Final Report Summary - INAIPS (Innovative aircraft ice protection system – sensing and modelling)
Executive Summary:
The wing of an aircraft is a key component to improved noise and efficiency characteristics of today's air transport. Yet, airplane wings are prone to and adversely affected by the formation of ice on their surface, which seriously compromises flight safety. The detection of ice on the wing surface and the existence of a reliable de-icing concept are therefore essential, especially for new laminar wing concepts that are particularly sensitive to the presence of ice.
Whilst current ice-detection systems use a remotely mounted probe to assess ice accretion, the approach of the Clean Sky JU project InAIPS is based on aero-conformal optical ice detection sensors, which are integrated directly into the leading edge of the wing at the relevant portions for ice accretion. The project tackles the problem of ice-accretion on a laminar flow wing with a semi-empirical approach, using measurements as well as mathematical modelling. The developed system model is assembled of data from the optical sensors, an ice detection algorithm determining ice thickness and ice type from the sensor data, and aerodynamic simulations to estimate the lift and drag forces on the wing section.
The response of the sensors to the ice accretion is measured as an electrical signal which depends on the intensity of reflections and backscattering from the ice. To capture the ice accretion under different flight conditions in terms of angle of attack, two optical sensors are installed on the wing, one on the stagnation line looking forward and the other angled upwards. The signals are then processed with an Ensemble-Kalman-filter based algorithm, which translates the signal into ice thickness and ice type, the latter depending on the outside air temperature. From data constituted from wind tunnel experiments within the project, a best estimate for the corresponding ice shape and angle of attack is determined. Based on this information, lift and drag forces on the wing sections including ice are evaluated using CFD simulations. With this information, the impact of the icing at a wing section on the asymmetry of the wing can be assessed under different flight conditions.
In conjunction with the aero-conformal ice detector developed in the EU FP7 projects ACIDS and ON-WINGS, the evaluation of the ice shapes in different flight conditions and the simulations of their impact on the aerodynamic behaviour of the entire airplane enable the setup of a full system model for ice accretion and ice detection. Putting all pieces together a system model for icing and its impact on the wing performance is attained. In combination with a de-icing process it is an approach to a primary, closed-loop control system for ice protection.
Project Context and Objectives:
The advancement of low noise, low emission, and safe air transport is one of the most urgent requirements in the area of transportation. With continuously growing personal and economic mobility the demands of efficient transportation increase. The wing of an aircraft is a key component to improved noise and efficiency characteristics of today's air transport. Yet, airplane wings are prone to and adversely affected by the formation of ice on their surface, which seriously addresses flight safety. Ice accretion may lead to a complete loss of control or disrupt the lift to a level insufficient to keep the aircraft airborne. De-icing therefore is essential, in particular for new laminar wing concepts that are particularly sensitive to the presence of ice. Novel design of wings, as well as the demand for reliable and energy efficient de-icing require the development and assessment of novel de-icing concepts. In the context of ice protection system, the reliable detection of the accreted ice on the wing surface is a key component for both safety and efficiency. On the one hand, an ice detection system indicates whether de-icing should be switched on for the iced section of the wing before the ice can affect flight safety, on the other hand a good system may contribute to avoid unnecessary de-icing and thus a waste of energy or damage to the wing.
Ice-detection by remote probes, as used in most common systems is not able to fulfil these requirements sufficiently. More successfully the issues of safety and efficiency can be tackled by optical ice detection sensors, which are integrated directly into the leading edge of the wing at the relevant portions for ice accretion. The approach of the Clean Sky JU project InAIPS is based on such a sensing system.
The overall aim of the project is a novel approach for improved ice detection and automatic assessment of the potential impact of icing on the drag and lift characteristics of the wing. The project topic therefore addresses three main objectives:
1. Development of a system model for the investigation of ice detection and ice protection;
2. Development and refinement of innovative sensing options for ice detection to support active ice protection systems;
3. Aerodynamic modelling to investigate the impact of icing on the flight properties.
Project Results:
The main objective of the project is a system model for ice detection on laminar flow wings and their impact on the aerodynamic characteristics of the aircraft. The approach as well as the main results and achievements towards this goal are described in the following:
General idea of the system model
Current ice detectors are usually located remote from the critical aerodynamic surfaces (such as the wing) and as such can lead to the ice protection system being triggered in an inefficient manner by activating it long before ice actually starts forming on the wing. The detection of ice on the wing surface, especially for new laminar wing concepts that are particularly sensitive to the presence of ice, therefore allows a more efficient use of the IPS by only activating it when it is needed. To overcome the remote location of current ice-detection systems, the approach of the Clean Sky project InAIPS is based on aero-conformal optical ice detection sensors which are integrated directly into the leading edge of the wing at the relevant positions. The sensor signals are then translated to ice thickness and ice type using an algorithm based on an Ensemble-Kalman Filter technique. The sensing technology and the dedicated algorithm were first developed in the EU FP7 project ON-WINGS. The InAIPS objective goes beyond the ON-WINGS approach by using several sensors and integrating them in a system model which combines the information on the ice accretion with aerodynamic simulations. The final model can be used to assess the impact of the icing of a wing section on the general aerodynamic asymmetry of the aircraft for various flight conditions.
Ice detection sensor technology
In the InAIPS project two different types of ice detection sensors were developed. The first type relies on detecting the backscatter and reflected of light from the ice volume using a fibre array geometry. This sensor type was mounted in two positions on the leading edge of the laminar flow wing, one on the stagnation line and the other one on upper surface of the leading. The second type of sensor was a surface-mounted quasi-distributed ice sensor relying on optical losses induced by the presence of ice on the surface of the wing.
The array fibre sensor consists of a central source fibre and three signal fibres on either side and is a further development of the ice sensor originally developed in the ACIDS and ON-WINGS projects. The further development of this technology undertaken in the InAIPS project was the optimization of a similar sensor architecture for the specific needs of this project, namely the detection of very thin ice, which is particularly disruptive to the laminar flow of the wing.
In addition to the array fibre optical sensors, a distributed ice/no ice sensor was installed to indicate the existence of ice behind the erosion shield. The sensor, in this flash format, is a new development and was tested in InAIPS for the first time. It consists of four sensor units, which were integrated in different glass fibres and a light source fibre. The sensor assembly was mounted on the upper surface of the wing inside a groove specially designed to house the sensor.
The distributed ice sensor was an experimental sensor and as such there is still a need for further development. It performed well in the lab experiments, but when located on the wing, it was not possible to position it in a high ice accreting area, without affecting the airflow and consequently it did not reveal its full potential. In fact some ice was accreting and then flaking off, giving a very erratic signal response which was thus inconclusive.
Data acquisition system
The signal data measured by the sensors is collected by a data acquisition system constituted of an optical interface with 24 photodiodes. The signal transfer from the sensors is realized through ST/PC fibre optical connectors. The data are transferred to a host PC and handed to the post-processing software via a USB port.
Ice detection algorithm
The signals from the optical fibres in the sensors collected by the acquisition system are processed by an ice detection algorithm, which translates the signals to thicknesses based on an Ensemble Kalman-Filter (EKF) technique. The underlying algorithm was first developed during the FP7 project ON-WINGS. In the InAIPS project, the algorithm was tested in coincidence for both array sensors. The ice thicknesses measured during the icing wind tunnel tests serve as basis for a look-up-table (LUT), to determine the thickness from the measured intensity and evaluate the corresponding outside air temperature.
Validation of the methodology showed good performance for the determination of the ice thickness. For the evaluation of the ice type and the corresponding outside air temperature it had some shortcomings at glaze ice conditions, i.e. higher temperatures.
The performance of the methodology is to a large extent constrained by the quality of the LUT, which is compiled from the data acquired during the InAIPS wind tunnel tests. By performing tests for the same conditions repeatedly and covering a range of temperatures and angles of attack, a good set of data could be obtained. Nevertheless, the parameter space is limited. Independency of such LUTs could be reached by using a physical model of the photon intensity to derive ice parameters from the backscattered intensities. The time frame of the InAIPS project did not allow the development and validation of such a model, but these tasks could be subject to possible follow-up activities.
CFD simulations
The shape of the laminar flow wing was used as input geometry for computational fluid dynamics (CFD) simulations to investigate the lift and drag forces on the aerofoil section. The incompressible, stationary simulations were carried out with a Spalart-Allmaras model that was run with an RANS solver. After first simulations with the ice-free wing geometry, sensitivity tests with generic ice shapes of different size and under different conditions were carried out and analysed. When a first set of measurement data had been obtained during the ice tunnel tests in August 2014, the real ice shapes were digitized and their geometry was meshed. The geometries were used to carry out CFD simulations for the iced wing section under the same conditions as for the ice tunnel measurements. By visual inspection and by analysis of the section lift and drag coefficients, the influence of the icing on the flow characteristics under different angles of attack, temperatures, and ice shapes was investigated.
System model
Based on the developments on the sensor, the ice detection model and the CFD simulation, the system model was constituted from the pieces described before.
The functionality of the model can be summarized as follows: The raw data from the optical sensors is fed to the EKF algorithm which translates the intensities to ice thicknesses and evaluates ice type and outside air temperature based on the progress of the intensity signal with ice growth.
From the ice thicknesses detected by both sensors, other parameters can be derived. Factors including the icing conditions and the wing’s angle of attack cause ice to accrete unevenly around the wing’s leading edge, i.e. for a positive angle of attack, more ice accretes on the lower edge of the wing, and vice versa. Therefore, the thickness ratio (TR) of the forward looking sensor and the upward looking sensor is a good indicator for the angle of attack and gives a best guess for the shape of the ice. Although there is a clear relationship between the angle of attack and the accreted ice shape for the InAIPS aerofoil profile, this is not necessarily true for all aerofoils.
Based on the ratio of the thicknesses measured by the setup of the optical sensors, the ice shape is determined and the corresponding CFD simulation determines the lift and drag on the aerofoil.
The final system model should give an estimate of the ice layer’s current influence on the aircraft’s aerodynamic behaviour. Therefore, a linear shrinking algorithm has been applied to calculate ice profiles of different thickness from the original shapes. These are used to perform ice thickness dependent CFD simulations on characteristic shapes from the icing tunnel tests. The results of these CFD simulations are the lift and drag coefficients of the iced airfoil section for different ice thicknesses.
The results have shown strong dependencies of lift and drag on the ice thickness. Even for a thin layer of ice the effect can be immense. The decrease of the lift and increase of the drag is particularly large for climb flight conditions.
The model was finally extended to the assessment of the aircraft’s wing asymmetry due to icing. Ice accreted on an aircraft’s wing can have a strong influence on the aircraft’s aerodynamics. A strong asymmetric behavior can even render the aircraft difficult to control. Therefore, based on the information on the ice thickness, one can assess the force asymmetry and therewith the rolling and yawing moments on the aircraft, which is described in the following. These considerations are used to estimate the discussed quantities in the Matlab/Simulink tool (see next section).
Graphical User Interface
An existing Matlab/Simulink tool for system model testing has been further advanced for the purposes in InAIPS. The user has the possibility to indicate the iced section on the aircraft and the GUI shows the total calculated lift and drag for the aircraft and also indicates the change with respect to the ice free lift and drag in percent. The system further calculates the resulting rolling and yawing moment. The lower left panel visualises the behaviour of the de-icing heater system. The lower right panel shows the control variables.
The evaluation of the total lift and drag forces on the wing as well as the rolling and yawing moments allows to assess how critical the icing of a wing section is for the flight characteristics of the laminar flow wing, or, in the context of an Ice Protection System (IPS), how critical the failure of a certain de-icing section would be. The system model is thus a useful tool to investigate the number of independent de-icing zones needed to ensure flight safety even in the case of partial failure of one or more zones
Potential Impact:
Summary of the dissemination activities
The InAIPS project team has successfully developed a system model for the aero-conformal detection of ice on a laminar wing surface and its impact on the flow characteristics. The sensing technology developed in the predecessor EU FP7 project ON-WINGS was further developed and improved, in particular for the detection of thin ice layers.
The project partners have undertaken different activities for dissemination of the project results. The ice detection technology integrated in the wing model was exhibited together with a live demonstration of its functionality on the Airtec fair 2014 in Frankfurt a.M. Germany. At the same place, an oral presentation on the preliminary results of the project was given by TWT at the corresponding Airtec conference.
The consortium futher proposed the project to the Clean Sky office for exhibition and presentation at the upcoming Aerodays in autumn 2015.
These dissemination activities strongly contribute to promote the technology and catch a wider audience’s interest in the InAIPS results.
Impact of the InAIPS results
The project InAIPS will create a strong impact on the European Aircraft sector, by addressing de-icing capabilities as an important safety-critical aspect of aircrafts in the context of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator. Focusing on the overall aim of a novel approach for improved ice detection and automatic assessment of the potential impact of icing on the drag and lift characteristics of the wing in all flight phases, the project results will have an impact on important aspects in the ACARE and CleanSky objectives. The semi-empirical system model developed in InAIPS represents an efficient methodology to approach the challenges.
Since a reliable ice detection method as advanced in InAIPS tackles the issue of energy and fuel burning efficiency from the beginning on, the project contributes on building up a strong European position for the given challenges of exploiting the green aviation domain. Building on comprehensive sensing and modelling the project results are an important step towards a closed loop approach for aircraft ice protection and thus contributes to strengthen the European leadership in cross-cutting technologies. The integrated use of advanced modelling techniques in the aeronautical domain moreover will leverage the overall application of digital design towards more and effective solutions in the frame of optimising air transport.
Addressing the overall mission of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator, the activity will derive a beneficial combination of techniques for reaching the overall SFWA goals. The straight-forward approach of InAIPS supports high-quality ice protection systems for also illuminating the energy aspects within scope of reducing the energy footprint.
In addition to helping to achieve CSJUs overall SFWA targets, this activity will strengthen the position of European Aircraft development in an ever more competitive world market. As Europe is among the leaders in striving for CO2 emission reduction and cleaner transport, this competitive advantage will become even more beneficial when other markets turn their gaze upon Green Aviation.
To summarize, in the InAIPS project, essential aspects for a full deployment of novel wing architecture in the context of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator are investigated. The project results set the stage for the following array of impacts.
• The development of the InAIPS system model builds a comprehensive basis for assessing and optimizing the performance of ice protection systems addressing flight safety and energy awareness.
• The sensing technologies developed and refined in InAIPS represent an accurate and reliable system for ice detection and thus provide an important contribution to safer aircraft configurations.
• Due to the development of innovative sensing options to support the active ice protection strategy, an important aspect for intelligent systems in the aviation domain is addressed. The concept of supervision and sensing can then be enhanced for other aspects within the aircraft, e.g. cabin air-conditioning, using different sensors.
Hence, the project results contribute to building towards a strong European case for the upcoming challenges of exploiting the aviation domain. They bring added dimensions of flight testing capability and sensor technology and contribute to the overall reduction of fuel consumption and CO2 emissions.
The wing of an aircraft is a key component to improved noise and efficiency characteristics of today's air transport. Yet, airplane wings are prone to and adversely affected by the formation of ice on their surface, which seriously compromises flight safety. The detection of ice on the wing surface and the existence of a reliable de-icing concept are therefore essential, especially for new laminar wing concepts that are particularly sensitive to the presence of ice.
Whilst current ice-detection systems use a remotely mounted probe to assess ice accretion, the approach of the Clean Sky JU project InAIPS is based on aero-conformal optical ice detection sensors, which are integrated directly into the leading edge of the wing at the relevant portions for ice accretion. The project tackles the problem of ice-accretion on a laminar flow wing with a semi-empirical approach, using measurements as well as mathematical modelling. The developed system model is assembled of data from the optical sensors, an ice detection algorithm determining ice thickness and ice type from the sensor data, and aerodynamic simulations to estimate the lift and drag forces on the wing section.
The response of the sensors to the ice accretion is measured as an electrical signal which depends on the intensity of reflections and backscattering from the ice. To capture the ice accretion under different flight conditions in terms of angle of attack, two optical sensors are installed on the wing, one on the stagnation line looking forward and the other angled upwards. The signals are then processed with an Ensemble-Kalman-filter based algorithm, which translates the signal into ice thickness and ice type, the latter depending on the outside air temperature. From data constituted from wind tunnel experiments within the project, a best estimate for the corresponding ice shape and angle of attack is determined. Based on this information, lift and drag forces on the wing sections including ice are evaluated using CFD simulations. With this information, the impact of the icing at a wing section on the asymmetry of the wing can be assessed under different flight conditions.
In conjunction with the aero-conformal ice detector developed in the EU FP7 projects ACIDS and ON-WINGS, the evaluation of the ice shapes in different flight conditions and the simulations of their impact on the aerodynamic behaviour of the entire airplane enable the setup of a full system model for ice accretion and ice detection. Putting all pieces together a system model for icing and its impact on the wing performance is attained. In combination with a de-icing process it is an approach to a primary, closed-loop control system for ice protection.
Project Context and Objectives:
The advancement of low noise, low emission, and safe air transport is one of the most urgent requirements in the area of transportation. With continuously growing personal and economic mobility the demands of efficient transportation increase. The wing of an aircraft is a key component to improved noise and efficiency characteristics of today's air transport. Yet, airplane wings are prone to and adversely affected by the formation of ice on their surface, which seriously addresses flight safety. Ice accretion may lead to a complete loss of control or disrupt the lift to a level insufficient to keep the aircraft airborne. De-icing therefore is essential, in particular for new laminar wing concepts that are particularly sensitive to the presence of ice. Novel design of wings, as well as the demand for reliable and energy efficient de-icing require the development and assessment of novel de-icing concepts. In the context of ice protection system, the reliable detection of the accreted ice on the wing surface is a key component for both safety and efficiency. On the one hand, an ice detection system indicates whether de-icing should be switched on for the iced section of the wing before the ice can affect flight safety, on the other hand a good system may contribute to avoid unnecessary de-icing and thus a waste of energy or damage to the wing.
Ice-detection by remote probes, as used in most common systems is not able to fulfil these requirements sufficiently. More successfully the issues of safety and efficiency can be tackled by optical ice detection sensors, which are integrated directly into the leading edge of the wing at the relevant portions for ice accretion. The approach of the Clean Sky JU project InAIPS is based on such a sensing system.
The overall aim of the project is a novel approach for improved ice detection and automatic assessment of the potential impact of icing on the drag and lift characteristics of the wing. The project topic therefore addresses three main objectives:
1. Development of a system model for the investigation of ice detection and ice protection;
2. Development and refinement of innovative sensing options for ice detection to support active ice protection systems;
3. Aerodynamic modelling to investigate the impact of icing on the flight properties.
Project Results:
The main objective of the project is a system model for ice detection on laminar flow wings and their impact on the aerodynamic characteristics of the aircraft. The approach as well as the main results and achievements towards this goal are described in the following:
General idea of the system model
Current ice detectors are usually located remote from the critical aerodynamic surfaces (such as the wing) and as such can lead to the ice protection system being triggered in an inefficient manner by activating it long before ice actually starts forming on the wing. The detection of ice on the wing surface, especially for new laminar wing concepts that are particularly sensitive to the presence of ice, therefore allows a more efficient use of the IPS by only activating it when it is needed. To overcome the remote location of current ice-detection systems, the approach of the Clean Sky project InAIPS is based on aero-conformal optical ice detection sensors which are integrated directly into the leading edge of the wing at the relevant positions. The sensor signals are then translated to ice thickness and ice type using an algorithm based on an Ensemble-Kalman Filter technique. The sensing technology and the dedicated algorithm were first developed in the EU FP7 project ON-WINGS. The InAIPS objective goes beyond the ON-WINGS approach by using several sensors and integrating them in a system model which combines the information on the ice accretion with aerodynamic simulations. The final model can be used to assess the impact of the icing of a wing section on the general aerodynamic asymmetry of the aircraft for various flight conditions.
Ice detection sensor technology
In the InAIPS project two different types of ice detection sensors were developed. The first type relies on detecting the backscatter and reflected of light from the ice volume using a fibre array geometry. This sensor type was mounted in two positions on the leading edge of the laminar flow wing, one on the stagnation line and the other one on upper surface of the leading. The second type of sensor was a surface-mounted quasi-distributed ice sensor relying on optical losses induced by the presence of ice on the surface of the wing.
The array fibre sensor consists of a central source fibre and three signal fibres on either side and is a further development of the ice sensor originally developed in the ACIDS and ON-WINGS projects. The further development of this technology undertaken in the InAIPS project was the optimization of a similar sensor architecture for the specific needs of this project, namely the detection of very thin ice, which is particularly disruptive to the laminar flow of the wing.
In addition to the array fibre optical sensors, a distributed ice/no ice sensor was installed to indicate the existence of ice behind the erosion shield. The sensor, in this flash format, is a new development and was tested in InAIPS for the first time. It consists of four sensor units, which were integrated in different glass fibres and a light source fibre. The sensor assembly was mounted on the upper surface of the wing inside a groove specially designed to house the sensor.
The distributed ice sensor was an experimental sensor and as such there is still a need for further development. It performed well in the lab experiments, but when located on the wing, it was not possible to position it in a high ice accreting area, without affecting the airflow and consequently it did not reveal its full potential. In fact some ice was accreting and then flaking off, giving a very erratic signal response which was thus inconclusive.
Data acquisition system
The signal data measured by the sensors is collected by a data acquisition system constituted of an optical interface with 24 photodiodes. The signal transfer from the sensors is realized through ST/PC fibre optical connectors. The data are transferred to a host PC and handed to the post-processing software via a USB port.
Ice detection algorithm
The signals from the optical fibres in the sensors collected by the acquisition system are processed by an ice detection algorithm, which translates the signals to thicknesses based on an Ensemble Kalman-Filter (EKF) technique. The underlying algorithm was first developed during the FP7 project ON-WINGS. In the InAIPS project, the algorithm was tested in coincidence for both array sensors. The ice thicknesses measured during the icing wind tunnel tests serve as basis for a look-up-table (LUT), to determine the thickness from the measured intensity and evaluate the corresponding outside air temperature.
Validation of the methodology showed good performance for the determination of the ice thickness. For the evaluation of the ice type and the corresponding outside air temperature it had some shortcomings at glaze ice conditions, i.e. higher temperatures.
The performance of the methodology is to a large extent constrained by the quality of the LUT, which is compiled from the data acquired during the InAIPS wind tunnel tests. By performing tests for the same conditions repeatedly and covering a range of temperatures and angles of attack, a good set of data could be obtained. Nevertheless, the parameter space is limited. Independency of such LUTs could be reached by using a physical model of the photon intensity to derive ice parameters from the backscattered intensities. The time frame of the InAIPS project did not allow the development and validation of such a model, but these tasks could be subject to possible follow-up activities.
CFD simulations
The shape of the laminar flow wing was used as input geometry for computational fluid dynamics (CFD) simulations to investigate the lift and drag forces on the aerofoil section. The incompressible, stationary simulations were carried out with a Spalart-Allmaras model that was run with an RANS solver. After first simulations with the ice-free wing geometry, sensitivity tests with generic ice shapes of different size and under different conditions were carried out and analysed. When a first set of measurement data had been obtained during the ice tunnel tests in August 2014, the real ice shapes were digitized and their geometry was meshed. The geometries were used to carry out CFD simulations for the iced wing section under the same conditions as for the ice tunnel measurements. By visual inspection and by analysis of the section lift and drag coefficients, the influence of the icing on the flow characteristics under different angles of attack, temperatures, and ice shapes was investigated.
System model
Based on the developments on the sensor, the ice detection model and the CFD simulation, the system model was constituted from the pieces described before.
The functionality of the model can be summarized as follows: The raw data from the optical sensors is fed to the EKF algorithm which translates the intensities to ice thicknesses and evaluates ice type and outside air temperature based on the progress of the intensity signal with ice growth.
From the ice thicknesses detected by both sensors, other parameters can be derived. Factors including the icing conditions and the wing’s angle of attack cause ice to accrete unevenly around the wing’s leading edge, i.e. for a positive angle of attack, more ice accretes on the lower edge of the wing, and vice versa. Therefore, the thickness ratio (TR) of the forward looking sensor and the upward looking sensor is a good indicator for the angle of attack and gives a best guess for the shape of the ice. Although there is a clear relationship between the angle of attack and the accreted ice shape for the InAIPS aerofoil profile, this is not necessarily true for all aerofoils.
Based on the ratio of the thicknesses measured by the setup of the optical sensors, the ice shape is determined and the corresponding CFD simulation determines the lift and drag on the aerofoil.
The final system model should give an estimate of the ice layer’s current influence on the aircraft’s aerodynamic behaviour. Therefore, a linear shrinking algorithm has been applied to calculate ice profiles of different thickness from the original shapes. These are used to perform ice thickness dependent CFD simulations on characteristic shapes from the icing tunnel tests. The results of these CFD simulations are the lift and drag coefficients of the iced airfoil section for different ice thicknesses.
The results have shown strong dependencies of lift and drag on the ice thickness. Even for a thin layer of ice the effect can be immense. The decrease of the lift and increase of the drag is particularly large for climb flight conditions.
The model was finally extended to the assessment of the aircraft’s wing asymmetry due to icing. Ice accreted on an aircraft’s wing can have a strong influence on the aircraft’s aerodynamics. A strong asymmetric behavior can even render the aircraft difficult to control. Therefore, based on the information on the ice thickness, one can assess the force asymmetry and therewith the rolling and yawing moments on the aircraft, which is described in the following. These considerations are used to estimate the discussed quantities in the Matlab/Simulink tool (see next section).
Graphical User Interface
An existing Matlab/Simulink tool for system model testing has been further advanced for the purposes in InAIPS. The user has the possibility to indicate the iced section on the aircraft and the GUI shows the total calculated lift and drag for the aircraft and also indicates the change with respect to the ice free lift and drag in percent. The system further calculates the resulting rolling and yawing moment. The lower left panel visualises the behaviour of the de-icing heater system. The lower right panel shows the control variables.
The evaluation of the total lift and drag forces on the wing as well as the rolling and yawing moments allows to assess how critical the icing of a wing section is for the flight characteristics of the laminar flow wing, or, in the context of an Ice Protection System (IPS), how critical the failure of a certain de-icing section would be. The system model is thus a useful tool to investigate the number of independent de-icing zones needed to ensure flight safety even in the case of partial failure of one or more zones
Potential Impact:
Summary of the dissemination activities
The InAIPS project team has successfully developed a system model for the aero-conformal detection of ice on a laminar wing surface and its impact on the flow characteristics. The sensing technology developed in the predecessor EU FP7 project ON-WINGS was further developed and improved, in particular for the detection of thin ice layers.
The project partners have undertaken different activities for dissemination of the project results. The ice detection technology integrated in the wing model was exhibited together with a live demonstration of its functionality on the Airtec fair 2014 in Frankfurt a.M. Germany. At the same place, an oral presentation on the preliminary results of the project was given by TWT at the corresponding Airtec conference.
The consortium futher proposed the project to the Clean Sky office for exhibition and presentation at the upcoming Aerodays in autumn 2015.
These dissemination activities strongly contribute to promote the technology and catch a wider audience’s interest in the InAIPS results.
Impact of the InAIPS results
The project InAIPS will create a strong impact on the European Aircraft sector, by addressing de-icing capabilities as an important safety-critical aspect of aircrafts in the context of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator. Focusing on the overall aim of a novel approach for improved ice detection and automatic assessment of the potential impact of icing on the drag and lift characteristics of the wing in all flight phases, the project results will have an impact on important aspects in the ACARE and CleanSky objectives. The semi-empirical system model developed in InAIPS represents an efficient methodology to approach the challenges.
Since a reliable ice detection method as advanced in InAIPS tackles the issue of energy and fuel burning efficiency from the beginning on, the project contributes on building up a strong European position for the given challenges of exploiting the green aviation domain. Building on comprehensive sensing and modelling the project results are an important step towards a closed loop approach for aircraft ice protection and thus contributes to strengthen the European leadership in cross-cutting technologies. The integrated use of advanced modelling techniques in the aeronautical domain moreover will leverage the overall application of digital design towards more and effective solutions in the frame of optimising air transport.
Addressing the overall mission of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator, the activity will derive a beneficial combination of techniques for reaching the overall SFWA goals. The straight-forward approach of InAIPS supports high-quality ice protection systems for also illuminating the energy aspects within scope of reducing the energy footprint.
In addition to helping to achieve CSJUs overall SFWA targets, this activity will strengthen the position of European Aircraft development in an ever more competitive world market. As Europe is among the leaders in striving for CO2 emission reduction and cleaner transport, this competitive advantage will become even more beneficial when other markets turn their gaze upon Green Aviation.
To summarize, in the InAIPS project, essential aspects for a full deployment of novel wing architecture in the context of the Smart Fixed Wing Aircraft Integrated Technology Demonstrator are investigated. The project results set the stage for the following array of impacts.
• The development of the InAIPS system model builds a comprehensive basis for assessing and optimizing the performance of ice protection systems addressing flight safety and energy awareness.
• The sensing technologies developed and refined in InAIPS represent an accurate and reliable system for ice detection and thus provide an important contribution to safer aircraft configurations.
• Due to the development of innovative sensing options to support the active ice protection strategy, an important aspect for intelligent systems in the aviation domain is addressed. The concept of supervision and sensing can then be enhanced for other aspects within the aircraft, e.g. cabin air-conditioning, using different sensors.
Hence, the project results contribute to building towards a strong European case for the upcoming challenges of exploiting the aviation domain. They bring added dimensions of flight testing capability and sensor technology and contribute to the overall reduction of fuel consumption and CO2 emissions.
