A Novel Approach to Low Emission Combustion Rig Testing (2016)

Future engine programmes are facing significant challenges with demanding development schedules and ambitious technical performance requirements. In addition, a new Rolls-Royce generation of rich burn - quick quench - lean burn (RQL) low emission combustor is in development to reduce NOx emissions by more than 30% compared to current in-service technology of BR700 engines. These stringent emission targets require the introduction of latest combustor technologies with fast quenching jet air mixing accompanied by advanced cooling designs. To mature these new technologies they have to be validated on rig level before their implementation within an engine development programme. Hence a novel, accelerated approach for combustion rig testing has been developed. This utilised advanced preliminary and CFD tools for the definition of the combustor subsystem and fast-make innovative and manufacturing techniques for the make of the rig hardware, which had never been attempted before within Rolls-Royce for this type of application. The main purpose was to provide a process for fast manufacturing a full annular prototype combustor, which allows fast turn-around times of combustor hardware and testing of multiple configurations upfront any engine development programmes providing valuable, early test data. The advantage of the new approach is to enable early testing and hence down-selecting between different low emission combustor and component standards assessing key combustor attributes and risks. This represents a significant step towards a right-first-time combustor into future products. Full Annular (FANN) rig testing is a standard used to evaluate the aero-thermal performance of the combustor and to understand, amongst others, gaseous and particulate emissions, thermo-acoustic characteristics, combustor exit temperature traverse and combustor liner temperatures. FANN rig tests are frequently undertaken for new engine development programmes, but typically testing occurs late within the engine development programme due to extended lead times of conventional combustor manufacturing, causing significant risks to the programme not meeting customer or legislative requirements. Additive Layer Manufacturing (DLD) is an emerging technology of significant interest to Rolls-Royce and offers many opportunities for improving product competitiveness and lead-times. The Rolls-Royce Deutschland combustor team have been at the forefront of this technology advancement over recent years and therefore decided to fully exploit the lead-time reductions offered by both designing and manufacturing the rig combustor with DLD. Due to the limited physical size of the available machines, the combustor could not be fully 3D printed in one operation, so it was split into 8 sectors, which were printed individually and then laser welded using an automated operation. The total lead time for the combustor make was 3.5 months which corresponds to a 70% reduction compared to a conventionally made combustor with a typical lead time of 18 months. This was achieved through close cross-functional working with suppliers using a series of manufacturing trials for and welding and a design for DLD approach. The first fast make combustor - for whose a patent has been granted - together with a new rig was designed, manufactured, and delivered to test, based on the novel approach, according to schedule. Multiple low emission full annular combustor configurations have been tested delivering precious data to enable a substantiated combustor standard down select. Part of the work to be presented has been supported through the Lufo IV programme FetMaTec (20T0903A) and the Lufo V programme EmKoTec (20T1313) enabling more efficient combustion testing in the future.