Browsing by Author "Zaghari, Bahareh"

Now showing 1 - 14 of 14
  • Thumbnail Image
    ItemOpen Access
    Application of model-based systems engineering for the integration of electric engines in electrified aircraft
    (IOP Publishing, 2023-06-28) Kiran, Abhishek; Zaghari, Bahareh; Kipouros, Timoleon; Nunes Dos Reis, Ricardo Jose
    The objective of green, carbon-neutral flights is propelling the innovation of newer propulsion systems. With this increased development of an interdisciplinary form of propulsion for aircraft, the integration burdens and efforts intensify. In literature, it is estimated that it takes 10-15 years to design and develop an aircraft. The expected date of entry for any hybrid electric aircraft is 2035-2040. Any innovation and effort to cut this time by any degree should be explored and analysed. One of the techniques that have the potential to help fast-track the research and development of interdisciplinary systems is Model-based System Engineering (MBSE). Various studies have shown the benefit of employing a model-based design strategy. The focus case study relates to the integration of the electric machine and the propeller, along with related sub-systems. For Hybrid Electric Propulsion (HEP), the electric machine and propeller need to be integrated and their interaction to be analysed. MBSE is proposed as a methodology that would help streamline the process of design and integration of the two systems. This study documents the exploration of connecting MBSE with current simulation and modelling of sub-systems in order to ensure the fulfilment of stakeholder needs and full system effectiveness. This paper establishes the research problem, and the approach to be pursued, and gives notice of first developments and expected follow-up work.
  • Thumbnail Image
    ItemOpen Access
    Application of probabilistic principles to set-based design for the optimisation of a hybrid-electric propulsion system
    (IOP, 2022-02-15) Spinelli, Andrea; Anderson, Luchien; Balaghi Enalou, Hossein; Zaghari, Bahareh; Kipouros, Timoleon; Laskaridis, Panagiotis
    Current research in hybrid-electric aircraft propulsion has outlined the increased complexity in design when compared with traditional propulsion. However, current design methodologies rely on aircraft-level analysis and do not include the consideration of the impact of new technologies and their uncertainty. This can be a key factor for the development of future hybrid-electric propulsion systems. In this paper, we present a methodology for exploring the design space using the principles of Set-Based Design, which incorporates probabilistic assessment of requirements and multidisciplinary optimisation with uncertainty. The framework can explore every design parameter combination using a provided performance model of the system under design and evaluate the probability of satisfying a minimum required figure of merit. This process allows to quickly discard configurations incapable of meeting the goals of the optimiser. A multidisciplinary optimiser then is used to obtain the best points in each surviving configuration, together with their uncertainty. This information is used to discard undesirable configurations and build a set of Pareto optimal solutions. We demonstrate an early implementation of the framework for the design of a parallel hybrid-electric propulsion system for a regional aircraft of 50 seats. We achieve a considerable reduction to the required function evaluations and optimisation run time by avoiding the ineffective areas of the design space but at the same time maintaining the optimality potential of the selected sets of design solutions.
  • Thumbnail Image
    ItemOpen Access
    Application of probabilistic set-based design exploration on the energy management of a hybrid-electric aircraft
    (MDPI, 2022-03-08) Spinelli, Andrea; Balaghi Enalou, Hossein; Zaghari, Bahareh; Kipouros, Timoleon; Laskaridis, Panagiotis
    The energy management strategy of a hybrid-electric aircraft is coupled with the design of the propulsion system itself. A new design space exploration methodology based on Set-Based Design is introduced to analyse the effects of different strategies on the fuel consumption, NOx and take-off mass. Probabilities are used to evaluate and discard areas of the design space not capable of satisfying the constraints and requirements, saving computational time corresponding to an average of 75%. The study is carried on a 50-seater regional turboprop with a parallel hybrid-electric architecture. The strategies are modelled as piecewise linear functions of the degree of hybridisation and are applied to different mission phases to explore how the strategy complexity and the number of hybridised segments can influence the behaviour of the system. The results indicate that the complexity of the parametrisation does not affect the trade-off between fuel consumption and NOx emissions. On the contrary, a significant trade-off is identified on which phases are hybridised. That is, the least fuel consumption is obtained only by hybridising the longest mission phase, while less NOx emissions are generated if more phases are hybridised. Finally, the maximum take-off mass was investigated as a parameter, and the impact to the trade-off between the objectives was analysed. Three energy management strategies were suggested from these findings, which achieved a reduction to the fuel consumption of up to 10% and a reduction to NOx emissions of up to 15%.
  • Thumbnail Image
    ItemOpen Access
    E-textile technology review - from materials to application
    (IEEE, 2021-07-02) Komolafe, Abiodun; Zaghari, Bahareh; Torah, Russel; Weddell, Alex S.; Khanbareh, Hamideh; Tsikriteas, Zois Michail; Vousden, Mark; Wagih, Mahmoud; Jurado, Ulises Tronco; Shi, Junjie; Yong, Sheng; Arumugam, Sasikumar; Li, Yi; Yang, Kai; Savelli, Guillaume; White, Neil M.; Beeby, Steve
    Wearable devices are ideal for personalized electronic applications in several domains such as healthcare, entertainment, sports and military. Although wearable technology is a growing market, current wearable devices are predominantly battery powered accessory devices, whose form factors also preclude them from utilizing the large area of the human body for spatiotemporal sensing or energy harvesting from body movements. E-textiles provide an opportunity to expand on current wearables to enable such applications via the larger surface area offered by garments, but consumer devices have been few and far between because of the inherent challenges in replicating traditional manufacturing technologies (that have enabled these wearable accessories) on textiles. Also, the powering of e-textile devices with battery energy like in wearable accessories, has proven incompatible with textile requirements for flexibility and washing. Although current e-textile research has shown advances in materials, new processing techniques, and one-off e-textile prototype devices, the pathway to industry scale commercialization is still uncertain. This paper reports the progress on the current technologies enabling the fabrication of e-textile devices and their power supplies including textile-based energy harvesters, energy storage mechanisms, and wireless power transfer solutions. It identifies factors that limit the adoption of current reported fabrication processes and devices in the industry for mass-market commercialization.
  • Thumbnail Image
    ItemOpen Access
    Energy harvesting: an overview of techniques for use within the transport industry
    (IEEE, 2022-04-14) White, Neil M.; Zaghari, Bahareh
    This article introduces the various energy harvesting mechanisms that can be used to energize sensing systems and associated wireless communication channels. It outlines energy scavenging techniques, along with an assessment of useful materials for each mode of harvesting.
  • Thumbnail Image
    ItemOpen Access
    The impact of electric machine and propeller coupling design on electrified aircraft noise and performance
    (AIAA, 2023-01-19) Zaghari, Bahareh; Kiran, Abhishek; Sinnige, Tomas; Pontika, Evangelia; Enalou, Hossein B.; Kipouros, Timoleon; Laskaridis, Panagiotis
    Novel propulsion systems have been studied in literature to reduce aircraft emissions with hydrogen or other electrical energy sources. Hybrid Electric Propulsion (HEP) system consists of electric machines as an alternative way to provide power for propulsion resulting in the reduction of aircraft fuel consumption. While reduction of emission is the main driver of new HEP designs, aircraft noise reduction and performance improvement will also need to be investigated. Much quieter electrified aircraft than conventional aircraft is explored with considering the benefits of coupled design between the propeller and electric machines. In this study, several electric machine designs have been explored and coupled with the propeller design to study the trade-off between the aerodynamic and acoustic performance of the propeller. Aerodynamic optimization is used as a baseline to minimize the energy consumption to find the aerodynamics optimum subject to constraints on the thrust levels during the mission. The propeller aerodynamic optimizer considers the electric machine efficiency map, which is a function of propeller torque and rotational speed, to find the optimum combination of propeller and electric machine designs. The objective function of the acoustic optimizations is to reduce the cumulative noise level over the entire mission. It is shown that a wider envelope of peak motor efficiency in the efficiency map provides acoustics and aerodynamic performance benefits. The trade-offs between reducing noise or increasing aerodynamic efficiency to reduce energy consumption are demonstrated.
  • Thumbnail Image
    ItemOpen Access
    The impact of multi-stack fuel cell configurations on electrical architecture for a zero emission regional aircraft
    (AIAA, 2023-01-19) Zaghari, Bahareh; Zhou, Tianzhi; Enalou, Hossein B.; Pontika, Evangelia; Laskaridis, Panagiotis
    All-electric aircraft can eliminate greenhouse gas emissions during aircraft mission, but the low predicted energy storage density of batteries (=0.5 kWh/kg), and their life cycle, limits aircraft payload and range for regional aircraft. Proton Exchange Membrane Fuel Cells (PEMFCs) using hydrogen are explored as an alternative power source. As the effort on designing high power density and highly efficient fuel cell systems continues, a trade off study on the effect of fuel cell configurations and the electrical conversion strategy on system efficiency, total weight, failure cases, and reduction of power due to failures, will inform future designs. Introducing viable fuel cell stacks and electrical configurations motivates such a trade off study, as well as concentrated design effort into these components. Currently available fuel cell stacks are designed at lower power (in the range of 150kW) to what is required for regional aircraft propulsion (in the range of 4MW). Hence to achieve the total required power, the fuel cell stacks are connected in parallel and series to create multi-stack configurations and provide higher power. In this study, multi-stack fuel cell configurations and the selected DC/DC converters are assessed. Each configuration is evaluated based on power converter design and redundancy, design for high voltage, degradation of fuel cell stacks, total system efficiency, and controllability of fuel cell stacks.
  • Thumbnail Image
    ItemOpen Access
    Integrated mission performance analysis of novel propulsion systems: analysis of a fuel cell regional aircraft retrofit
    (AIAA, 2023-01-19) Pontika, Evangelia; Zaghari, Bahareh; Zhou, Tianzhi; Enalou, Hossein B.; Laskaridis, Panagiotis
    This paper presents the development and application of an integrated, higher-fidelity framework developed within CHARM (the Cranfield Hybrid electric Aircraft Model) for the design, performance analysis and overall evaluation of novel electrified propulsion systems. The developed framework is used to model and analyze the performance characteristics of a Fuel Cell (FC) regional aircraft system in comparison with a conventional regional aircraft and a hydrogen gas turbine regional aircraft retrofit. The FC propulsion system and the hydrogen gas turbine are retrofitted to the same conventional aircraft platform. Physics-based aircraft performance calculations, propeller maps, gas turbine component maps, off-design cycle analysis, electric component maps, calculations for the electric power management and distribution, and a Proton-Exchange Membrane FC (PEMFC) configuration sized to cover the power requirements of a regional aircraft, are integrated within this framework to capture the performance and interaction of components, sub-systems and aircraft during any flight mission and conditions. The aircraft performance, the propulsion system performance characteristics and the emissions of the three technologies are calculated and discussed to understand the challenges and opportunities of using hydrogen-electric propulsion (FC). The effect of capturing the variable mission parameters and flight phases on the performance of the electric power system and FC is presented and compared against a lower fidelity modeling approach for the electric powertrain. The sensitivity of the FC propulsion system and its attributes to varying mission requirements (island-hopping, range, cruise altitude, ambient conditions), as well as the change in the consumed fuel, are demonstrated. This framework can be used to inform the decision-making for the design of electric components and thermal management systems (TMS), and the importance of capturing the trade-off between mass, efficiency and operational constraints in the design process is highlighted. Also, the off-design performance of the electric power system designs and FC is modeled to decide if the design is within acceptable limits under various conditions, and capture the effect of mission requirements and flight conditions on the energy consumption of the overall aircraft system. Finally, a parametric analysis addresses the effect of power density improvement with future technology on the energy per passenger and feasibility of the FC regional aircraft.
  • Thumbnail Image
    ItemOpen Access
    Minimising the effect of degradation of fuel cell stacks on an integrated propulsion architecture for an electrified aircraft
    (IEEE, 2022-07-07) Zhou, Tianzhi; Balaghi Enalou, Hossein; Pontika, Evangelia; Zaghari, Bahareh; Laskaridis, Panagiotis
    Proton Exchange Membrane Fuel Cells (PEMFC) are receiving interest as an electrical source of energy for aircraft propulsion electrification. However, their implementation challenges such as durability, reliability, and the dynamic behaviour of Fuel Cells (FCs) in an integrated hybrid propulsion system have not been fully explored. Currently, most commercial PEMFC stacks have maximum power close to 150kW. To achieve higher power required for aviation, these stacks can be connected in series and parallel to achieve high voltage required for propulsion. Poor design procedure of cells and stacks can cause variation between the stacks resulting in failure and fast degradation of the connected stacks. In this paper the impact of voltage and current drop of one stack, which could be caused by changes in the fuel cell’s individual axillary parts, degradation of the cells within the stack, or faults in the connections and distribution is explored. Upon exploring different configurations, it is found that the arrangements of FC stacks connections could help in reducing the impact of voltage and current variations due to degradation in each stacks. The imbalance stack performance and its effects on the whole energy storage system performance is not fully explored before. It is important to conduct quantitative analysis on these issues before the PEMFC system can be implemented.
  • Thumbnail Image
    ItemOpen Access
    Modelling and validation of a guided acoustic wave temperature monitoring system
    (MDPI, 2021-11-06) Yule, Lawrence; Zaghari, Bahareh; Harris, Nicholas; Hill, Martyn
    The computer modelling of condition monitoring sensors can aide in their development, improve their performance, and allow for the analysis of sensor impact on component operation. This article details the development of a COMSOL model for a guided wave-based temperature monitoring system, with a view to using the technology in the future for the temperature monitoring of nozzle guide vanes, found in the hot section of aeroengines. The model is based on an experimental test system that acts as a method of validation for the model. Piezoelectric wedge transducers were used to excite the S0 Lamb wave mode in an aluminium plate, which was temperature controlled using a hot plate. Time of flight measurements were carried out in MATLAB and used to calculate group velocity. The results were compared to theoretical wave velocities extracted from dispersion curves. The assembly and validation of such a model can aide in the future development of guided wave based sensor systems, and the methods provided can act as a guide for building similar COMSOL models. The results show that the model is in good agreement with the experimental equivalent, which is also in line with theoretical predictions.
  • Thumbnail Image
    ItemOpen Access
    A TEG-excited switched reluctance generator for self-powered sensing in next generation aircraft
    (AIAA, 2023-01-19) Zaghari, Bahareh; Stuikys, Aleksas; Weddell, Alexander; Grabham, Neil; White, Neil; Harvey, Terry; Wang, Ling
    New aircraft concepts are proposed to support emission reduction in aviation. To achieve the advantages of these concepts an electrical system with high power delivery and low system mass needs to be considered. The reduction of weight of all sub-components without compromising on reliability is being investigated. To achieve these self-powered systems can be introduced to monitor safety critical components. Locally embedded wireless self-powered systems can reduce the weight associated with health monitoring significantly compared to wired systems. In this paper a self-powered system that can be embedded in the engine is introduced. Switched reluctance generator integrated with a thermoelectric generator (TEG) is designed to provide power for bearing health monitoring. An efficient switched reluctance generator is designed for the limited amount of space in the aircraft engine. Two configurations for a six stator poles and fifteen rotor poles (6/15), three phase switched reluctance generator were compared and highest power output was obtained when the individual phase coils were connected in parallel. To achieve efficient energy conversion, the design process and selection of the excitation and generation angles played an important role.
  • Thumbnail Image
    ItemOpen Access
    Temperature hotspot detection on printed circuit boards (pcbs) using ultrasonic guided waves—a machine learning approach
    (MDPI, 2024-02-07) Yule, Lawrence; Harris, Nicholas; Hill, Martyn; Zaghari, Bahareh; Grundy, Joanna
    This paper addresses the challenging issue of achieving high spatial resolution in temperature monitoring of printed circuit boards (PCBs) without compromising the operation of electronic components. Traditional methods involving numerous dedicated sensors such as thermocouples are often intrusive and can impact electronic functionality. To overcome this, this study explores the application of ultrasonic guided waves, specifically utilising a limited number of cost-effective and unobtrusive Piezoelectric Wafer Active Sensors (PWAS). Employing COMSOL multiphysics, wave propagation is simulated through a simplified PCB while systematically varying the temperature of both components and the board itself. Machine learning algorithms are used to identify hotspots at component positions using a minimal number of sensors. An accuracy of 97.6% is achieved with four sensors, decreasing to 88.1% when utilizing a single sensor in a pulse–echo configuration. The proposed methodology not only provides sufficient spatial resolution to identify hotspots but also offers a non-invasive and efficient solution. Such advancements are important for the future electrification of the aerospace and automotive industries in particular, as they contribute to condition-monitoring technologies that are essential for ensuring the reliability and safety of electronic systems.
  • Thumbnail Image
    ItemOpen Access
    Temperature monitoring of through-thickness temperature gradients in thermal barrier coatings using ultrasonic guided waves
    (Springer, 2024-01-24) Yule, Lawrence; Harris, Nicholas; Hill, Martyn; Zaghari, Bahareh
    Ultrasonic guided waves offer a promising method of monitoring the online temperature of plate-like structures in extreme environments, such as aero-engine nozzle guide vanes (NGVs), and can provide the resolution, response rate, and robust operation that is required in aerospace. Previous investigations have shown the potential of such a system but the effect of the complex physical environment on wave propagation is yet to be considered. This article uses a numerical approach to investigate how thermal barrier coatings (TBCs) applied to the surface of many components designed for extreme thermal conditions will affect ultrasonic guided wave propagation, and how a system can be employed to monitor through-thickness temperature changes. The top coat/bond coat boundary in NGVs has been shown to be a temperature critical point that is difficult to monitor with traditional temperature sensors, which highlights the potential of ultrasonic guided waves. Differences in application method and layer thickness are considered, and analysis of through-thickness displacement profiles and dispersion curves are used to predict signal response and determine the most suitable mode of operation. Heat transfer simulations (COMSOL) have been used to predict temperature gradients within a TBC, and dispersion curves have been produced from the temperature dependant material properties. Time dependant simulations of wave propagation are in good agreement with dispersion curve predictions of wave velocity for the two lowest order modes in three thicknesses of TBC top coat (100, 250, and 500 μ ). When wave velocity measurements from the simulations are compared to dispersion curves generated at isotropic temperatures, the corresponding temperature represents the average temperature of a gradient system well. Such a measurement system could, in principle, be used in conjunction with surface temperature measurement systems to monitor through-thickness temperature changes.
  • Thumbnail Image
    ItemOpen Access
    Towards in-flight temperature monitoring for nozzle guide vanes using ultrasonic guided waves
    (AIAA, 2021-07-28) Yule, Lawrence M.; Zaghari, Bahareh; Harris, Nicholas; Hill, Martyn
    The temperature monitoring of nozzle guide vanes is a challenging task due to the extreme temperatures, gas pressures, and cramped conditions of aero-engines. Ultrasonic guided waves are an attractive method of temperature monitoring as the sensors can be placed outside of the gas path without influencing component operation. In this paper the suitability of using ultrasonic guided waves in the form of the S0 Lamb wave mode is investigated by comparing experimentally measured wave velocity change with temperature against theoretical wave velocity extracted from dispersion curves. Waves are transmitted through an aluminium plate using a pitch-catch wedge transducer configuration, and wave velocity is measured using across-correlation function. Temperature is controlled with a hot plate from room temperature to 100°C, and monitored using thermocouples. Results show that this transducer configuration is capable of monitoring a change in temperature based on a change in wave velocity, showing a good agreement with theoretical predictions, within 4.89+/-2.27 m/s on average. The temperature sensitivity of the system is 1.26–1.78 m/s/°C over the range 24°C–94°C. This shows the potential for a guided wave based temperature monitoring system, assuming a suitable transducer configuration can be found that is able to operate at higher temperatures. Further investigation will study the possibility of using Piezoelectric Wafer Active Sensors (PWAS) or waveguides for this application.