Wind turbine blade Anti / De-icing, combined Ultrasonic guided wave and vibration system

Final Report Summary - DEICE-UT (Wind turbine blade Anti / De-icing, combined Ultrasonic guided wave and vibration system)

Executive Summary:
Wind energy is currently the fastest growing renewable energy source in the world and therefore attention has to be given to their wellbeing. By their nature, wind turbines are placed in exposed positions and snow and ice is always a threat in colder climates. The build-up of ice on a turbine blade will affect its performance and may lead to damage and even catastrophic failure. Ideally, the accumulation of ice should be stopped at the moment of creation. To overcome this problem, the DeICE-UT system operates in two modes; anti-icing and de-icing.

Existing passive solutions to the ice build-up problem include; special coatings applied to the surface of the wind turbine blade to reduce the adhesive properties of the ice, painting the turbine blade black to enhance solar heating and applying chemicals to the surface to lower the freezing point of water. None of these is entirely satisfactory. Coatings are not totally effective in hindering ice formation; the solar heating effect only works in bright sunny conditions and chemical applications are problematic at height and are pollutants.

The most common active solution is to create a thin film of water under the ice with thin-foil electrical resistors embedded in the blade. This process can consume 12% of the turbine’s nominal power output. Another active solution is to circulate hot-air within the blade, but GRP blade material is a thermal insulator and to melt the ice may consume as much as 15% of turbine output. Pulse Electro-thermal De-Icing is another active solution that claims to use less power by sending pulses of current through the heating elements, but there are no commercially available systems. Finally, the Electro Expulsive Separation System de-icing device passes currents through wires glued on to the surface of a blade causing them to interact electromagnetically, creating slight movements that shake off the ice. The manufacturers claim very low power consumption, but the system has only been tested on the leading edges of small aircraft blades. Active Pitching is a solution that doesn’t need an external device or supply. It relies on rotating the blades through their centreline axis to a point when the leading edge of the blade faces the airflow beyond a certain angle, causing turbulent flow and forces that shake off the ice. Of course, there is a risk of damage to the blade.

The DeICE-UT project aim was to overcome the limitations relating to the Anti-icing/De-icing of wind turbine blades by integrating two technologies which use low cost components that require relatively low energy and have the potential to achieve both anti-icing and de-icing at temperatures down to -20°C. The two technologies are Low Frequency Vibration and Guided Wave Ultrasonics. The DeICE-UT project sought to build on previous research and the initial investigations of the SME consortium. The project has nine partners from six EU member states, including five SMEs. The SMEs include high technology organisations manufacturing composite parts (Floteks), high power ultrasonic transducers (Smart Materials) and electronic amplifiers and instruments (BS-Rotor and DTK). In addition, Tureb, as a large enterprise that provides customer support to the world's infrastructure markets in the fields of power generation will act as the initial route to market. The project is supported by three Research organisations; Brunel University (UK), which is providing expertise in numerical modelling, West Pomeranian Technical University (Poland), which is providing expertise in hardware for arduous conditions and TWI (UK), which will be developing the techniques and acting as project coordinator.

The two techniques were activated from two sets of transducers placed inside the turbine blade. One set is placed centrally along the blade at distances calculated to give maximum vibration. Another set was in the form of an array that propagates guided ultrasonic waves around the leading edge of the blade. The technical objectives were to optimise two these techniques to prevent ice formation and remove ice.

Project Context and Objectives:
WP1: End-user requirements and hardware specifications
In this work package, a functional specification for the prototype system based on a survey of end-user requirements has been drawn up, from which specific technical specifications for system components are written as the techniques are developed. A sample section of wind turbine and a mock-up wind turbine blade were acquired and a venue for the final system trials has been agreed at one of MIRA’s vehicle environmental testing chambers.

WP2: Theoretical study and modelling
This work package has been divided into three tasks. In the first, guided wave propagation around the skin of the turbine blade has been investigated and the optimum conditions for breaking the adhesion between the accreted ice and the substrate. The Interface Stress Concentration Coefficient (ISCC) parameter for a range of ice thickness accumulations has identified for guided wave modes in the so-called dispersion curves that plot their phase velocity against frequency. In the second task, low frequency vibrations that excite resonance modes in the turbine blade have been investigated. The displacement, acceleration and stress responses of the blade to a range of resonating modes were used to identify optimum shaker frequencies and placements along the blade. In the final task, the effect of these resonating modes on the fatigue life of the blade was investigated, to ensure they did not cause a problem. All shaker arrays were found to generate stresses well within the tolerable loading cycles that literature have proposed for composite wind turbine blades.

WP3: Ultrasonic transducer and vibration shaker
Both ultrasonic transducer and vibration shaker were investigated. The original work programme had proposed the use of commercially available off-the-shelf high powered (HP) transducers incorporating acoustic wedges to propagate guided waves. These HP transducers are used in ultrasound cleaners and plastic welders and an inexpensive source was identified and transducers acquired for the GUW technique and low temperature pulser-receiver (WP4) development. For the technique development the use of wedges to propagate specific wave modes was investigated both experimentally and with numerical models and the relationship between wedge angle and phase velocity established. The data from the experiments and from the models were then used to construct dispersion curves to match those used in WP2. The wedge angle and transducer frequency could then be selected to generate the specified ISCC. However, it was found that the HP transducers mounted on wedges could only propagate guided waves with out-of-plane displacement (longitudinal), whereas WP2 identified guided waves with in-plane displacement (shear) as the most effective at breaking the ice adhesion. The work programme has therefore been revised to use arrays of shear transducers. These are not available commercially.

Two shaker systems have been studied and evaluated; shaker with an eccentric mass imbalance and shaker with an eccentric mass balanced in the mid plane. Trials have been carried out on both systems while measuring the acceleration and stain at certain points on the blade. In terms of measurements and control the shaker with the eccentric mass balanced in the mid plane was used for the final trials.

WP4: Low Temperature pulser receiver and shaker
A low temperature pulser-receiver for the commercially available HP transducers has been developed during the project. A limit of -20°C had been set to avoid having to use very expensive electronic components in the prototype. HP transducers rely on a resonance to maximise their output and a novel way of controlling this according to the transducer’s loading has been developed. The pulser-receiver needs to be modified to operate with arrays of shear transducers.

A market survey of existing shaker control units was undertaken. However, in order to fulfil technical requirements, a prototype of vibration shaker unit was designed with cutting edge components to achieve necessity reliability for the devices working under winter climate sites around the world.
All goals of this task, designing and constructing a prototype of shaker, as well as power and control units that are controlled within a certain range of frequencies and amplitudes, were successfully achieved. A supply control system comprise of a printed circuit board placed in one chassis with circuit board designed for SH-waves. Controlling the rotational speed of the motor allows control the output vibration frequency, whilst changing the radial location of the mass allows control the amplitude of the vibration. Developed software allows for co-working SH-waves and Shaker suppliers systems. Special modes for testing and continuous work were implemented in the software.

WP5: DeICE-UT Integration
After a detailed market research partners decided to use Labkotec Oy LID-3300IP Ice Detector for Wind Turbines and Meteorological Stations as the system made in order to use with wind farm. What is more, such system apart from relay ice alarm system may also deliver much more useful 4-20mA current signal, which may be used to design more sophisticated system.

The low temperature pulser-receiver unit and shaker power and control unit was successfully integrate into one system. Laboratory testing trials were successfully carried out at ambient temperature to access the system performance prior to the wind tunnel trials.

WP6: DeICE-UT system demonstration
The DeICE-UT system was mounted on to composite test pieces. The low power ultrasonic transducers were attached to a section of a full scale wind turbine blade whereas the shaker system was installed on to a 4.5m long mock-up composite wind turbine blade for the wind tunnel trials.

The system demonstration was carried out at MIRA’s vehicle environmental testing chambers. The system was prepared to be suitable for the low temperature tests. Different types of ice were formed on the two test pieces. Accelerometers and strain gauges were used to measure the system performance and behaviour. It was concluded that SH waves to use anti icing and to soften the ice and then the shaker to shake the ice off.

WP7: Results Dissemination and exploitation activities
As part of this work, a project website has been created and a draft plan for use and dissemination of
Foreground has been written.
Dissemination activities have been carried out by the partners in different regions. They include international Wind Power Congress in Istanbul-Turkey- IWPC 2015, JEC Europe 2015- France, The Regional Centre for Innovation and Technology Transfer event-Poland, SAE 2015 International Conference-Czech Republic. The work has been published in Renewable Energy journal.
The project video has been developed and uploaded to the project website.

WP8: Management and coordination
Work Package 8 refers to Project Management and Coordination, which has been an on-going task throughout the project duration. This work package also includes Project Management of Technical and Administrative activities and all Project Reports (Progress Reports, Technical Reports, WP Reports, and Final Project Report). As part of this Work Package the Project Coordinator planned, organized and monitored the project for administrative, legal and contractual matters, quality and standards representation and implementation. Allocated budgets & cost statements were collated and reviewed prior to submission to the EC. The Project Manager planned, organized and reviewed at six month intervals the technology, product and knowledge management work packages with the Work Package Leaders. Also the Project Manager dealt with the day to day inter-participant or consortium level issues.

Project Results:
WP1: System Specifications
Partners involved: TWI, BSR, DTK, SelfTech, Tureb, Floteks, SMG, ZUT, UBrun
System Specifications and selected wind tunnel
1. Overview
This work package was decided on the supervisory hardware used in the system, as well as taking into account the end users requirements in order to select the most appropriate test conditions (wind tunnel).

2. System Requirements
An overall electronic power supply system specification is given. Due to project proposals, a maximum power density of 1W/cm2 was considered, regarding the active area of 1m2 (test turbine blade) resulting in the maximum power of 10kW.

In both cases (ultrasound and shaker system) a modular approach is proposed resulting in 5 x 1kW (or alternatively 4 x 1250W) ultrasound sources and 4 x 1250W shakers. Shaker numbers is only an estimation and needs to be verified.

In the case of ultrasound systems, high voltage pulse generators are proposed (in modified Marx or Fitch topologies), in case of shakers 4Q bridge inverters are suggested. Both supply systems should contain a DSP based control unit with standardized, industrial communication protocols (CAN protocol for example).

Both systems will be referred to separately, as their operation is fundamentally different.

Ultrasound power electronic supply system should exhibit following, main properties:
• High efficiency,
• Controllable pulse amplitude (power) and repetition frequency,
• Modular construction,
• System synchronization and data interchange.

Shaker-based system should exhibit following properties:
• High efficiency,
• Controllable shaker power and excitation current frequency,
• Modular construction,
• System synchronization and data interchange.

WP2: Theoretical study and modelling
Partners involved: Tureb, UBrun
Modelling of guided waves and vibration in the blade
1. Overview
This work package was focusing on mostly theoretical work mainly with modelling and optimisation tasks.

2. Ultrasonic Array Topology for maximum energy concentration on the leading edge of the wind turbine
The approach for modelling was as follows:
(1) Sample preparation;
(2) Structural solid module, eigenfrequency function in COMSOL for dispersion curve analysis and ISCC analysis;
(3) Stress and displacement distribution with selected wave mode and frequency for de-icing.

Aluminium plate, glass fibre composite plate and a composite blade were selected as the samples, with varied thicknesses of ice.

Dispersion curves and ISCC coefficients were calculated for plate and actual blade made from either metal or composite for the selection of wave mode and central frequency. Table 4 in deliverable D2.2 summarises the optimised central frequency, phase velocity and wave length of ultrasonic waves according to different situations including material and thickness of ice. These outcomes provide guidance of the selection of frequency and wave mode for the design of transducer arrays.

This study was followed by an investigation of allocated transducer arrays to focus energy. For the aluminium plate, a 2 by 2 transducer array was implemented. The distance for each column and row was (4+1/2)λ and ¼ λ respectively. The ultrasonic wave was guided and the power concentrated on the line x=0 (central vertical line) of the sample as might be expected. For a GFRP plate or blade, the ultrasonic waves are easier to propagate along the fibre orientation because of the anisotropy in material properties. Therefore, a pair of transducers in fibre orientation could be used to focus power and guide the wave instead of a 4 transducer array. Results show that the ultrasonic wave was guided and power concentrated on the central vertical line of the plate and the leading edge of the blade respectively. It was concluded that this approach appears effective for guiding ultrasound and concentrating power.

3. Vibrators placement for optimal leading edge translation
A FEM model of wind turbine blade was built to investigate the structural responses of blade to forced vibration induced by vibrator. The first seven modes, including firstly, three flexural bending modes and torsional mode, were calculated from modal analysis. The resonant frequencies of blade were determined, as summarized. The corresponding modal shapes of blade are plotted in Fig. 4.4 in deliverable D2.2.

Vibrator loading scenarios for different placements of vibrators were investigated. Optimum topology of vibrators was studied based on the comparative results from harmonic analysis. The structural response of the blade to harmonic excitation created by vibrators, including displacement, acceleration and von Mises stress were calculated. Different topologies of vibrator placements, including seven loading cases consisting of single, double and triple vibrators, were considered. For each loading case, frequency response of blade in the frequency range [0 50] Hz were calculated from harmonic analysis. Table 6.1-7 in deliverable D2.2 summarizes the peak displacement and acceleration amplitudes obtained from harmonic analysis for loading case 1-7. Table 6.8 in deliverable D2.2 summarizes the peak amplitudes of von Mises stress from harmonic analysis for loading case 1-7.

It can be concluded that the optimum topology of vibrators is the three-vibrators set up, ie loading case seven. This case generates the largest displacement and acceleration at each point. If single or double vibrators are adopted, by comparison of results as shown in Table 6.1-6.6 in deliverable D2.2 it is more effective to place the vibrator near to the blade tip rather than the blade root to induce larger acceleration responses.

It should be noted that the largest displacement and stress were usually created at the first natural frequency, i.e. the first flexural bending mode, while the largest acceleration was found to be at a higher mode, in this case at around 24-25 Hz. A higher frequency forced vibration of blade can give larger acceleration but also largely decrease stress, thus significantly increasing blade fatigue life.

4. The effects of vibration on the fatigue performance and dynamics of the blades
In the project, a study for predicting the fatigue life of a wind turbine blade was performed. First a FE blade model using ANSYS® 14 was developed. Then the dynamical behaviour of the created model was verified through comparing mode shapes and natural frequencies with another work. The dynamic performance of the blade model was sufficiently consistent especially in the first modes that dominate the dynamics of the system. Likewise the best potential points for mounting shakers were proposed through modal analysis and superposing mode shapes and their nodes. Deliverable 2.2 contains further explanation on the optimum shaker array. This is important as it characterized what points (shaker arrays) and directions (x and y) the blade should be excited at.

In the next step, performing a FE stress analysis over a 30-Hz frequency range showed that the first mode is the critical one as it undergoes much higher stress than the other modes. 33.

This mode causes the most risky situation and it is therefore the most likely mode under which failure could happen. The fatigue approach presented by Eq. (2) in deliverable D2.3 corresponds to the first mode of the blade subject to a varying load which made it suitable for the current study.

The fatigue analysis showed that almost all shaker arrays comply with standards of composite blades regarding fatigue life. In other words, they all lead to the tolerable loading cycles that literature has proposed for composite wind turbine blades. Note that determining a certain number of cycles for fatigue life depends on what array and positioning of shakers is finally chosen to maximize the achievement of ice removal. This issue has been discussed and reported more extensively in Deliverable D2.2. Here, the results provided give the good news, based on the data in Table 4, that none of the scenarios will lead to a significant reduction of life. Furthermore, the fatigue life will be significantly higher if the blade should be excited at any frequency other than the first natural frequency. Vibrating the blade at higher modes might be applied if larger acceleration could be generated there (see Deliverable 2.2).

Another observation is that the magnitude of the applied harmonic force is not a crucial factor because it is closely associated with the damping ratio of the force. As an example, it was shown that effects of a 100 N force with no damping is roughly equal to a 500-N force of =0.1. Accordingly, if needed, a range of acceptable sets of force amplitude-damping ratio could be easily determined which would lead to an approximately similar operating acceleration and fatigue life.

WP3: Ultrasonic transducer and vibration shaker
Partners TWI, BSR, , Tureb, Floteks, SMG
High power ultrasonic transducer optimisation and Wind turbine blade shaker development
1. Overview
This work package the active elements of the DeICE-UT system was developed.

2. High power ultrasonic transducer optimisation
It was decided that actuators would be mounted on the specially prepared aluminium shield and not directly onto the composite. For each shield, four identical actuators were selected. The actuators were of piezo electric shear stack type (Model NAC2403-H3.4 supplied by Noliac). These are 10x10x3.4mm with an unloaded resonant frequency of 137.5KHz and a peak displacement of 6μm at 300V.

During pre-trials, actuators were mounted using the clamps. However it was found that the clamps had little effect on the resonances of the actuator and they could be bonded effectively to the surface using Loctite superglue. Indeed the glued actuators gave a noticeably higher output.

Actuators were mounted on an aluminium shield. Two types of the shield were selected for trials. One type was a flat plate and the second one a curved plate to fit over the leading edge of the blade. The width of the plate is critical to creation of SH-wave resonances in the plate. The actuators must be aligned so that the shear motion is across the plate and the SH-wave propagation is therefore along the plate. For the first order resonance mode, the width of the plate must be equal to half the wavelength of the S0 waves propagating in that direction. At 27.5KHz the phase velocity of S0 waves is 5550m/s in Aluminium, giving a wavelength of 200mm. For first order resonance, the plate width therefore must be 100mm.

To enhance the SH-waves propagating along the length of the plate, the actuators must be placed so that the SH-waves from each actuator are interfering constructively. This can be done by placing them one wavelength apart, when they are powered synchronously. The phase velocity of SH waves is constant at any frequency ie non-dispersive. In Aluminium, the phase velocity is 3130m/s, so at 27.5KHz the wavelength is 112mm. By placing the actuator ¼ wavelength from the end of the plate, constructive interference with the SH-wave travelling in that direction also occurs.

3. Wind turbine blade shaker development
In this task, a study to construct a vibration shaker using rotating eccentric weight was performed. Firstly, the verification of this type of excitation was validated using a FEM model of prototype blade. Simulations have been performed using the commercial software SolidWorks. Modal and harmonic simulations on a blade have confirmed that the de-ice of blade can be archived using this type of excitation. The stress level needed to break the ice are reached and even exceeded assuming an eccentric weight specifically calculated for this blade, 0.16kg of mass and 0.06 m for the radius in the range of 0 to 50 Hz. It is concluded that the weight of eccentric and its radius position need to be estimated carefully for each specific structure.
The validation of the vibration shaker using the rotating eccentric mass is accomplished in section 4 of this document. From the results presented it is possible to conclude that the control of the rotational speed of the motor is correctly controlled with a variable-frequency drive (VFD) and RMS amplitude of acceleration demonstrate the expected result for the eccentric weight.
The force has been estimated with regards to the mass, the radius (related with amplitude) and the specific system of fixation in motor is explained and demonstrated for a specific eccentric weight of 0.4kg and a radius of 0.15m.
Finally, it was proposed to use alternative solution and improvements for the progress of this work, such that the development of linear harmonic excitation using the same concept of the rotating eccentric weight. And a shaker with eccentric mass balanced in the mid plane was used for the final trials.

WP4: Low Temperature pulser receiver and shaker
Partners involved: TWI, ZUT, DTK, Tureb, Floteks
Low temperature pulser-receiver unit development and Shaker, power and control unit development

1. Overview
In this Work Package a low temperature pulser-receiver system and a dedicated shaker control unit for the DeICE-UT system was developed.

2. Low temperature pulser-receiver unit development
The ultrasonic pulser-receiver unit task T4.1 was defined regarding the development of the unit. Both the power electronic half-bridge design and prototype controller construction were provided with laboratory test-stand verification of operation. A change was made regarding the initially proposed high-voltage pulsed supply due to controllability and output power characteristics of a high-power ultrasonic transducer. Finally a square – wave supply is proposed with output low pass filter as a compromise between controllability and complexity. Digital signal processor unit was developed for individual resonance point tracking of each device. Test stand results are given to verify proper prototype operation.

In case of the shaker unit the target T4.2 – power and control unit development was also partly achieved. An industry – standard shaker was purchased and tested in simulated conditions in a preliminary way. Frequency and output power control was experimentally validated.

3. Shaker, power and control unit development
A market survey of existing shaker control units was undertaken. However, in order to fulfil technical requirements, a prototype of vibration shaker unit was designed with cutting edge components to achieve necessity reliability for the devices working under winter climate sites around the world.

All goals of this task, designing and constructing a prototype of shaker, as well as power and control units that is controlled within a certain range of frequencies and amplitudes, were successfully achieved. Supply control system comprise of printed circuit board placed in one chassis with circuit board designed for SH waves. Controlling the rotational speed of the motor allows control the output vibration frequency, whilst changing the radial location of the mass allows control the amplitude of the vibration. Developed software allows for co-working SH-waves and Shaker suppliers systems. Special modes for testing and continuous work were implemented in the software.

WP5: DeICE-UT Integration
Partners involved: TWI, BSR, SelfTech, Tureb, Floteks, ZUT, UBrun
DeICE-UT system integration and Laboratory testing

1. Overview
In this Work Package the DeICE-UT system was integrated and laboratory tests were performed to evaluate the system performance in ambient temperature prior to the wind tunnel trials.

2. DeICE-UT system integration
After a detailed market search the project partners decided to use Labkotec Oy LID-3300IP Ice Detector for Wind Turbines and Meteorological Stations as the system made in order to use with wind farms. Such systems, apart from relay ice alarm system, may also deliver much more useful 4-20mA current signal, which may be used to design a more sophisticated system. To sufficiently detect ice formation Labkotec Oy LID 3300IP Ice Detector for Wind Turbines and Meteorological Stations was integrated into the DeICE-UT system. This system allows for detecting ice formed on dedicated standalone sensor. The sensor needs heating in case of leading another ice detection process. Hence, the sensor was connected via two delivered by producer wires (signal and heat suppling) with the main brick of the system.

For the ultrasonic guided waves, it was decided that actuators would be mounted on the specially prepared aluminium shield and not directly onto the composite. For each shield, four identical actuators were selected. The actuators were of piezo-electric shear stack type (Model NAC2403-H3.4 supplied by Noliac). These are 10x10x3.4mm with an unloaded resonant frequency of 137.5KHz and a peak displacement of 6μm at 300V. Electrical connections were made to supply SH-wave actuators. Each actuator has two-wired AC connections. For each pair of four actuators, the suitable interface on the front of supply system was installed. In order to assure adequate power performance, each actuator is supplied via a separated channel. A more detailed description regarding the supply system is reported in deliverables 4.1/4.2. The interface of the supply system is presented on the Figure 9 (deliverable D5.1).

At the initial stage, an electric motor with the similar specifications of the final shaker was tested to excite the blade at resonant frequencies. In the laboratory trials with the electric motor, this was mounted at the widest part of the blade (Figure 10 in deliverable D5.1). This was based on the modelling work carried out in WP2 and WP3 and to validate the proposed eccentric weight type of excitation.

At the second stage and now using the adopted shaker for the final trials (report in Deliverable 4.2) the shaker was installed inside the blade. As presented in Figure 11 in deliverable D5.1 the shaker was placed at the blade root, the only location founded in the proposed prototype blade with enough space to allocate this large component. Due the very flexible characteristics of the structure used to support the blade on the horizontal plane, it will be expected that the excitation loads created by the rotating eccentric weight will be transmitted through the blade structure. However, in the vertical plane and with the same shaker position, very lower excitations will be expected due to the constraint imposed by the floor on the support, resulting in very small vertical amplitude of vibrations. The validation for this integration will be presented in future reports. The shaker was inserted into a nylon tube to fix to the blade and using an expandable system this was fitted perfectly to the internal diameter of the blade root. This very easy but efficient system of fixation demonstrating a perfect fit with the blade root made the shaker solidary to the blade. The power and control unit presented in Deliverable 4.2 was integrated to supply the shaker system. As previously mentioned, this unit supplies the shaker with a desired voltage frequency proportional to the angular velocity of the shaker. To specify the desired parameters, fully developed software is available and installed in a normal PC.

3. Laboratory testing
This task a series of laboratory tests carried out through cost-effective, procurable lab facilities to evaluate the performance of the ice protection system for a wind turbine blade before wind tunnel trials. The tests can be summarised in two distinct sections; Low-frequency vibrations and Ultrasonic guided waves.

In terms of the tests corresponding to vibrations using shear strain gauges on the blade, the results turned out to be consistent with modelling results in which the frequency of 25 Hz created the highest shear strain due to generation of sufficient acceleration at this mode. In other words, the frequency range in which ice removal is of the highest chance to be achieved was identified. However, since the shaker setup in the lab, due to some restrictions associated with the procured blade, is different to the modelling conclusions, a concern remaining is that the expected mode shapes would not be generated.

Likewise the processed data obtained through OMA provides a good understanding of the dynamical behaviour of this structure. Also, the first two flexural bending modes in flapwise, the third general mode and their corresponding peak accelerations and displacement were identified.

As for the work on UGW, the conclusions can be listed as the following,
• SH waves are attenuated too strongly in GFRP for them to be used to de-ice the leading edge of a wind turbine blade and therefore an innovative solution has been proposed, where an Aluminium strip is inserted along the leading edge, to which the SH-wave actuators are attached.
• The highest power SH-waves are attained when the strip resonates. SH0 waves should propagate along the length of the strip with the orthogonal S0 wave at first order resonance across the strip. The most important influencing parameter is therefore the strip width, which should be selected to give resonance at the required SH wave frequency.
• For the prototype UGW de-icing system, it is proposed that the Aluminium strip for leading edge, scaled down for use on the mock-up, is made 100mm wide, and 392mm long with the 4 actuators placed along its centre-line.
WP6: DeICE-UT system demonstration
Partners involved: TWI, BSR, DTK, SelfTech, Tureb, Floteks, SMG, ZUT, UBrun
Sample and system preparation and Wind tunnel trials

1. Overview
In this Work Package the composite test samples were prepared for the wind tunnel trials according to the requirement of the end user, Tureb. The systems were integrated on to the composite pieces and the trails were carried out in a wind tunnel at MIRA.

2. Sample and system preparation
In order to demonstrate the DeICE-UT technologies two types of test pieces were prepared; a section of a full scale wind turbine blade and a small scale mock-up wind turbine blade. The section of the full scale turbine blade only a small part of this was cut out. The objective was to consider only this small cut containing the leading edge is to mounting the developed SH actuated aluminium shield described on Deliverable 5.1. In order to integrate the low frequency shaker technology the small scale mock-up wind turbine blade was used as reports such the Deliverable 5.1.

The final tests are focused on demonstrate two different technologies the guided wave US technologies and the low frequency vibration applied to the leading edge of the blade section and the small scale mock-up wind turbine blade, respectively. Both of these specimens were sent to MIRA facilities to be installed and prepared for the climatic chamber tests.

The integration and predation of DEICE-UT system was carried out according to the following procedure:
• Installation of the small scale mock-up wind turbine blade on the metallic support;
• Application of a protecting coating over the strain gauge;
• Shaker installation on the root of the blade;
• Installation of two accelerometers on the root of the blade to vibrations monitoring;
• Aluminium shield with the US actuator installation on the leading edge of section blade;
• Installation of DEICE-UT control unit, strain monitoring system and wire connections;
• Construction of a water proof protecting box for the electronic systems;
• Ice detection system installation;
• DEICE-UT Labtop system control installation and auxiliary equipment to parameters monitoring.
3. Wind tunnel trials
In this task the main goal was to simulate in wind tunnel the conditions which may cause the occurrence on the blade various types of icing and to valid Anti/De-icing system. No rotating parts were utilized in this work. Thus the system passed the trials for its anti/de – icing capabilities in the closest conditions to the true ones. The effects on the blade performance in terms of fatigue or dynamic performance were determined. The whole process of the wind tunnel trials was filmed so as to create an excellent press kit. The entire project consortium was responsible for this task.

The trials allowed validation of the designed and built devices as well as general assumptions about the anti/de-icing methods. The supply system manages to operate in low temperatures (less then -200C) and deliver the requested supply signals parameters (frequency and voltage). Due to the manual ice formation method validation of the system for wide range of ice types was limited. For formed ice types (rime and snowflakes) de-icing (shaker) system turned out to be effective in case of dropping rime type of ice. What is more, the system allowed meanly breaking the ice more than shaking it off. On the other hand, anti-icing system (ultrasound) proved its comparative efficiency. The ice formed on the shield with operating transducers was characterized by weaker adherence ice to the shield. Hence, it is proposed using combined anti and de-icing system to achieve expected results.

WP7: Results Dissemination and exploitation activities
Partners involved: TWI, BSR, DTK, SelfTech, Tureb, Floteks, SMG, ZUT, UBrun
Results Dissemination and exploitation activities

1. Website

As part of the DeICE-UT Project, TWI hosts a website on behalf of the consortium with the domain name http://www.deice-ut.eu/.

The website consists of the following tabs:
• Home: Title and summary of the DeICE-UT Project. The latest news on the project can also be found in the home page.
• Project: This has three sub-tabs; project overview, project concept and project objectives. The project objectives have been presented in terms of scientific, technological and operational.
• Project partners: a brief description of each of the DeICE-UT project partner is included in this tab. The description, web-link and the logo of each company has also been incorporated.
• Publications: This tab includes more details on project content and objectives, the proposed solution and work packages.
• News & Events: A very important part of the DeICE-UT project is the dissemination activities and events. In this tab, all the conferences and events where information on DeICE-UT project is published and disseminated by the project partners are presented.
• Contact us: contact details for Project Coordinator, Graham Edwards, TWI Limited.
• Private Area: secure member area to upload deliverables, meeting minutes and other documents for the project partners.

2. Promotional videos
As part of the DeICE-UT Project, TWI developed promotional video in collaboration with the DeICE-UT project partners.

This video was developed in parallel by the RTD’s and TWI as coordinator formatted and merged the different clips into a video.

Additionally, the promotional video was published in the DeICE-UT Website for public access and dissemination of project results.

The different tasks carried out in order to develop the video are described as follows:
• Recording and clips explaining the two technological developments.
• Recording and clips explaining system configuration.
• Recording and clips explaining system operation.
• Recording of laboratory trials
• Recording of wind tunnel trials
• Integration and formatting of videos into a common style.
• Development and synchronization of speech text to be embedded in the video.

This video complements other dissemination materials produced by the DeICE-UT consortium as well as banners and posters and are being used for project dissemination.

3. Draft Plan for Use of Dissemination of Foreground
A Plan for Use and Dissemination of Foreground (PUDF) was carried out as set out in the Description of Work for the DeICE-UT project. The interim PUDF has been reviewed and amended during the course of the project as directed by the Project Steering Committee (PSC) and implemented by the Exploitation Manager, Mr Jeremy Sheppard from BS-ROTOR, who has been responsible for the planning and coordination of all activities related to adequate and timely dissemination of the project results within the consortium and externally within EU and global NDT and Wind energy community ensuring an appropriate level of disclosure for each action.

The PUDF includes a plan to attract investment for the DeICE-UT technology beyond the duration of the project.

4. Final Plan for Use of Dissemination of Foreground
The PUDF covers management of knowledge and intellectual property and its interrelation with the various innovation-related activities planned. This also includes the management of activities to ensure that the results are adequately protected and that the dissemination is carried out without threatening the partners’ ability to protect the knowledge. After the project, the PUDF will be developed into a working business plan, with a policy to protect the IPR developed in the course of the project. The Exploitation Manager; Jeremy Sheppard of BS-Rotor will continue to coordinate the partners as well as external agencies and bodies engaged in the innovation-related activities even after the official completion of the project.

The PUDF is aimed at the following audiences and respectively at the fulfilment of the following objectives:

• European Commission: to communicate the consortium´s strategy and report on dissemination activities.
• Consortium partners: to inform about participants ´rights and obligations, as well as notify to other participants partners´ intentions in order to enable them to exercise their objection right in case their legitimate interest could be impaired.

The consortium has looked into the full spectrum of exploitation opportunities of the project results and not just the product development. Therefore, it is intended that exploitable results in the project will arise in many forms. Apart from the technologies developed within the project which will form the basis for commercial products and protected through patents and IPR agreements, exploitation opportunities include: Input to standardization activities, know-how into further EU-sponsored projects, know how into national and industry-sponsored research projects, development of new services based on the prototypes, methods and tools developed by the consortium and finally, the creation of start-up businesses to commercialize the results.

The DeICE-UT project partners have recognized from the early stages of this initiative the features that will comprise the proposed systems and the industrial, financial, societal and environmental benefits of its successful implementation as a whole. The role of the industrial partners in the exploitation plan of the project results will be extremely important as they have agreed to proactively pursue the aforementioned exploitation plans. The industrial partners of the consortium will take a leading role in the exploitation of the results since these partners have the greatest commercial experience and play a vital part for the results to reach the appropriate markets. Furthermore, there are no existing anticipated business agreements which may impose limitations on the subsequent exploitation or information or inventions generated as a result of the project.

The Final version of the PUDF is divided into three main areas:
• Intellectual property protection
o The following different types of IP are recognised: Patents; Designs (both registered and unregistered) for the process equipment; and Copyright for the algorithms and process software. Only the participating SMEs; BS-Rotor, DTK, Floteks; SelfTech and SMG have ownership of and exploitation rights to the Foreground IP derived in the project. Any patents applied for are on a joint basis so that no one company will derive unfair advantage in relation to the exploitation rights of the other participants.
• Exploitation of results
o As a part of the DeICE-UT project, the SMEs in the project have established a business alliance that will be on-going post-project and will enable the protection, management and exploitation of the project results. It has been agreed that project partner BS-Rotor will exploit the De-icing Method by providing a service, which will be offered alongside its current wind turbine blade maintenance and inspection services.
o SMG, SelfTech, DTK will design and manufacture their results and supply these to their customers, using the IPR protection secured to exclude other manufacturers. Floteks will develop a new Turbine wave design which includes the de-ice guard and/or the shaker in the blade root. BS-Rotor will provide a service retrofitting the DeICE-UT system to existing wind turbines. Both BS-Rotor and Floteks will look to integrate the specific component technologies and then design, manufacture and install the resultant DeICE-UT solution to relevant end-users.
o The initial route to market for the technologies, designs and services will be through Tureb, a large multi-national company that develops, constructs, markets and provides systems, components and customer support to the world's infrastructure markets in the fields of power generation. Although Tureb will achieve first to market advantage, they will not be offered exclusivity and the SME consortium will achieve sales of the integrated system to other end-users of the technology. The consortium SMEs will benefit from the DeICE-UT project by ownership of IPR giving them an enormous competitive edge.
• Business plan
o This Final PUDF forms the basis of a plan to exploit the project results beyond the end of the project. There are two parts to this. The first is a development plan to take the prototype DeICE-IT system to an operational system. The second is a business plan to take the operational DeICE-UT system to market and turn it into a profitable combination of products and services.
o There is a degree of overlap between the two, but the business plan proper cannot be completed until the final demonstration of the operational DeICE-UT system has taken place and its performance has been measured. Only then, for example can its benefits over existing technology be defined and an important element of the business plan defined. On the other hand, the development plan requires financing and if private financiers or banks are to be approached, they will require a business plan.
o The DeICE-UT project aimed only to produce a prototype that was demonstrated in a relevant environment, in this case the environmental chambers at Motor Industry Research Association (MIRA) Technology Park, near Nuneaton in the UK. This corresponds to a Technology Readiness Level (TRL) of 6.

Potential Impact:
Wind energy is the most popular renewable energy technology both globally and within the EU due to the availability of wind resources and the relative simplicity of the technology. Wind energy currently provides approximately 6% of the overall European electricity production and its expansion into cold climates is inevitable. Here icing on any exposed part of the turbine can occur in the form of wet snow, freezing rain or drizzle, or in-cloud icing. Icing decreases performance of the turbine and therefore the successful solution to the problem proposed by the DeICE-UT system will have a significant strategic impact. The successful implementation of the key deliverables of the DeICE-UT project will enable the SMEs involved to exhibit sustainable growth which will be in line with the growth expected for the wind energy industry overall. Furthermore, the project will contribute towards the improvement of the wind power generation competitiveness in comparison to fossil fuels and other competing energy production methods.

The final cost of installation of the DeICE-UT technology into (3-5MW) wind turbines can only be approximated at this time and in addition will be dependent on a number of factors such as turbine size. More accurate costing of the technology will be undertaken within the project. However, based on our initial design, we estimate the cost of an installed DeICE-UT system to be €40k per installation. From the additional wind turbines planned in Europe, only a 6% market penetration by 2020 should yield revenue of Euro 86M giving the SMEs a return of 45:1 on their investment. At a societal level, DeICE-UT will increase the number of available jobs in the EU wind energy industry in line with economic growth, reduce the need for dangerous maintenance work in cold climates by inspection personnel, further promote the involvement of female employees in a male-dominated industry, contribute to sustainable industrial growth within Europe, increase public confidence in renewable energy sources across Europe, enable wind farms to be located in areas with optimum conditions, away from populated areas and optimise the production of European wind farms in Icing regions - year round production. A road-map has been developed for taking the DeICE-UT system beyond the prototype stage, which will include thorough market research, a business plan for attracting new finance and a projected work plan to raise the system’s technology readiness level.

The final results of the project were, first; a prototype combined Guided Ultrasonic Wave (GUW) and vibration de-icing system, second; a high-powered SH-wave resonating shield, third; a low temperature controller for the both de-icing and ice detection systems, fourth; a compact shaker, fifth; a new blade design with GUW guard inserted into the leading edge and fifth; a service for retrofitting GUW guards on existing wind turbine blades.

The SH-wave resonating shield, consisting of an array of small shear-motion stacked actuators bonded to a metal strip of which the width is used to determine the resonance frequency is a completely new development of GUW ultrasonics. Its ability transfers high power SH-waves over long distances has many other applications, including the prevention of bio-fouling and transmission of ultrasound energy through ice barriers.

The project has helped the SME-partners in the project develop their respective businesses. Also it has nurtured further a desire for further collaboration, both in taking the prototype forward to an operational system and for finding new applications for the novel high-powered SH-wave shield.

For the wider socio-economic impact of the project, it contributes to greater use of wind energy in colder climates, where increased wind speeds provide more efficient power and where sparsely populated areas reduce the visual impact of wind-turbines on the environment.

List of Websites:
http://www.deice-ut.eu/

Final Report Summary - DEICE-UT (Wind turbine blade Anti / De-icing, combined Ultrasonic guided wave and vibration system)

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