PhD, EngD and MSc by research theses (SATM)

Permanent URI for this collectionhttps://dspace.lib.cranfield.ac.uk/handle/1826/8739

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Access status: Open Access ,
Trajectory optimization with sparse gauss-hermite quadrature
(Cranfield University, 2023-04) Park, On; Shin, Hyo-Sang; Tsourdos, Antonios
This thesis aims to innovate knowledge on the trajectory optimization problem for aerospace applications by adopting a numerical integration in optimal control designs. Quadrature point scheme is considered to substitute a derivative of an optimal cost-to-go function and system dynamics approximated by Gaussian Quadrature rule. Based on the Differential Dynamic Programming (DDP) algorithm, a sequence of optimal control input is derived by sparsely chosen quadrature points with the Smolyak’s rule over an exponential weighting function on the Gaussian quadrature, called as Sparse Gauss-Hermite Quadrature (SGHQ). The sampling points propagated via system dynamics computes the mean and covariance of a probability distribution of the value function avoiding a numerical differentiation in the DDP. This approach improves an accuracy and robustness against the numerical calculation in the highly nonlinear environment despite the less number of the quadrature points compared with the fully composed by Gauss- Hermite Quadrature. Besides, the number of sampling points can be determined by Smolyak’s rule definitely, while the other sampling point-based approach chooses by heuristic/empirical method such as a trial and error. The proposed method is carried out and validate via numerical simulation: a fixed-wing aircraft controller and missile guidance. Considering a stochastic environment and control policy, trajectory optimization problem can be extended to a stochastic trajectory optimization and maximum entropy problem by adding an entropy term in a deterministic trajectory optimization problem: a Guided Policy Search (GPS). This entropy term in a stochastic problem enables to prevent a control policy from falling into local minima by maximizing exploration in the given unknown environment, and improves robustness to respond to a potentially flexible environment. A local policy is updated by DDP framework where the SGHQ-DDP can be implemented to find a mean and covariance of policy distribution by solving the soft Bellman equation. The numerical simulation shows the feasibility of the SGHQ-GPS method under an unknown system dynamics under the fitted model.
Access status: Open Access ,
Introduction of social benefits to the tera – gas turbines and pipelines
(Cranfield University, 2023-04) Ojo, Oluwatayo Babatope; Pilidis, Pericles; Igie, Uyioghosa
The aim of this work is the techno-economic and environmental risk analysis (TERA) of the Trans-Saharan Gas Pipeline on gas turbine compressor stations. A pipeline project encompasses many aspects, viz., choice of compressor station location, power of each compressor station, compressor station availability, pipeline sizing, and it includes socioeconomic impacts. Therefore, this research considered the impacts of engine availability, compressor station location, and socioeconomic impact in the TERA for pipelines while optimising for the lowest lifecycle cost. The pipeline and gas compressor modules were evaluated considering segmented pipe length, elevation, and station location ambient temperature variation at varying flow conditions. The design and off-design points performance of the selected gas turbine models were simulated using Turbomatch to obtain essential performance data required for the techno socio- economic analysis. The unit availability was evaluated based on a developed local maintenance schedule and failure rate retrieved from literature studies. The analysis considered the social impacts and benefits of compressor station locations. A scenario-based techno socio-economic analysis was performed to show the sensitivities of the compressor station and pipeline systems to social and technical aspects of the project in terms of social benefits and availabilities. The economic model was developed based on social benefit algorithms and the variation in compressor station location ambient temperatures at varying flow conditions. Results show compressor station system availabilities of 0.2542, 0.4657, and 0.9926 with corresponding lifecycle costs of $22.22 billion, $23.05 billion, and $24.11 billion assuming a 15% discount rate for scenarios 1, 2, and 3, respectively. An increase in availability leads to a corresponding increase in the lifecycle cost estimate. The employment and road benefit ratios would increase by a factor of 10 and reciprocal of new locations. This ratio is for every 10 km decrease in the distance at each station location. Results show the significance of the modelling and optimisation approaches utilised in this research for compressor station locations optimisation of the integrated pipeline TERA. This will guide decision-makers on the ultimate selection of engine configurations that will give the optimum lifecycle cost and socio-economic benefits at the optimised station locations.
Access status: Open Access ,
Design and analysis of sandwich structure for the application on FAR25 wing
(Cranfield University, 2021-12) Naik, Vivekanand K.; Wenli, Liu; Jamshidi, Jafar
With the growing concern towards global warming and increase in fuel prices, many countries advocate stringent environmental laws to restrict any further damage to the environment. The new laws will affect how the future vehicles are designed. The aerospace industry is also one of the main contributors of pollution. To design better fuel-efficient aeroplanes, aero industry is switching to weight efficient materials. Since last few decades the aerospace industry is shifting from isotropic materials to composite materials to design weight efficient structures. The structures made up of composite materials are mostly in two different forms such as monolithic composite materials used on primary structures and composite sandwich materials which are commonly seen on the secondary structures. The research aims at investigating the sandwich structure as the potential material for the application on FAR25 type wing primary structure. The transport category airplanes with greater than 19 sets or the maximum take of weight (MTOW) is greater than 8618kg are referred to FAR25 type aeroplanes. In the first phase of the research, the focus is to assess the literature to find research gaps within the sandwich structures along with feedback from Airbus Research and Technology (R&T). In second phase, the focus is to investigate the stiffened panel design which is based on the current Airbus single aisle aeroplane. The review of sandwich structures and its current application on FAR25 structures along with the current research and development of sandwich material technology is conducted. The different failure modes of the sandwich structures are also investigated. In the third phase, parametric study and optimization of stiffened panel and sandwich panel is performed within the range of operational loads. In addition, the influence of core properties in improving the structural efficiency of sandwich structure is investigated. The research also focused on understanding the efficiency of different sandwich joints. In the final phase of the research the study looks into the design of hybrid/variable stiffness core to help tailoring core properties to improve the structural efficiency of sandwich panel. The research study demonstrated the importance of core properties in designing the efficient sandwich panel as potential material for the application on FAR25 primary structure. Investigation of novel variable core design has demonstrated how the tailoring of core properties can influence the overall performance of sandwich structure so that the core can be tailored as per different application. From the research it has shown that the sandwich core with single property structure can be still used on secondary structure whereas the tailored core design for the primary structure on FAR25 type aeroplanes. It is also shown that a better manufacturing process can add considerable value for sandwich materials.
Access status: Open Access ,
Propulsion integration design and evaluation for novel aircraft configurations
(Cranfield University, 2022-10) Matesanz Garcia, Jesus; MacManus, David G.
To comply with the future environmental requirements for the aviation industry, it is necessary to move towards more efficient aircraft and propulsive systems. Within this context, different novel aircraft concepts have been introduced to increase overall propulsive efficiency compared with the current technologies. A common characteristic between these concepts is the close integration of the propulsive system within the airframe. As a consequence, the impact of the propulsion integration on the aerodynamic performance of the aircraft is expected to increase in comparison with the conventional wing-mounted podded engines. However, with a few exceptions, for these new configurations the impact of the propulsion integration on the aerodynamic performance has not been sufficiently quantified. The aim of this research is to establish the methods for the aerodynamic design of the propulsion integration of the novel embedded propulsion systems. These methods are then used, for an example configuration, to quantify the impact of the propulsion integration in the overall aerodynamic performance and characteristics. A systematic design methodology was developed for the aerodynamic analysis of embedded propulsion systems. This methodology includes the parametric definition of the geometry, the aerodynamic evaluation of the propulsor, and a tailored postprocessing approach. An aft-mounted annular boundary layer ingestion propulsor for a medium-range single-aisle aircraft is used as a sample case study. A hierarchical approach with an increasing level of fidelity was applied to determine the modelling requirements for the embedded propulsion systems. This involved low order methods for drag prediction and computational fluid dynamics (CFD) methods. The CFD methods included two different fan approaches (one-dimensional and through-flow), as well as 2D axisymmetric and 3D models. To understand the limits of the design space, the design methodology was combined with a multi-objective optimisation (MOO) approach based on evolutionary algorithms. In a preliminary analysis, power savings for the whole aircraft between 3-11% were predicted due to the integration of the aft-mounted propulsor. Compared with the CFD analyses, low order models for the prediction of the aerodynamic performance found in the open literature overpredicted the power savings in approximately a 50%, making them unsuitable for the evaluation of the aerodynamic performance in embedded systems. A comparison of the modelling fidelity of the different CFD approaches shown a reduction of approximately 2% of the power savings from the original 3-11%, when 2D axisymmetric models are applied instead of more representative 3D approaches. However, the 2D axisymmetric models had about 1% of the computational cost of the 3D versions. The application of a more representative through-flow fan model also increased the predicted power savings by up to 1-1.5% when compared with a one dimensional fan. The location of the aft-mounted propulsor was found to have a significant impact on the aerodynamic performance of the embedded propulsor and the predicted power savings. Relative to the overall benefits in the power consumption of ∼ 11%, variations of approximately 4-5% on the predicted power savings are observed with the change of the propulsor axial and radial location. Locations near to the fuselage centreline are preferred. Short aft-fuselage lengths with a low fan radius of the aft mounted propulsor provided the highest thrust contribution and power savings. The more detailed design of the housing components (intake, nacelle and exhaust) of the aft-mounted propulsor has a second order impact in comparison with the propulsor location. At a fixed propulsor position, an increase of up to 1.5% of the power savings was obtained with the MOO of the aerodynamic design of the propulsion integration. From these changes, approximately one-third was obtained with the optimisation of the exhaust design, while the remaining benefits were obtained with the optimisation of the aft-fuselage, intake and nacelle geometries.
Access status: Open Access ,
Visual-based automated aircraft inspections for 3d skin damage
(Cranfield University, 2022-09) Lafiosca, Pasquale; Fan, Ip-Shing; Avdelidis, Nico
Visual inspection is the common mean to detect damages on the aircraft skin. Standard maintenance programmes require engineers to perform frequent inspections that are costly, time consuming, hazardous and subject to human factors. Engineers are required to inspect all the areas, including crown, wings and vertical stabiliser, and personally evaluate the damage. Dents, in particular, are flaws that are challenging to detect and measure due to undefined boundaries, complex geometry and difficult access. Because of these characteristics, dents cannot be detected by monocular cameras and automation of their inspection has been lacking momentum, generally limited to manually operated 3D scanning tools. Moreover, no solution has been explored to replace the human judgement of the damage. The aim of this work is the design of an automatic system to inspect the aircraft skin, identify dents, measure and report them to the engineer, thus demonstrating the feasibility of such autonomous task via unmanned aerial vehicles. After reviewing the state of the art, data is acquired by means of a single-shot structured-light algorithm for 3D scanning based on Fourier transform profilometry and compatible with the use of un- manned aerial vehicles, yet delivering submillimetre accuracy. Machine learning is then considered for the autonomous identification of dents, implemented through a novel point cloud segmentation algorithm. Finally, a mathematical model is proposed to evaluate dent shapes, replacing the current reporting standards by allowing accurate and comparable dimensional evaluation. The three main contributions operate together to enable autonomous aircraft dent inspections, whose feasibility is demonstrated by experiments with a prototype system. This work paves the way for future automated systems capable to increase safety and advance aircraft inspection reliability, while reducing human workload, downtime and thus costs.
Access status: Open Access ,
Differential flatness based flight control of tilt-rotor VTOL aircraft
(Cranfield University, 2021-11) Joseph, Emmanuel Biju; Whidborne, James F.; Chen, Lejun
Urban Air Mobility (UAM) is identified as the future of mobility, and several airframes are being trialled to fit air transport within modern cities. Speed and efficiency are the primary requirements deliberated for UAM Vertical Take-off and Landing (VTOL) aircraft, and configurations incorporating tilt-rotors and tilt-wings have been identified as viable solutions. For quadrotors and robotics, control techniques leveraging the differentially flat property of system dynamics have achieved significantly improved tracking performance and motivated the application of this control technique for VTOL aircraft. This study proposes a novel control architecture based on the differential flatness property of aircraft kinematics, to improve controller performance for autonomous flight. A conceptual validation of the proposed technique was implemented on a Planar VTOL (PVTOL) model as a precursor to the research. Consequently, an architecture for implementing the concept in tilt-rotor VTOL aircraft (Aston Martin Vision Volante) was devised, implemented, and tested. The control architecture achieved the speculated performance improvements and lays foundation for further research and development into the proposed control technique.
Access status: Open Access ,
Wire + arc additive manufacturing for high-speed flight
(Cranfield University, 2023-01) James, William Sean; Ganguly, Supriyo; Rodrigues Pardal, Goncalo
The use of Wire + Arc Additive Manufacturing (WAAM) to manufacture high- speed projectiles, such as missiles, is currently an industry challenge due to the nature of high-speed flight and the extreme environment that components are exposed to. Alloys that are suitable for high-speed flight are creep resistant superalloys, this is due to the aggressive heating environment experienced by objects in high-speed flight, and the need for performance at extremely high temperatures. These materials are currently expensive and difficult to manufacture, which is less than ideal for non-recoverable systems such as airborne weapons. The development of missile systems requires flight tests to be affordable and operate in quick succession, to which rapid prototyping offers a significant advantage. The use of traditional manufacturing methods and supply- chain for this purpose are logistically challenging and expensive, mainly due to loss of material though machining. The use of WAAM in a rapid prototyping capability is the driver for this research. To be able to use the process to manufacture and prototype components for high-speed applications, would, if possible, be an excellent solution to reducing the amount of time and money that it currently costs to flight-test and develop these systems. WAAM could also be used for final design production. The effect WAAM route has on the high temperature properties of superalloys is largely unknown. This research is therefore focused on the development of the WAAM process, and selection of alloys suitable for high-speed flight and for WAAM deposition. Four creep-resistant superalloys underwent deposition using a plasma WAAM process and the resulting material was characterised to understand how WAAM affects high temperature performance. The research also investigates post-deposition heat-treatment of these alloys and develops parameters for inter-pass machine hammer peening to improve material performance. The findings from this project increases the understanding between the WAAM process and superalloy strengthening mechanisms and develops a method to increase the performance of additive manufactured material. The mostii appropriate alloys for both WAAM and the high-speed flight application were ranked and down selected based on their anticipated performance and weldability. The selected alloys then underwent extensive testing from room temperature to 1000 °C, to understand the performance of WAAM built structures at high temperature. The microstructure is examined throughout and found key differences between solid-solution strengthened and age hardened alloys which effects performance. Finally, in-process machine hammer peening was investigated for age hardened Rene 41 and found to greatly increase the performance to match that of the wrought material.
Access status: Open Access ,
Framework for anomaly detection of flight-crew deviation from standard operating procedures: a data analytics approach
(Cranfield University, 2022-05) Igenewari, Vivian Rowoli; King, Steve; Jennions, Ian K.
Deviations from Standard Operating Procedure form a significant part of aviation incidents today involving loss of lives and other related costs. Previous work tailored towards detecting procedure deviations in flight operations have primarily been rule-based. The current method being used by airlines to detect operational, component fault and crew action anomalies within flight data is a rule-based Exceedance Detection technique which is only able to flag up known flight abnormalities. Lately, Anomaly Detection methods have been introduced to find, not just known, but unknown anomalies that deviate from the expected normal flight profile. There is a need to explore flight data using anomaly detection methods to detect subtle underlying misunderstandings of the flight crew in relation to deviations from laid down procedures which do not lead to incidents, under most conditions, or are hard to detect by the state-of-the-art method. However, these detection methods are limited in the type of anomalies they can find when implemented individually on heterogeneous flight dataset thereby missing critical anomalous flight incidents. In this work, Flight Data Recorder data of a fleet from a United Kingdom airline and a structurally similar publicly available dataset from the National Aeronautics & Space Administration are used. This study proposes a framework integrating an Ensemble anomaly detection technique (combining individual anomaly detection techniques into a single method) and a Case Based Reasoning system. The findings reveal that combining existing anomaly detection methods into an Ensemble can detect a wider variety of anomalies that were not flagged by individual methods. Also, the proposed reasoning design aims to filter for procedure deviations from the pool of anomalous incidents detected by the Ensemble. Detecting these procedure deviations is not just aimed at complementing crew training, improving procedures, and understanding automation design to put in place mitigation strategies but also to aid accident investigations by informing of accident flights with procedure deviations that may have been contributing factors.
Access status: Open Access ,
Techno-economic, environmental and risk analysis of a hydrogen airliner family market entry
(Cranfield University, 2022-11) Huete Anton, Jon; Pilidis, Pericles; Adams, Richard
Civil aviation is in a profound transition motivated by the need to reduce its environmental impact. Most civil aviation institutions and stakeholders are now committed to reach net zero by 2050, though there is no feasible path drafted to achieve this goal. Projected energy efficiency improvements, and the use of sustainable aviation fuels could provide a significant reduction in CO₂ emissions, but to reach net zero all emissions should be eliminated or compensated, and none of these solutions achieve the target. Hydrogen as fuel has zero emissions of CO₂ and can address aviation non-CO₂ emissions in an effective manner, to become a true zero emission alternative. Optimising a hydrogen aircraft to match the capabilities and flexibility of the existing narrowbody or the widebody point to point ultra-long-range capacity will take decades. An speculative alternative to expedite the introduction of hydrogen aircraft using existing technology is the focus of this research. A second and third generation of hydrogen aircraft could bring additional benefits in terms of capability and fuel consumption. But the first generation is focused on a swift change. An evaluation of the capabilities achievable with today’s technology and tube and wing configuration is performed. A redesigned double deck aircraft using the A380 as a baseline, with modified wings and engines, and with a variety of tank configurations is investigated as an initial airliner family. It can provide passenger capacities of 388 to 232 with a range of 3,300 nm to 5,600 nm, respectively. Such airliner family could start decarbonising the long-range sector in 15 years. It offers potential to go one-stop to anywhere in the world. A high-capacity version can travel 1,800 nm with 720 passenger is also studied as a solution for high demand city pair traffic. These findings were presented in ISABE 2022 and ICAS 2022 and published in the ISABE special issue of the Aeronautical Journal. The paper ‘Propulsion System Integration for a First-Generation Hydrogen Airliner’ was awarded a Bronze Prize by the RAeS in 2022 and was the 5th most downloaded paper in 2022 in the Aeronautical Journal with 1599 downloads.ii Cryogenic storage is one of the most critical technologies to be addressed. Lightly insulated tanks can extend the range of the aircraft for a given tank volume, but they are unlikely to be used in a first generation due to the need to manage the vented vapour at the airport. Tank architecture and configurations are explored to understand the current and future implications, finding that diameter and dormancy time requirements are the key design parameters that drive the weight of the tank. This work significantly contributed to win three work packages for ATI managed FlyZero project – Tank Design, Fuel System and Combustion consultancy and Advanced Propulsion – where the methods developed in the thesis were adopted. Particularly relevant was the tank weight finally assumed by FlyZero due to the outcomes of this work, which was half the value assumed in most recent studies. A final exploration looks at the emissions that this swift change route could lead to. Complete decarbonization is not achieved until 2080, despite the early introduction in 2035 of the hydrogen airliners. Nevertheless, it provides a decarbonizing solution superior in the long term to other the solutions being explored based on biofuels.
Access status: Open Access ,
Dual-wavelength laser speckle technique for absolute angle sensing In two dimensions
(Cranfield University, 2022-06) Gibson, Samantha Jayne; Charrett, Thomas O. H.; Tatam, Ralph P.
This thesis presents the theory, development, and construction of a novel absolute angle sensor employing dual-wavelength laser speckle for use in measuring two dimensional surface tilt angles. The targeted application is robotic manufacturing, specifically robot drilling where perpendicularity to the workpiece is particularly important and an accuracy of up to 0.1° is desired. The proposed technique uses two collinear beams of differing wavelengths, illuminating the surface of interest. The generated speckle patterns are shifted with respect to each other, with the position and orientation of the shift being directly related to the two dimensional tilt of the surface. This relationship is derived mathematically, and a number of experimental results are presented to confirm its validity. Two full implementations of the sensor were tested and characterised. The first used a single laser outputting two longitudinal modes with a wavelength separation of 0.5nm. Initial results in one dimension presented measurements over the wide angle range of ±45.00°, with an average absolute bias error of around 0.51°. These errors were smaller at smaller magnitudes, averaging around 0.22° between ±11.2°. Further experiments in two dimensions focused on the magnitude range ±7.50°, finding average absolute bias errors of 0.15° in θx and 0.08° in θy. The estimated standard deviations in these measurements were 0.10° in θx and 0.18° in θy. The second sensor used two separate lasers with a wavelength separation of 21.5nm, increasing the sensitivity by a factor of 40. This sensor showed greater wavelength instability due to the two independent lasers and an increased mode instability. As such, the overall errors in experimental results were greater than expected, and the data were filtered to demonstrate the achievable performance if this laser instability were resolved. Results for surface tilts up to ±0.25° in two dimensions showed average absolute bias errors of 0.007° in θx and 0.009° in θy after filtering, and standard deviations of 0.003° in θx and 0.017° in θy. These results demonstrate that the dual-wavelength speckle technique has the potential to provide high accuracy absolute angle measurements in two dimensions.
Access status: Open Access ,
Conceptual design methodologies appropriate to blended wing body aircraft with boundary layer ingestion
(Cranfield University, 2021-12) Gao, Ziang; Smith, Howard; Zare Shahneh, Amir
Blended wing body aircraft equipped with boundary layer ingestion technology represent a paradigm leap in aircraft design, one that provides significant aerodynamic and environmental benefits while reducing fuel consumption. Although there are numerous advantages to this structure, there are also various issues that arise as a result of the highly integrated nature of the configuration and the disciplinary couplings that ensue. This project develops a conceptual design methodology appropriate to the blended wing body commercial passenger transport with boundary layer ingestion and applied this methodology into the Cranfield multidisciplinary design analysis and optimisation environment – GENUS. The GENUS framework integrates a variety of aerodynamic analysis tools, an efficient geometry parameterization method, a semi-empirical mass breakdown model, and an effective boundary layer ingestion analysis model to enable the synthesis of a realistic conceptual design and exploration of the design space for this novel class of aircraft. The comparative case studies of blended wing body airplanes and conventional airplanes in three different sizes find that the blended wing body is more advantageous at larger aircraft sizes, which achieve 10.4% reduction in fuel consumption for 14000km-mission-range, 555- passenger class and the benefit could be expanded to 16.9% with the application of boundary layer ingestion. The parameter sensitivity analysis shows that the central body sweep is a key parameter for the design of the blended wing body aircraft, and the optimal central body sweep with the minimum fuel consumption increases as the cruise Mach number increases. In the final optimisation part, the geometry at Mach 0.74 has the lowest fuel consumption, but the one at Mach 0.86 has the highest productivity. The optimised geometry with boundary layer ingestion leads to a 10.8% reduction in the fuel consumption but an 0.8% higher structure weight compared to the optimised geometry without boundary layer ingestion.
Access status: Open Access ,
Phase-Based Motion Magnification in outdoor conditions: Robustness and Natural Frequency extraction
(Cranfield University, 2021-12) El Sayah, Thierry; Petrunin, Ivan; Zanotti Fragonara, Luca
In this study, Phase-Based Motion Magnification is combined with 2D Point Tracking to enhance data extraction under noisy outdoor conditions. The aim is to investigate whether the use of Phase Based Motion Magnification along with 2D PT can increase accuracy of frequencies extracted in robust conditions. The study presents three experiments: a fixed wing on a shaker machine, a light pole and a building. Frequencies are extracted in all three experiments and compared against previous research and finite element analysis. Finally, the study touches on ways to automate the suggested procedure.
Access status: Open Access ,
An experimental investigation of a full-scale aircraft ECS
(Cranfield University, 2022-04) Chowdhury, Shafayat Hasan; Jennions, Ian K.; Ali, Fakhre
Aircraft Environmental Control System (ECS) conditions hot bleed air and regulates to the cockpit, cabin and avionics bay. It consists of multiple subsystems which are prone to degradation and eventually failure. There has been a number of incidents reported of sudden cabin pressure loss resulting in emergency landing. Such incidents at high altitudes can be problematic. Furthermore, the ECS has been reported to be a major driver for unscheduled maintenance impacting the operating costs. The development of an accurate diagnostic solution would identify the degradation early, hence, ensuring safety and reduction in maintenance costs. Researchers in the past have adequately studied model-based diagnostic techniques for the ECS at a component level. However, the ECS being an integrated system, the interdependencies between components makes the diagnosis difficult, particularly when the valves within the ECS masks fault occurrences and the fault propagates through the system. For this reason, IVHM centre has developed an ECS simulation model, SESAC, which has the capability to perform healthy and component degradation simulation. This PhD focuses on an experimental investigation on the ECS to facilitate verification of SESAC. A novel ground test facility (GTF) is developed on a Boeing 737-400 aircraft. The GTF is used to produce data under different ambient and operating conditions, which is used for PACK performance analysis. The importance of appropriate design of control system for ECS simulation model has been highlighted in this research. Furthermore, aircraft data has been used to provide understanding of the ECS control system. The control logic within SESAC has been fine-tuned to support heat exchanger degradation and valve malfunction simulation studies have been conducted. The ability of the 737-GTF to capture fault occurrence has also been demonstrated using experimental data.
Access status: Open Access ,
Towards a CubeSat relevant mission payload for demonstrating aspects of In-Situ ResourceUutilisation (ISRU) on a C-type Near-Earth Asteroid (NEA)
(Cranfield University, 2022-01) Chindo, Aminu Musa; Cullen, David C.; Pau, Joan; Cuartielles, Sanchez
Nearly 50 years ago, humankind long dreamed of colonizing or exploiting the neighbouring planets Mars, the Moon, comets, and asteroids in our Solar System for technological and profit-oriented purposes. The concept of In-Situ Resource Utilisation (ISRU) is likely to be a means to achieving those dreams. High cost and the possibilities of failure associated with the development of full-size ISRU spacecraft, early use of CubeSat payloads for ISRU technology demonstration would serve as a technology readiness level (TRL) driver and a de-risking technology. Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) is the only small size ISRU demonstration payload currently flown and on Mars to demonstrate oxygen extraction from the Martian atmosphere. The regolith/soils present in smaller bodies are identified to be rich in minerals resources such as precious metals, volatiles, organic and non-organic materials that can be harnessed for the good of humankind. This PhD research work aimed to advance an initial CubeSat-like payload design to demonstrate an ISRU process on a C – type near-earth asteroid (NEA). The result of the literature review performed was, the project background was elaborated. From the trade-off studies carried out for the selection process of the potential destinations and the ISRU process, C-type NEA 162173 Ryugu JU3, and hydrometallurgical sulphuric acid leaching experiment on olivine minerals have emerged as the winners. System requirements are generated, and for the proposed CubeSat payload system architecture comprising of sample acquisition subsystem, reaction chamber subsystems, acid solution delivery and extraction subsystem, the electroplating/wining subsystem, and analytical subsystem, an initial overall payload system design was achieved. This project has been focused on the re-design and manufacturing of the reaction chamber subsystems and top- plate system, and the design and manufacture of the leaching and the liquid handling sub-system (LHS). The result of laboratory hydrometallurgical sulphuric acid leaching experiments carried out found the optimal condition to achieve higher metal extraction from the reaction mixture occurs at 5M H₂SO₄ acid concentration, 1:5 mineral to acid volume ratio (1g/5ml), and in a state of agitation. The inclusion of bromophenol blue (BPB) dye in the leaching experiment to eliminate the initial use of litmus paper, detect the loss of acid concentration by providing a real-time visual colour transition from yellow to blue, within the required acid pH range and would expect to be compatible with future flight implementation. Using the 5M H₂SO₄ acid concentration, the BPB dye solution was observed to degrade and change to colourless. Sourcing an alternative dye that is stable in 5M H₂SO₄ acid to mitigate against this looming challenge was suggested for future work. The payload system design together with the optimal leaching condition generated, informed the Breadboard (BB) payload prototype system design, component selection, and manufacture. A version of the Reaction Chamber Subsystem (RCS) oven implemented in a co- running CubeSat relevant payload design (ISRU water extraction), and based on the initial size and volume, appears to be suitable for this project. The RCS is manufactured from a material that is sulphuric acid-resistant and was re-designed to allow for interfacing to the LHS. The top plate implemented on CubeSat based ISRU water extraction project was adapted, re-designed, and manufactured from a material that is sulphuric acid-resistant to enable the accommodation of the LHS and the associated system that will ensure efficient interaction between acid solution and the collected olivine regolith. The LHS subsystem is comprised of valves, pumps, manifolds, reservoirs, tubing connectors, and fittings. These components are interconnected, and they interact to establish the LHS that will allow for efficient liquid handling in microgravity. The LHS is operated to deliver H₂SO₄acid solution from the reservoir into the RCS and the extraction of the leachate from the RCS respectively. In the conclusion, the manufactured BB payload system was operated to simulate hydrometallurgical leaching and aspects of liquid handling processes. The result indicates the usefulness of the process and its feasibility for CubeSat implementation. Additional tests need to be performed to further validate the BB payload system’s usefulness. Also, various future works are presented that will increase the technology readiness level of the design concept to further validate the usefulness of the ISRU BB payload system.
Access status: Open Access ,
Assessment of non-elliptic lift distributions on span-extended wing design
(Cranfield University, 2022-12) Bragado Aldana, Estela; Riaz, Atif; Whidborne, James F.
In the pursuit of reducing the environmental impact of aviation, novel aircraft concepts and technologies are receiving increased attention from researchers and manufacturers. Amongst the solutions expected to improve aerodynamic efficiency, aircraft with high aspect ratio wings are being regarded as a promising solution, despite the numerous hindrances derived from such a configuration. Furthermore, the current socio-economic prospect has exacerbated the need to address the multi-disciplinary nature of the conceptual design process, in which traditional methods are becoming less reliable for the modelling of the envisioned novel configurations and technologies. To address some of these challenges, an elegant analytical approach promising improvements in the aero-structural efficiency and flight dynamic characteristics of wings has gained the interest of researchers around the world. This design approach proposes to remove the fixed-span constraint and instead prescribe structural requirements. This yields a set of non-elliptic lift distributions with theoretically improved aero-structural efficiency and lateral-directional flight dynamic characteristics. However, conclusions on the actual benefits and practical implications of the application of this theory remain unsettled. This thesis investigates some of the research questions posed by such an approach applied to the conceptual design of high aspect ratio wings. To do so, it provides a multidisciplinary physics-based design environment that integrates in-house developed and existing computational models within a setbased design approach. This allows for the analysis of feasible solutions with regard to overall performance improvement whilst shedding light on the relevant trade-offs. The proposed design and analysis approach yields span-extended configurations for which aerodynamic efficiency is improved through span extension and the consequent growth in wing structural weight is reduced as a result of the applied non-elliptic spanloads. The presentation of alternative figures of merit to comparatively assess the performance of the designs provides further insight than the use of other traditional metrics such as the lift-to-drag ratio. This yields several span-extended configurations without penalties in performance, following the methodology and metrics employed in the proposed design and analysis process. Furthermore, the semi-analytical approach to proverse yaw enables to identify the unconventional behaviour of induced drag during aileron deflection on wings with the selected non-elliptic spanloads. Additionally, it highlights that attainment of these solutions are highly dependent on flight condition, aileron sizing and location within a given spanload, and the magnitude of deflection. Overall, this thesis contributes to a further insight on the aero-structural trade-offs and proverse yaw characteristics derived from the use of such a design approach. This can facilitate the identification of the determining contributors and compromises to be made at early stages of the design, amplifying the designer’s control over the design and decision-making processes, while delaying critical decisions and enhancing the optimisation process with more informed drivers.
Access status: Open Access ,
Switched reluctance motor actuating systems for multirotor air vehicles
(Cranfield University, 2022-05) Biczyski, Marcin; Whidborne, James F.; Luk, Patrick Chi-Kwong; Sehab, R.; Krebs, G.
Among the race to net zero emissions, new vehicle concepts are thriving. Multirotor air vehicles are popular for consumer-grade applications like sport or photography, but they are also considered to solve the challenges of Urban Air Mobility. By analysing the multirotor vehicles and their typical faults, the highest severity of faults is attributed to the actuating system, of which the central component is the electric motor. Comparing avail- able technologies, switched reluctance (SR) motors are deemed a promising solution due to their high degree of fault-tolerance, ruggedness, sustainability and the lack of permanent magnets. Therefore, this study presents a process of designing an SR motor actuating system for use in multirotor vehicle applications. The efforts are focused on achieving desired functionality and documenting technical challenges, rather than achieving an optimal design. A pre-study on multirotor vehicle sizing methodology based on databases of off-the- shelf components is presented. This is then expanded to cover systems with electric motors in general. Based on sizing specifications, a set of SR motors is optimised for a range of vehicle weights. One design (corresponding to 8 kg quadrotor vehicle) is chosen for further analysis and manufacture. A PI controller-based control solution is developed and implemented, along the model of the whole actuating system in a simulator. Simulated performance is compared with that of a reference BLDC motor actuating system. In addition, system behaviour is analysed in the presence of uncertainties and injected faults. Results are expressed in terms of Loss of Effectiveness (LOE) metric used for the development of fault-tolerant control. The SR motor actuating system is then verified to be of adequate performance and good fault-tolerance, especially against open circuit faults in one or two phases. However, the system was found to be susceptible to position sensing system failure. In a preliminary comparison with BLDC motor actuating systems, the designed system is comparable in terms of performance, advantageous in terms of fault-tolerance and of considerably higher weight, which is attributed to immaturity of the technology. Sources of the SR motor system advantages are identified as reluctance torque and separation of phases, and recommended for further study.
Access status: Open Access ,
Design space exploration of gas turbine based ship propulsion systems
(Cranfield University, 2021-12) Batra, Amit; Sampath, Suresh; Nikolaidis, Theoklis
The conceptual design of a ship propulsion system, developed during the early stages of the overall ship design process, has a very large impact on the overall design and performance of a ship. Gas turbines are often utilized for warship propulsion systems designed to fulfil requirements of high ship speed and power density. To achieve a high overall system-level efficiency, gas turbines are often used in combined architectures with diesel engines along with geared, electric or hybrid transmission systems driving multiple propulsors. The process for the development of the conceptual design for such ‘combined’ systems, designed to achieve multiple and often conflicting design objectives, is significantly more complex compared to that for systems where a single-engine drives a propulsor. A number of approaches are currently used in practice towards the conceptual design of a ship, ranging from manual ‘design lanes’ based iterative approaches, to computerized overall ‘ship as a system’ design synthesis approaches. Towards the conceptual design of the propulsion system, both these approaches pose their own limitations, wherein the approach of the manual iterative design process relies heavily on the preferences of experts and approximations based on past experience; while the ship design synthesis approach usually yields good results generally if the candidate propulsion architectures are based on existing designs. This research work proposes a model-based process for the design space exploration using a model-based ‘Techno-economic & Environmental Risk Assessment’ (TERA) approach. To undertake feasibility and performance analysis of the candidate propulsion system architectures, the process involves building performance models of the candidate propulsion system architectures at this very early stage the overall design process of the ship and utilizing the generated results as the basis of design related decisions. For undertaking the performance modelling of the multiple candidate propulsion system architectures, an agile modelling and simulation framework was considered essential that could handle the complexity of ‘combined’ propulsion plants. To achieve this, a component-based modelling software, ‘Poseidon +’, has been developed as a part of the present work which enables 0-D modelling of gas turbine engines as well as the entire propulsion system in the same framework. A key aspect of this work was the development of an algorithm that analyses the direction of the torque transmission across the complex transmission system of ‘combined’ plants, based solely on the based on the states of the engine and clutches. For undertaking TERA, a suite of ‘Multiple-Criteria Decision-Making’ (MCDM) methods were selected and applied to select a compromise solution from competing propulsion system architectures, using a combination of performance data generated from simulation of developed models, and comparative expert opinions-based metrics for information not available early in the ship design process. To execute the MCDM procedure, a methodology of deriving weights of the competing design criteria using a combination of hierarchal and network structure, considering the degree of relationships between the design criteria, has been demonstrated. The overall proposed approach for design space exploration of gas turbine based ‘combined’ ship propulsion systems has been demonstrated towards the conceptual design analysis of two notional ship designs. The results of the analysis show the effectiveness of the proposed procedure for design space exploration of ship propulsion systems.
Access status: Open Access ,
Techno-economic environmental and risk assessment for large container ship gas turbine combined cycle propulsion systems
(Cranfield University, 2023-03) Alzayedi, Abdulaziz; Pilidis, Pericles; Sampath, Suresh
In recent years, the International Maritime Organization’s (IMO) stringent regulations on air pollutants, which are associated with increased fuel costs, have encouraged researchers to develop fuels and technologies that are cleaner and more efficient than conventional propulsion systems. This study defines and describes a techno-economic environmental and risk assessment (TERA) method for assessing substitute fuels and technologies that could be utilised in the maritime sector to replace two-stroke diesel engines fuelled by heavy fuel oil (HFO). This study aimed to develop a TERA method for marine technologies and to improve Cranfield University’s ship resistance simulation code, “Poseidon”. The study examined conventional propulsion systems, such as two-diesel engines fuelled by marine diesel oil and gas and steam combined cycle fuelled by liquefied natural gas and marine diesel fuel. The characteristic cryogenic properties of liquefied natural gas were employed to improve the efficiency of the combined cycle gas turbine cycles. The study selection criteria were performance, emissions, weight, and investment costs, including installation, operation, and maintenance costs for advanced combined gas and steam turbine cycles and two-stroke diesel engine propulsion systems for large container ships. A risk assessment was conducted to evaluate the impacts of capital cost, fuel cost, hull fouling resistance, container shipment price, discount rate, and emission taxation on the economic analysis. The results indicated that enhanced LNG combined cycles were the most efficient. Their enhanced combined cycle efficiency was 11% higher than two-stroke diesel engine efficiency and they reduced nitrogen oxide and carbon dioxide emissions by 76.3% and 44.7%, respectively. Regarding the weight of the propulsion systems, the combined gas and steam turbine propulsion system was approximately 24.7% lighter than the diesel engine propulsion system. For the routes that were considered and compared to a two-stroke diesel engine fuelled by MDO, the simple, intercooler/reheat, and enhanced gas and steam combined cycles that were fuelled by LNG increased the net present value by 78.3%, 78.5%, and 76.4%, respectively, and the payback period was reduced by 38.8%, 38.9%, and 35%, respectively. Additionally, the IRR showed a low-risk investment with significant potential benefits of CCGT cycles fuelled with LNG. The discount rate, container price, capital cost, emissions tax, and fuel cost scenarios showed the highest impact on economic results compared with the other scenarios for all technologies. The TERA was performed for different routes to evaluate the benefits and disadvantages of installing combined cycles instead of two-stroke diesel engines.
Access status: Open Access ,
A framework for business cloud services (BCSS) in SMEs
(Cranfield University, 2022-09) Alsafi, Tariq; Fan, Ip-Shing; McLaughlin, Patrick
The Saudi economy is changing rapidly to move from depending on energy to one with a wide range of indigenous businesses. Successful Small and Medium Enterprises (SMEs) are important in this economic transformation. Many Saudi Arabia SMEs are adopting Cloud Based Enterprise IT Services as the option to grow and sustain due to its cost and agility. However, they are often confused by the large international Cloud Services suppliers and not all SME reap the right business value from their Cloud Services investments. This research aims to create an approach to assist Saudi SMEs based on a strong research understanding. A novel framework is created that takes into account of the different functions of different Business Cloud Services, the different business requirements of each SME and their existing capabilities and readiness. Rather than treating all Cloud Services as the same, the researcher differentiates into three types: Digitalisation, Packaged and Enterprise. The research relates the Technological Resources, Organisation Capabilities, Organisational Requirements and Business Benefits for each of the Cloud Service types and then integrate them into one cohesive framework. This research adopted a pragmatic paradigm. The conceptual framework is developed through literature, contextualised, and improved qualitatively through interviews with 17 experts and 54 practitioners. The model was quantitatively examined with 395 questionnaires. The framework was developed into a readiness assessment tool and validated with three Saudi SMEs, who value the approach as beneficial business advice. The framework contributes to the improved structural knowledge of Cloud Services adoption. The constructs add contextualised factors to understand the business considerations relevant to Saudi SMEs.
Access status: Open Access ,
Developing a framework to facilitate a radical innovation culture in mature manufacturing organisations
(Cranfield University, 2022-06) Alqarni, Nouf Mari; McLaughlin, Patrick
The main purpose of this project was to investigate the impact of organisational culture and leadership practices on radical innovation enhancement in mature manufacturing organisations. The project is intended to advance understating of the key role played by these factors in this vital sector. This study was exploratory and interpretative in nature, and a social constructivist approach using inductive design was found appropriate for achieving its major goals. A qualitative approach was adopted. The study seeks to provide data that will help address the research gap. This data was gathered using a combination of semi-structured interviews, focus groups, and observation. A theoretical framework was designed to address the research questions and objectives. The research data was collected through the use of in-depth focus interviews. Participants were recruited from 18 large mature manufacturing organisations. After 21 interviews, a saturation point was reached. The findings of the study presented a variety of factors in the domains of culture, values, and setting that were identified as significant in affecting leadership performance. The results of this study proposed a framework with recommended interventions to facilitate a culture of radical innovation in mature manufacturing organisations. The emerged themes of the study played a key role in developing this framework. The findings should make a major contribution to the field of leadership and radical innovation and the process of change management, by providing empirical data on the significance of leadership's crucial role in creating a culture of radical innovation in the mature manufacturing sector in general.

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