Final Report Summary - CASE (Fuel Control System Sensors and Effectors)
Executive Summary:
Aero Engine Controls (AEC) identified several new technologies that offer the potential to provide the benefits to next generation fuel systems sensors and effectors.
This programme planned to develop these technologies independently of each other with Partners within the Consortium, specifically;
Acoustic Sensor (AEC)
AEC worked with both Morgan and Newcastle to carry out analysis and testing to confirm the proof of concept of the units both in the laboratory and on an AEC test rig (referred to as the first generation sensor). Testing of the first generation sensor design identified issues with the method of mechanical attachment of the active sensor element (the piezo-ceramic), as such a second generation sensor was designed by AEC, with the need to optimise the sensor packaging to make the sensor more compact and able to be fitted in a variety of different engine control applications. Unfortunately, testing proved that the second generation sensor was still not successful and as such further test programmes were put on hold and would be evaluated at a later date.
Piezoelectric Sensor (AEC)
A significant part of this activity was sub-contracted to the University of Bath. Five concepts were developed and the parties agreed that the Noliac ringbender was the suitable option. Laboratory demonstrator tests were completed and further investigation was required to look at suitable clamping options.
During 2014 the prototype still had several issues that needed fixing and the temperature testing was planned but not completed by June 2014.
Mass Flow Sensor (Oxford RF)
Oxford RF Sensors were selected to develop a fuel mass flow measurement system using high frequency ultrasonic techniques. Initial tests at Oxford RF showed that the sensor had potential for further development; however, after further testing of the mass flow measurement technology, it was considered that the project required substantial further development before it was appropriate to progress and as such the project was put on hold.
Eddy Current Sensor (Micro Epsilon)
The Eddy Current sensor was proposed as a replacement for Linear Variable Differential Transformers (“LVDTs”) used in current Fuel Metering Units. Eddy current sensors can offer significant size, weight, measurement accuracy, speed and reliability benefits compared to current LVDT technology. Micro Epsilon delivered 2 off sensors to AEC for testing. The intent was to complete the environmental test as a block test but it was decided that this was not be worthwhile above the components test and the testing was not progressed further.
The technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Project Context and Objectives:
In order to meet the challenges of the SAGE3 engine configurations in terms of robustness, environmental capability, size, functionality, performance, and reliability, all at reasonable cost, new technology sensors and effectors will be required.
Aero Engine Controls (AEC) has identified several new technologies that offer the potential to provide the necessary benefits to next generation fuel systems sensors and effectors, and also plans to broaden its activities searching for new technology opportunities. This programme is planned to develop these technologies (with specialist partners where they have the required technologies and skills) and evaluate the sensor and effector systems by bench and systems rigs demonstrators.
It should be that for sensor systems in particular, but also for effectors, the overall performance of the system is largely dependent on the performance of the electronics required to condition the sensor signals. AEC is a world leader in the supply of engine mounted electronics and is well positioned to work with specialist sensor suppliers to assess and evaluate electronic and overall systems performance levels that can realistically be achieved on engine. In addition to this, AEC can also realistically assess the weight, installation, reliability, and cost implications of the electronics and harnessing for all systems, in addition to the raw sensor attributes and limitations.
Several of the new technologies identified so far by AEC are considered to be in competition with each other, and are to be developed independently, or with different supplier partners. Although the competing supplier partners are aware of each other, no partners will have access to confidential data from the other suppliers. To this end the proposal below is split in each section along the lines of the different technologies to be developed and evaluated, with partners only having visibility of their own technologies
Specific objectives
AEC initiative sensors and effectors research and development
AEC identified acoustic technology as a potential technology that will provide significant benefits beyond the current state of the art.
AEC has identified forms of piezoelectric actuation that may provide significant benefits in terms of size, weight, reliability, and system architectural options over current torque motor servo-valve, stepper motor, and solenoid controlled systems.
M-E Eddy Current Position Sensor
M-E eddy current sensors are world leading in measurement performance (resolution, repeatability) and in the extreme compact design footprint. Development is upon existing sensor designs with external geometries of 2.5mm diameter x 3mm length. Discrete sensor coils have previously been integrated in ceramic housing for high pressure ratings (2000 bar). The sensor element is a single coil (2 wire), with output signal cable of 0.5mm diameter. The resulting mass of the sensor is very low, compared to existing technologies (LVDTs), and harnessing is significantly reduced.
For this project l M-E will implement a new sensor concept named Embedded Coil Technology (ECT). This represents a technological breakthrough in eddy current sensor design and manufacture, enabling the previous limitations of using eddy current sensors to be overcome. ECT will enable a single or dual sensor coil to be embedded in an inert organic compound producing a hermetically sealed sensor element, whose geometry can be extremely flexible. This provides almost unlimited scope in terms of the external design and geometrical shape of the sensor. This means the sensors can be adapted to suit virtually any application requirements.
ECT sensors additionally offer extreme mechanical robustness, resulting in very high MTBF intervals and much higher temperature stability. The sensors are also suitable for harsh operating environments, including high vibration, impact shocks and high operating temperatures as high as 350 deg C (with remote conditioning electronics).
Short range sensors with 1-2mm measurement range and exceptionally high resolution will be implemented by revising mechanical designs of metering valves in a combined M-E / AEC design activity. The sensor geometry is small enough to implement Shut Off Valve (SOV) and Pressure Drop Spill Valve (PDSV) monitoring (for fuel pump health monitoring) within current Fuel Metering Unit (FMU) bodies, significantly enhancing both robustness and reliability, and also enabling scheduled fuel pump maintenance.
Ultrasonic Acoustic Position Sensor
Piezoelectric technology is seen to offer key features that may provide great benefit to engine control systems. As a “solid state” technology piezoelectric devices are considered to have the potential for high reliability and long life. Two drawbacks with today’s commercial grade piezoelectric devices are the low strain and temperature limitations, with speciality high temperature devices prohibitively expensive. AEC has funded development in the field and has patented a material (trade marked as Thermiezo) which has high temperature capability and is currently being developed with the objective of providing significant improvement in strain compared to standard PZT based actuators.
Currently available ultrasonic position sensors have significant limitations due to their dependency on consistency of speed of sound in the media of transmission. The wide degree of variability of speed of sound in aerospace fuels due to chemical and environmental factors has up until now presented insuperable problems. AEC has identified at least one potential sensor mechanism whereby piezoelectric devices will be able to provide accurate position measurement from small numbers of low cost, small size and low weight sensors. This mechanism is now the subject of an AEC patent application, and requires demonstration in laboratory and systems environments.
The very small size of these sensors, combined with anticipated high reliability and environmental robustness, will enable size reductions to metering valve assemblies, shut-off valve monitoring, and variable geometry actuators on engine core. In addition these sensors will provide small, low cost opportunities for monitoring spill valve position and so providing health monitoring for fuel pumping systems.
AEC is currently funding research and development activities in support of these programmes in Newcastle University. Newcastle University will continue to be a source of expertise in these programmes, and the developing relationship with the university is seen as important to both AEC and Newcastle.
ORFS Mass Flow Sensor
Current fuel flow monitoring on engine typically employs a fixed pressure drop across a known flow number orifice for dynamic control, and bulkmeter flow measuring for more accurate, low bandwidth fuel consumption monitoring. Both these techniques comprise relatively large and heavy sub-systems, and neither is true mass flow. Small and reliable mass flow monitoring systems are required to enable new fuel system architectures capable of supporting new engine systems, including novel lean burn configurations, as well as providing necessary size and weight reductions in more conventional systems
ORFS has identified novel ultrasonic technology currently being used in advanced medical applications for mass flow measurement. Following initial investigations of the various possible technologies for mass flow measurement including, NMR, Coriolis, Venturi and Ultrasonic, very high frequency Ultrasonics is believed to provide a solution that meets all the criteria including accuracy , weight, no pressure drop, temperature and vibration. Recent developments in the use of ultrasonics in medical applications show that accurate ultrasonic flow meters can be very small and light weight. New techniques also enable the sensor to measure both laminar and turbulent flow.
Piezoelectric actuator mechanisms for direct drive and servo-systems
Piezoelectric technology is seen to offer key features that may provide great benefit to engine control systems. As a “solid state” technology piezoelectric devices are considered to have the potential for high reliability and long life. Two drawbacks with today’s commercial grade piezoelectric devices are the low strain and temperature limitations, with speciality high temperature devices prohibitively expensive. AEC has funded development in the field and has patented a material (trade marked as Thermiezo) which has high temperature capability and is currently being developed with the objective of potentially providing significant improvement in strain compared to standard PZT based actuators.
Piezoelectric actuators are believed to have the potential for increased reliability, reduced cost and weight servo-systems compared to modern fine wire devices such as torque motor driven servovalves for fuel system control.
As direct drive actuators some designs of piezo motors will result in smaller, more robust, and more reliable devices than current stepper motors and other aerospace alternatives. These devices will enable the development of engine core mounted fuel systems required for new engine functionality, as well as providing enhanced actuation for more conventional fuel metering unit architectures.
The high frequency response of piezoelectric devices also opens the door to long term development of very fast response engine fuel systems that may be applicable to technologies such as active combustion control.
Project Results:
1 Introduction
The work package descriptions of “JTI-CS-2010-4-SAGE-03-004” and the work carried out in response to the Description of Work is summarised in this report. The work was apportioned between AEC and the other partners in the CASE consortium as follows;
AEC - Management
Acoustic Sensor WP3
Piezoelectric Actuator WP5
Micro Epsilon - Eddy Current Sensor WP2
Oxford RF - Mass Flow Sensor WP4
2 Work Package Descriptions and Work Undertaken
Work Package 1 – Technologies Review
The Interim and Final Technologies review confirmed the initial selection of piezo acoustic displacement transducer, eddy current position transducer, and the piezo acoustic mass flow meter for demonstration in the CASE project. A thorough assessment of alternative implementations of piezo technology for effectors resulted in down selection of a piezo electric ring bender servovalve replacement. This device is considered to have the potential to be developed to provide a low cost, low weight, high reliability replacement to current generation servovalves used for FMU control.
Work Package 2 – Laboratory Demonstration
Laboratory demonstration tests of piezo-electric actuators were completed at Bath by 06 October 2012.
The Acoustic Sensor tests were completed at Morgan by 09 February 2011.
Work Package 3 - Systems Environmental Demonstrator
AEC tested individual component technologies such as piezo, mass flow sensor. The intent was to complete the environmental test as a block test but it was decided that this was not worthwhile above the components test.
Work Package 4 - Technology implementation
The sensor technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Work Package 5 - Eddy Current Sensor Definition
The Eddy Current sensor was proposed as a replacement for LVDTs used in current FMUs. Eddy current sensors can offer significant size, weight, measurement accuracy, speed and reliability benefits compared to current LVDT technology.
The preliminary specification definition concept for the Eddy Current Sensor was documented in June 2011.
Work Package 6 - Eddy Current Sensor Definition System Detailed Design
The Eddy current sensor coil geometry was completed in August 2011 and the FMEA risk management report was created on 11th December 2011.
Work Package 7 - Eddy Current Sensor Manufacture
ME delivered 2 off sensors to AEC in July 2013 for testing.
Work Package 8 - Acoustic Sensor; Laboratory Scale Definition System Demonstration
AEC worked with both Morgan and Newcastle to carry out proof of concept testing both in the laboratory and on an AEC test rig. The first generation sensor design consisted of two separate active elements in two separate housings, one of which had to be fitted at each end of a valve in order to measure the valve position.
Manufacture and population of the units was subcontracted to Morgan and delivered to AEC for testing.
The testing on the AEC test rig utilised the first generation sensor design and was limited to a range of temperatures around room temperature. The testing of the first generation sensor design identified issues with the method of mechanical attachment of the active sensor element, the piezo-ceramic, with the sensor housing and highlighted the critical nature of the method of mechanical attachment to the overall performance of the sensor.
Production of the test report was delayed due to resource issues .
Work Package 9 - Acoustic Sensor; Systems Environmental Demonstrators
The need for a second generation of sensor design was driven by AEC with the need to optimise the sensor packaging to make the sensor more compact and able to be fitted in a variety of different engine control applications. The second generation sensor combined the two previous active elements into a single housing that was only required to be fitted at one end of a fuel control valve in order to measure the valve position. Attempts to optimise the materials used to attach the piezo-ceramic material to the housing for use in an aero-engine environment over the complete range of conditions were not successful and it became clear that a new generation of sensor and further work would be required in order to provide a suitable sensor. However, AEC decided to carry on with a limited test programme using the second generation sensor design.
Unfortunately, due to the technical problems and delays in getting the test equipment and the test rig commissioned, the test programme was cancelled and the project was put on hold.
Work Package 10 - Acoustic Sensor; Implementation
See comments in 2.4
Work Package 11 – Mass Flow Sensor; Concept Development
Oxford RF Sensors were selected to develop a fuel mass flow measurement system using high frequency ultrasonic techniques as part of the CASE Project. The target was to take the first steps toward developing a device capable of deriving the mass flow rate of fuel from a measurement of two parameters:
i. The effective per unit mass velocity of fuel (and thus the volumetric flow rate through a
pipe of known cross section).
ii. The density of the fuel.
The proposal was that the two measurement tasks would first be addressed individually, with a view to subsequent integration into a single piece of hardware and accompanying electronics, and that the project would be carried out in 3 stages:
1. Concept development - extrapolating from other uses of ultrasonic acoustic techniques
to establishing the optimum size, frequencies and overall sensor dimensions.
2. Laboratory demonstration - building proof-of-concept demonstrators for evaluation
over limited environmental conditions.
3. Delivery of demonstrator unit to AEC for full systems environmental rig testing.
The concept work was completed and presented to AEC. The Report “Justified concept Recommendations” outlines the concepts proposed by ORFS.
Work Package 12 – Mass Flow Sensor; Laboratory Demonstration
ORFS presented a subsequent laboratory demonstration to AEC on 29th March 2012. Albeit at a low TRL level, the sensor systems presented by ORFS was considered to have the potential to be developed to aerospace engine fuel mass flow sensors.
Work Package 13 – Mass Flow Sensor; Systems Environmental Demonstrator
A low pressure proof-of-concept sensor capable of measuring volumetric flow rate (i) was demonstrated, operating with water as a test fluid. A density measurement module was also shown to be operating with some success at fixed temperature. However, it was agreed that this latter component of the mass flow measurement technology required substantial further development before it was appropriate to progress it to stage (3).
It was suggested that the volumetric flow rate sensor might be re-engineered for compatibility
with the AEC test rig and that this might be tested in July 2013 in conjunction with a
commercially available (but impractically large for real aerospace applications) density sensor.
However, it was judged that a more appropriate route would be to conclude the project at the
end of phase 2 and close the project.
Work Package 14 – Preliminary Actuator Concept Development
As described in the proposal a significant part of this activity is sub-contract to the University of Bath. An initial delay in the start of the project was due to the problems associated with appointment of a full time researcher.
The process started with a literature review which formed the first stage of the project and resulted in the issue of the Concepts overview document. This report looked at possible configurations of piezoceramic actuators and different valve types. There was then a down selection process which was defined as stage 2 and culminated in the production of the detailed concept report.
After discarding obvious non-starters, the detailed concept report described 5 concepts in more detail including an approximate sizing for each.
During the selection phase Bath and AEC jointly identified and assessed critical parameters (see appendix for scoring spread sheet and five concepts) for each of the five concepts.
The selection criteria with the largest weighting were:
• Failure mode
• Size
• Reliability
• Manufacturability/Complexity
There were some concerns and associated problems with all piezo concepts such as Encapsulation or protection from degradation of the piezoceramic by water. However, it was decided that these issues were not insurmountable and so could be addressed at a later stage in the project.
Work Package 15 – Laboratory Scale System Demonstration
Noliac’s ring bender (model number CMBR07) was selected for testing. During the selection phase of this project, this concept attained a higher score compared other piezoceramic structures.
Laboratory demonstrator tests were completed
Further work was required to investigate alternative clamping design options of the piezoelectric ring bender. This work was carried out during 2013.
Work Package 16 – Systems Environmental Demonstrators
During 2014 the prototype still had several issues that needed fixing and the temperature testing was planned but not completed by June 2014. To date this project is still ongoing and as such environmental testing was not completed under the Clean Sky CASE project.
Work Package 17 – Technology Implementation
The technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Work Package 18 – Consortium Management
The major activities of Consortium Management have been the successful synchronisation of the activities of the partners (ME and ORFS) and the predominant sub-contractors the Universities of Bath and Leeds, and Morgan Technical Ceramics based in Southampton.
Regular scheduled project meetings/communications structure:
a) Weekly telephone conversations and emails with partners and Morgan Technical Ceramics.
b) Reviews with the Clean Sky Assessor, David I. Jones, have been held regularly, usually face to face at the AEC site in Birmingham but occasionally via telecom. At these meetings the status of each work package and the deliverables have been discussed.
c) Monthly Programme Reviews have been held in Birmingham where the progress against plan and investment status are reviewed with the Research and Technology Director.
Potential Impact:
Dissemination/Exploitation of results, and IP management
The sensitive nature of the development meant that AEC was only able to disseminate to Rolls-Royce only at the Clean Sky Sage Interim and Annual reviews.
Exploitation
The main means of exploitation of the results is expected through the integration of the produced innovations to the SAGE programme and future engine developments. In line with the JTI main objectives it is expected that exploitation of results will occur in a very short period (less than 1 – 2 years) after the end of this project. Additionally, the participating partners will invest on the exploitation of such results through the industrialisation of the technology and prototypes developed within this project, offering to the aero engine market a well developed supply chain.
As AEC is not a sensor or effector manufacturer the exploitation of the technologies developed is a whole supply chain enterprise. The partners in this project will have the opportunities to exploit the technologies developed both within AEC fuel control systems, and also in other aerospace applications, and other aerospace companies. These alternative forms of exploitation will assist AEC by providing more product pull for the sensor and effector technologies and assist suppliers achieving critical mass.
AEC also sub-contracted minor work packages to other specialist companies. Noliac in Denmark is a specialist design and manufacturing company with whom AEC has worked before, and Noliac has specialist capabilities that AEC accessed. This helped to develop the technology base within the small companies involved, and also develop the company as a potential supply chain for finished product.
List of Websites:
no website
Aero Engine Controls (AEC) identified several new technologies that offer the potential to provide the benefits to next generation fuel systems sensors and effectors.
This programme planned to develop these technologies independently of each other with Partners within the Consortium, specifically;
Acoustic Sensor (AEC)
AEC worked with both Morgan and Newcastle to carry out analysis and testing to confirm the proof of concept of the units both in the laboratory and on an AEC test rig (referred to as the first generation sensor). Testing of the first generation sensor design identified issues with the method of mechanical attachment of the active sensor element (the piezo-ceramic), as such a second generation sensor was designed by AEC, with the need to optimise the sensor packaging to make the sensor more compact and able to be fitted in a variety of different engine control applications. Unfortunately, testing proved that the second generation sensor was still not successful and as such further test programmes were put on hold and would be evaluated at a later date.
Piezoelectric Sensor (AEC)
A significant part of this activity was sub-contracted to the University of Bath. Five concepts were developed and the parties agreed that the Noliac ringbender was the suitable option. Laboratory demonstrator tests were completed and further investigation was required to look at suitable clamping options.
During 2014 the prototype still had several issues that needed fixing and the temperature testing was planned but not completed by June 2014.
Mass Flow Sensor (Oxford RF)
Oxford RF Sensors were selected to develop a fuel mass flow measurement system using high frequency ultrasonic techniques. Initial tests at Oxford RF showed that the sensor had potential for further development; however, after further testing of the mass flow measurement technology, it was considered that the project required substantial further development before it was appropriate to progress and as such the project was put on hold.
Eddy Current Sensor (Micro Epsilon)
The Eddy Current sensor was proposed as a replacement for Linear Variable Differential Transformers (“LVDTs”) used in current Fuel Metering Units. Eddy current sensors can offer significant size, weight, measurement accuracy, speed and reliability benefits compared to current LVDT technology. Micro Epsilon delivered 2 off sensors to AEC for testing. The intent was to complete the environmental test as a block test but it was decided that this was not be worthwhile above the components test and the testing was not progressed further.
The technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Project Context and Objectives:
In order to meet the challenges of the SAGE3 engine configurations in terms of robustness, environmental capability, size, functionality, performance, and reliability, all at reasonable cost, new technology sensors and effectors will be required.
Aero Engine Controls (AEC) has identified several new technologies that offer the potential to provide the necessary benefits to next generation fuel systems sensors and effectors, and also plans to broaden its activities searching for new technology opportunities. This programme is planned to develop these technologies (with specialist partners where they have the required technologies and skills) and evaluate the sensor and effector systems by bench and systems rigs demonstrators.
It should be that for sensor systems in particular, but also for effectors, the overall performance of the system is largely dependent on the performance of the electronics required to condition the sensor signals. AEC is a world leader in the supply of engine mounted electronics and is well positioned to work with specialist sensor suppliers to assess and evaluate electronic and overall systems performance levels that can realistically be achieved on engine. In addition to this, AEC can also realistically assess the weight, installation, reliability, and cost implications of the electronics and harnessing for all systems, in addition to the raw sensor attributes and limitations.
Several of the new technologies identified so far by AEC are considered to be in competition with each other, and are to be developed independently, or with different supplier partners. Although the competing supplier partners are aware of each other, no partners will have access to confidential data from the other suppliers. To this end the proposal below is split in each section along the lines of the different technologies to be developed and evaluated, with partners only having visibility of their own technologies
Specific objectives
AEC initiative sensors and effectors research and development
AEC identified acoustic technology as a potential technology that will provide significant benefits beyond the current state of the art.
AEC has identified forms of piezoelectric actuation that may provide significant benefits in terms of size, weight, reliability, and system architectural options over current torque motor servo-valve, stepper motor, and solenoid controlled systems.
M-E Eddy Current Position Sensor
M-E eddy current sensors are world leading in measurement performance (resolution, repeatability) and in the extreme compact design footprint. Development is upon existing sensor designs with external geometries of 2.5mm diameter x 3mm length. Discrete sensor coils have previously been integrated in ceramic housing for high pressure ratings (2000 bar). The sensor element is a single coil (2 wire), with output signal cable of 0.5mm diameter. The resulting mass of the sensor is very low, compared to existing technologies (LVDTs), and harnessing is significantly reduced.
For this project l M-E will implement a new sensor concept named Embedded Coil Technology (ECT). This represents a technological breakthrough in eddy current sensor design and manufacture, enabling the previous limitations of using eddy current sensors to be overcome. ECT will enable a single or dual sensor coil to be embedded in an inert organic compound producing a hermetically sealed sensor element, whose geometry can be extremely flexible. This provides almost unlimited scope in terms of the external design and geometrical shape of the sensor. This means the sensors can be adapted to suit virtually any application requirements.
ECT sensors additionally offer extreme mechanical robustness, resulting in very high MTBF intervals and much higher temperature stability. The sensors are also suitable for harsh operating environments, including high vibration, impact shocks and high operating temperatures as high as 350 deg C (with remote conditioning electronics).
Short range sensors with 1-2mm measurement range and exceptionally high resolution will be implemented by revising mechanical designs of metering valves in a combined M-E / AEC design activity. The sensor geometry is small enough to implement Shut Off Valve (SOV) and Pressure Drop Spill Valve (PDSV) monitoring (for fuel pump health monitoring) within current Fuel Metering Unit (FMU) bodies, significantly enhancing both robustness and reliability, and also enabling scheduled fuel pump maintenance.
Ultrasonic Acoustic Position Sensor
Piezoelectric technology is seen to offer key features that may provide great benefit to engine control systems. As a “solid state” technology piezoelectric devices are considered to have the potential for high reliability and long life. Two drawbacks with today’s commercial grade piezoelectric devices are the low strain and temperature limitations, with speciality high temperature devices prohibitively expensive. AEC has funded development in the field and has patented a material (trade marked as Thermiezo) which has high temperature capability and is currently being developed with the objective of providing significant improvement in strain compared to standard PZT based actuators.
Currently available ultrasonic position sensors have significant limitations due to their dependency on consistency of speed of sound in the media of transmission. The wide degree of variability of speed of sound in aerospace fuels due to chemical and environmental factors has up until now presented insuperable problems. AEC has identified at least one potential sensor mechanism whereby piezoelectric devices will be able to provide accurate position measurement from small numbers of low cost, small size and low weight sensors. This mechanism is now the subject of an AEC patent application, and requires demonstration in laboratory and systems environments.
The very small size of these sensors, combined with anticipated high reliability and environmental robustness, will enable size reductions to metering valve assemblies, shut-off valve monitoring, and variable geometry actuators on engine core. In addition these sensors will provide small, low cost opportunities for monitoring spill valve position and so providing health monitoring for fuel pumping systems.
AEC is currently funding research and development activities in support of these programmes in Newcastle University. Newcastle University will continue to be a source of expertise in these programmes, and the developing relationship with the university is seen as important to both AEC and Newcastle.
ORFS Mass Flow Sensor
Current fuel flow monitoring on engine typically employs a fixed pressure drop across a known flow number orifice for dynamic control, and bulkmeter flow measuring for more accurate, low bandwidth fuel consumption monitoring. Both these techniques comprise relatively large and heavy sub-systems, and neither is true mass flow. Small and reliable mass flow monitoring systems are required to enable new fuel system architectures capable of supporting new engine systems, including novel lean burn configurations, as well as providing necessary size and weight reductions in more conventional systems
ORFS has identified novel ultrasonic technology currently being used in advanced medical applications for mass flow measurement. Following initial investigations of the various possible technologies for mass flow measurement including, NMR, Coriolis, Venturi and Ultrasonic, very high frequency Ultrasonics is believed to provide a solution that meets all the criteria including accuracy , weight, no pressure drop, temperature and vibration. Recent developments in the use of ultrasonics in medical applications show that accurate ultrasonic flow meters can be very small and light weight. New techniques also enable the sensor to measure both laminar and turbulent flow.
Piezoelectric actuator mechanisms for direct drive and servo-systems
Piezoelectric technology is seen to offer key features that may provide great benefit to engine control systems. As a “solid state” technology piezoelectric devices are considered to have the potential for high reliability and long life. Two drawbacks with today’s commercial grade piezoelectric devices are the low strain and temperature limitations, with speciality high temperature devices prohibitively expensive. AEC has funded development in the field and has patented a material (trade marked as Thermiezo) which has high temperature capability and is currently being developed with the objective of potentially providing significant improvement in strain compared to standard PZT based actuators.
Piezoelectric actuators are believed to have the potential for increased reliability, reduced cost and weight servo-systems compared to modern fine wire devices such as torque motor driven servovalves for fuel system control.
As direct drive actuators some designs of piezo motors will result in smaller, more robust, and more reliable devices than current stepper motors and other aerospace alternatives. These devices will enable the development of engine core mounted fuel systems required for new engine functionality, as well as providing enhanced actuation for more conventional fuel metering unit architectures.
The high frequency response of piezoelectric devices also opens the door to long term development of very fast response engine fuel systems that may be applicable to technologies such as active combustion control.
Project Results:
1 Introduction
The work package descriptions of “JTI-CS-2010-4-SAGE-03-004” and the work carried out in response to the Description of Work is summarised in this report. The work was apportioned between AEC and the other partners in the CASE consortium as follows;
AEC - Management
Acoustic Sensor WP3
Piezoelectric Actuator WP5
Micro Epsilon - Eddy Current Sensor WP2
Oxford RF - Mass Flow Sensor WP4
2 Work Package Descriptions and Work Undertaken
Work Package 1 – Technologies Review
The Interim and Final Technologies review confirmed the initial selection of piezo acoustic displacement transducer, eddy current position transducer, and the piezo acoustic mass flow meter for demonstration in the CASE project. A thorough assessment of alternative implementations of piezo technology for effectors resulted in down selection of a piezo electric ring bender servovalve replacement. This device is considered to have the potential to be developed to provide a low cost, low weight, high reliability replacement to current generation servovalves used for FMU control.
Work Package 2 – Laboratory Demonstration
Laboratory demonstration tests of piezo-electric actuators were completed at Bath by 06 October 2012.
The Acoustic Sensor tests were completed at Morgan by 09 February 2011.
Work Package 3 - Systems Environmental Demonstrator
AEC tested individual component technologies such as piezo, mass flow sensor. The intent was to complete the environmental test as a block test but it was decided that this was not worthwhile above the components test.
Work Package 4 - Technology implementation
The sensor technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Work Package 5 - Eddy Current Sensor Definition
The Eddy Current sensor was proposed as a replacement for LVDTs used in current FMUs. Eddy current sensors can offer significant size, weight, measurement accuracy, speed and reliability benefits compared to current LVDT technology.
The preliminary specification definition concept for the Eddy Current Sensor was documented in June 2011.
Work Package 6 - Eddy Current Sensor Definition System Detailed Design
The Eddy current sensor coil geometry was completed in August 2011 and the FMEA risk management report was created on 11th December 2011.
Work Package 7 - Eddy Current Sensor Manufacture
ME delivered 2 off sensors to AEC in July 2013 for testing.
Work Package 8 - Acoustic Sensor; Laboratory Scale Definition System Demonstration
AEC worked with both Morgan and Newcastle to carry out proof of concept testing both in the laboratory and on an AEC test rig. The first generation sensor design consisted of two separate active elements in two separate housings, one of which had to be fitted at each end of a valve in order to measure the valve position.
Manufacture and population of the units was subcontracted to Morgan and delivered to AEC for testing.
The testing on the AEC test rig utilised the first generation sensor design and was limited to a range of temperatures around room temperature. The testing of the first generation sensor design identified issues with the method of mechanical attachment of the active sensor element, the piezo-ceramic, with the sensor housing and highlighted the critical nature of the method of mechanical attachment to the overall performance of the sensor.
Production of the test report was delayed due to resource issues .
Work Package 9 - Acoustic Sensor; Systems Environmental Demonstrators
The need for a second generation of sensor design was driven by AEC with the need to optimise the sensor packaging to make the sensor more compact and able to be fitted in a variety of different engine control applications. The second generation sensor combined the two previous active elements into a single housing that was only required to be fitted at one end of a fuel control valve in order to measure the valve position. Attempts to optimise the materials used to attach the piezo-ceramic material to the housing for use in an aero-engine environment over the complete range of conditions were not successful and it became clear that a new generation of sensor and further work would be required in order to provide a suitable sensor. However, AEC decided to carry on with a limited test programme using the second generation sensor design.
Unfortunately, due to the technical problems and delays in getting the test equipment and the test rig commissioned, the test programme was cancelled and the project was put on hold.
Work Package 10 - Acoustic Sensor; Implementation
See comments in 2.4
Work Package 11 – Mass Flow Sensor; Concept Development
Oxford RF Sensors were selected to develop a fuel mass flow measurement system using high frequency ultrasonic techniques as part of the CASE Project. The target was to take the first steps toward developing a device capable of deriving the mass flow rate of fuel from a measurement of two parameters:
i. The effective per unit mass velocity of fuel (and thus the volumetric flow rate through a
pipe of known cross section).
ii. The density of the fuel.
The proposal was that the two measurement tasks would first be addressed individually, with a view to subsequent integration into a single piece of hardware and accompanying electronics, and that the project would be carried out in 3 stages:
1. Concept development - extrapolating from other uses of ultrasonic acoustic techniques
to establishing the optimum size, frequencies and overall sensor dimensions.
2. Laboratory demonstration - building proof-of-concept demonstrators for evaluation
over limited environmental conditions.
3. Delivery of demonstrator unit to AEC for full systems environmental rig testing.
The concept work was completed and presented to AEC. The Report “Justified concept Recommendations” outlines the concepts proposed by ORFS.
Work Package 12 – Mass Flow Sensor; Laboratory Demonstration
ORFS presented a subsequent laboratory demonstration to AEC on 29th March 2012. Albeit at a low TRL level, the sensor systems presented by ORFS was considered to have the potential to be developed to aerospace engine fuel mass flow sensors.
Work Package 13 – Mass Flow Sensor; Systems Environmental Demonstrator
A low pressure proof-of-concept sensor capable of measuring volumetric flow rate (i) was demonstrated, operating with water as a test fluid. A density measurement module was also shown to be operating with some success at fixed temperature. However, it was agreed that this latter component of the mass flow measurement technology required substantial further development before it was appropriate to progress it to stage (3).
It was suggested that the volumetric flow rate sensor might be re-engineered for compatibility
with the AEC test rig and that this might be tested in July 2013 in conjunction with a
commercially available (but impractically large for real aerospace applications) density sensor.
However, it was judged that a more appropriate route would be to conclude the project at the
end of phase 2 and close the project.
Work Package 14 – Preliminary Actuator Concept Development
As described in the proposal a significant part of this activity is sub-contract to the University of Bath. An initial delay in the start of the project was due to the problems associated with appointment of a full time researcher.
The process started with a literature review which formed the first stage of the project and resulted in the issue of the Concepts overview document. This report looked at possible configurations of piezoceramic actuators and different valve types. There was then a down selection process which was defined as stage 2 and culminated in the production of the detailed concept report.
After discarding obvious non-starters, the detailed concept report described 5 concepts in more detail including an approximate sizing for each.
During the selection phase Bath and AEC jointly identified and assessed critical parameters (see appendix for scoring spread sheet and five concepts) for each of the five concepts.
The selection criteria with the largest weighting were:
• Failure mode
• Size
• Reliability
• Manufacturability/Complexity
There were some concerns and associated problems with all piezo concepts such as Encapsulation or protection from degradation of the piezoceramic by water. However, it was decided that these issues were not insurmountable and so could be addressed at a later stage in the project.
Work Package 15 – Laboratory Scale System Demonstration
Noliac’s ring bender (model number CMBR07) was selected for testing. During the selection phase of this project, this concept attained a higher score compared other piezoceramic structures.
Laboratory demonstrator tests were completed
Further work was required to investigate alternative clamping design options of the piezoelectric ring bender. This work was carried out during 2013.
Work Package 16 – Systems Environmental Demonstrators
During 2014 the prototype still had several issues that needed fixing and the temperature testing was planned but not completed by June 2014. To date this project is still ongoing and as such environmental testing was not completed under the Clean Sky CASE project.
Work Package 17 – Technology Implementation
The technologies are being considered for possible applications on the next engine platforms and / or further technology development programmes, for example, piezo devices are being considered for a servo valve replacement as part of a UK specific funded activity.
Work Package 18 – Consortium Management
The major activities of Consortium Management have been the successful synchronisation of the activities of the partners (ME and ORFS) and the predominant sub-contractors the Universities of Bath and Leeds, and Morgan Technical Ceramics based in Southampton.
Regular scheduled project meetings/communications structure:
a) Weekly telephone conversations and emails with partners and Morgan Technical Ceramics.
b) Reviews with the Clean Sky Assessor, David I. Jones, have been held regularly, usually face to face at the AEC site in Birmingham but occasionally via telecom. At these meetings the status of each work package and the deliverables have been discussed.
c) Monthly Programme Reviews have been held in Birmingham where the progress against plan and investment status are reviewed with the Research and Technology Director.
Potential Impact:
Dissemination/Exploitation of results, and IP management
The sensitive nature of the development meant that AEC was only able to disseminate to Rolls-Royce only at the Clean Sky Sage Interim and Annual reviews.
Exploitation
The main means of exploitation of the results is expected through the integration of the produced innovations to the SAGE programme and future engine developments. In line with the JTI main objectives it is expected that exploitation of results will occur in a very short period (less than 1 – 2 years) after the end of this project. Additionally, the participating partners will invest on the exploitation of such results through the industrialisation of the technology and prototypes developed within this project, offering to the aero engine market a well developed supply chain.
As AEC is not a sensor or effector manufacturer the exploitation of the technologies developed is a whole supply chain enterprise. The partners in this project will have the opportunities to exploit the technologies developed both within AEC fuel control systems, and also in other aerospace applications, and other aerospace companies. These alternative forms of exploitation will assist AEC by providing more product pull for the sensor and effector technologies and assist suppliers achieving critical mass.
AEC also sub-contracted minor work packages to other specialist companies. Noliac in Denmark is a specialist design and manufacturing company with whom AEC has worked before, and Noliac has specialist capabilities that AEC accessed. This helped to develop the technology base within the small companies involved, and also develop the company as a potential supply chain for finished product.
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