance Aerodynamic stability High power mixing Impact on combustion performance and operability. Thermo-acoustics Development of fuel galleries for optimised thermal management performance and fuel draining. Design for production manufacture. Single Injector Test in a 20bar optical rig in lean burn mode at DLR Koln

9 Design Considerations for Aero Combustion Systems Operability Life Safety and Reliability Power Modulation Low NOx Pressure loss Combustion efficiency Weight System Integration and Interaction

10 System Level Issues Combustor Stability in Inclement Weather Water / Hail Ingestion Engines must be fully responsive to sudden changes in water content in transient manoeuvres Testing involves steady state, transient manoeuvres (slam decels) and sudden changes in water This is one of the most severe tests of the combustion system. ANTLE POA test Configuration Water fed directly into core engine Water loading scaled to match Trent 500 cert test Trent 500 bleed schedule overwritten (HP compressor bleed forced closed)

11 12:38:53 12:39:02 12:39:12 12:39:21 12:39:31 12:39:40 12:39:50 12:39:59 12:40:09 12:40:18 12:40:28 12:40:37 12:40:47 12:40:56 12:41:06 12:41:15 12:41:25 12:41:34 12:41:44 12:41:53 12:42:03 12:42:12 12:42:22 12:42:31 12:42:41 N3 % Transient Response to Water / Hail Ingestion TGT Speed T Engine idling before W sudden AT increase in water ER W Accompanying GPdip in TGT H triggers recovery logic 80 K Engine recovers and is maneuvered Water is removed and engine TG returns to normal T operation FL O T3 0 K 30 Water P3 0 psi Time PI LO T fue l flo w

12 Altitude (ft) System Level Issues Altitude restart Engines must demonstrate restart capability across a range of forward speeds and altitudes. Testing is conducted in an altitude cell to get the correct boundary conditions of pressure and inlet temperature Quick relight Certification requirement to immediately relight the engine in - flight while spooling down after a flame out. This can be caused e.g. by pilot error or compressor surge Starter assist starting 20s - 30s from idle Quick Relight 1s - 5s in climb Wind - milling starting Indicated Airspeed (knots) Wind - milling starting Certification requirement to restart the engine in - flight within a set time after a commanded or un - commanded in - flight shut - down Starter assist starting Certification requirement to restart the engine in - flight with starter assistance within a set time after a commanded or un - commanded in - flight shut - down 25 Two series of core tests have been undertaken in the E3E programme. Tests differed in configuration of fuel spray nozzle and controls architecture. Conditions across the full envelope were successfully achieved.

13 Altidude [ft] Results from the E3E Core Test Programme Core 3/2b test limit Full windmill relight loops achieved across the required forward speed envelope beyond 30,000ft altitude Test results exceeded certification and customer requirements Successful start within 90sec Successful start, time-to-idle > 90sec No ignition or pull-away VCAS (kts) Windmill ignition envelope of E3E Quick windmill relight loops also demonstrated without adverse affect on turbo-machinery Cold day starting achieved down to below -40C.

14 System Level Issues Emissions nvpm measured in mains operation lean burning mode Emissions are strongly affected by inlet pressure and temperature. The EFE high temperature demonstrator is designed to operate at extreme conditions allowing emissions to be fully validated across the full range of future engine cycles. Testing shows NOx levels in the region of 35 to 45% CAEP6 (dependent on cycle) 30-35% reduction to rich burn. In lean burn mode, the smoke emissions are virtually zero and in some cases, measured values are lower than ambient.

15 Next Steps All sub system and component technologies are now at a high level of readiness. Given the number of systems affected, there are many opportunities for undesirable emergent behaviour. As part of the CleanSky SAGE6 programme, RR are preparing for full system integration and validation on 2 retrofitted Trent 1000 engines: Icing testing Manitoba External noise testing NASA Stennis Flight testing company 747 flying test bed 15