Overview
A principal contributor to affordable and sustainable public air transportation will be the introduction of more fuel-efficient propulsion systems, one of which is the Open Rotor Engine concept. Unlike turbofans, open rotors must vary blade pitch to accommodate power and aircraft speed range, so a key element to the viability of the concept is the actuation and control of the blade pitch via the Pitch Change Mechanism (PCM). GE Company Polska, Warsaw Institute of Aviation and GE Aviation Systems Ltd (trading as Dowty Propellers) proposed to build on the background of JT1-CS-2009-1-SAGE-02-001 as support for the SAGE 2 engine PCM.
The work packages proposed via this application focused on the design, manufacturing and testing of key components associated with the down selected PCM concepts from JT1-CS-2009-1-SAGE-02-001. The proposal contained detailed design, manufacturing and assembly of key components and test benches, design and procurement of required instrumentation, key components maturation test plans, description of the test support and test data post processing. The deliverables from the programme were the definition of the selected key components with 3D models, complete definition of test benches, evaluation of vendors and suppliers. All activities were summarised in comprehensive reports. The work packages are closely aligned to the key technology's maturation plans, in preparation for the ground demonstration of the open rotor engine.
Funding
Results
Executive Summary:
Environmental considerations defined by Clean Sky objectives such as reduced aviation carbon footprint, reduction of nitrogen emissions and noise, demand significant fuel burn reduction over current state of the art aviation propulsion systems. An Open Rotor propulsion system has higher propulsive efficiency than the current technology by virtue of its much higher By-Pass Ratio (BPR), a major contributor in achieving significant fuel burn savings. In order to maintain each propeller in a contra-rotating propeller at its correct and efficient operating point, its blade pitch must be controlled to absorb the supplied power and achieve the required rotational speed. The most effective systems in use today have independent hydraulically actuated pitch-change mechanisms (PCM) driven by a single turbo-propeller engine through a differential epicyclical gearbox. A Counter Rotating Open Rotor (CROR) in a Pusher configuration, such as the SAGE2, adds additional elements of technical difficulty i.e. blades that are situated at large diameters, severe thermal conditions and extreme loads. A novel pitch control mechanism is required for actuation and control of the blade pitch of an Open Rotor engine. Furthermore, robust and accurate PCM control system is crucial for exact control of the blade pitch and thus for frictionless operation of CROR engine. This project was aimed to address PCM technology maturation and development challenges required for reliable Pitch Change Mechanism operation in SAGE2 Counter Rotating Open Rotor engine.
Two main deliverables were foreseen as part of this program:
- A preliminary design of the forward and aft pitch change mechanisms for the SAGE2 Open Rotor
- A pitch change mechanism architecture with a Technology Readiness Level of 5
Both of these objectives were successfully met within this program. The first was through the delivery of both 3D models and successful completion of Preliminary Design Reviews for both FWD and AFT PCMs with the Topic Leader. The novel designs were able to meet all of the difficult integrational and functional requirements.
The second, and much more involved subject, was to ensure that the main PCM architecture was verified in a laboratory environment. In support of this point, a new test facility was developed to perform full scale system integration testing of a PCM. The testing was successfully carried out with the Topic Leader in the first quarter of 2016. The testing was broken down into two main areas; verification of PCM characteristics and endurance testing. Several key conclusions were made regarding the PCM as part of this testing:
- on the whole modelling of PCM characteristics was validated
- the PCM architecture did not undergo any unforeseen failure or wear as a result of the test campaign
- several novel solutions (lubrication and kinematics) worked successfully
The overall conclusion was that the PCM architecture that was tested as part of the OREAT II project could be used for the SAGE2 GTD testing.