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Item Metadata only Co-located offshore wind–wave energy systems: Can motion suppression and reliable power generation be achieved simultaneously?(Elsevier BV, 2023) Meng, F.; Sergiienko, N.; Ding, B.; Zhou, B.; Silva, L.S.P.D.; Cazzolato, B.; Li, Y.Floating offshore wind turbines (FOWTs) present a cost-competitive advantage over their fixed-bottom counterparts, but also have technical challenges of achieving the desired stability and power reliability of the wind turbine. It is believed that co-locating of wave energy converters (WECs) and a FOWT can be the solution to these challenges. However, as the power generation of WECs is strongly associated with their hydrodynamic response, their addition tends to have a detrimental effect on the FOWT’s performance. To address this challenge, this paper proposes a framework for combining a FOWT with a small wave array that will make it possible to simultaneously achieve a reliable overall power production, and minimise the motion of a floating platform. It is done by properly controlling the hydrodynamic coupling between FOWT and WEC via a model predictive control approach. The results demonstrate that this novel approach manages to achieve platform stability and power reliability simultaneously, although it might require to collaborate with an aerodynamic control at high wind speeds. This work can be used as a guidance for operation of co-located wind–wave power systems.Item Metadata only Design considerations for a three-tethered point absorber wave energy converter with nonlinear coupling between hydrodynamic modes(Elsevier BV, 2022) Tran, N.; Sergiienko, N.Y.; Cazzolato, B.S.; Ghayesh, M.H.; Arjomandi, M.Multi-mode Wave Energy Converters (WECs) are designed to harvest energy simultaneously from multiple hydrodynamic modes, thereby maximising power absorption. The behaviour of each mode must be carefully considered, given that hydrodynamic and geometric coupling between modes can lead to severe reductions in power if improperly designed. This study aims to investigate how the design of a planar three-tethered WEC can be used to tune the surge, heave and pitch hydrodynamic modes to achieve maximum power absorption. The effect of various tether arrangement and mass distribution design parameters on the performance of a WEC subjected to both geometric and hydrodynamic nonlinearities was investigated. Results indicated that, to absorb the most power in regular waves, the tether configuration should be adjusted such that the surge and heave dominant rigid body modes are resonant with the incident wave. Geometric nonlinearities associated with the tether arrangement were found to cause sub-harmonic excitations which severely compromised device performance, with further reductions in power when nonlinear hydrodynamics were considered. In irregular waves, the optimal design became more strongly driven by performance in surge. Overall, maximum power was achieved when all three tethers were attached close to one another on the bottom of the buoy.Item Open Access The effect of blade depth ratio on the performance of in-stream water wheels(Elsevier, 2023) Brandon-Toole, M.; Birzer, C.; Kelso, R.The power characteristics of an in-stream water wheel were measured experimentally to explore the influence of the blade depth ratio. The blade depth ratio has a significant effect on the performance of in-stream water wheels, but its influence has been overlooked throughout the literature. It was determined that the blade depth ratio has a greater impact on the power production than the number of blades at all tip-speed ratios. However, the variation between the maximum and minimum available power is greater at high blade depth ratios, so it is important to understand the relationship between the blade depth ratio and tip-speed ratio. Analysis of velocity triangles determined that at the inlet and outlet, the turbine blade contributes negatively to net torque. This effect is increased at higher blade depth ratios. It was also determined that the peak dry coefficient of power is linearly proportional to the blade submergence ratio, which is a measure of the total submerged blade area. This investigation progresses research in this area by highlighting an overlooked parameter and experimentally determining its influence on power characteristics.Item Open Access A Theoretical Review of Rotating Detonation Engines(IntechOpen, 2021) Shaw, I.J.; Kildare, J.A.C.; Evans, M.J.; Chinnici, A.; Sparks, C.; Rubaiyat, S.N.H.; Chin, R.C.; Medwell, P.R.; Rao, S.P.Rotating detonation engines are a novel device for generating thrust from combustion, in a highly efficient, yet mechanically simple form. This chapter presents a detailed literature review of rotating detonation engines. Particular focus is placed on the theoretical aspects and the fundamental operating principles of these engines. The review covers both experimental and computational studies, in order to identify gaps in current understanding. This will allow the identification of future work that is required to further develop rotating detonation engines.Item Open Access Vibrations of axially travelling CNT reinforced beams with clamped-clamped boundary condition and an elastic support(Elsevier BV, 2023) Sibtain, M.; Smith, S.; Yeganehmehr, A.; Ong, O.Z.S.; Ghayesh, M.H.Vibrational analysis in engineering systems of axially travelling beams has attracted noticeable attention due to the many applications, such as in robotic manipulators, cable tramways, textile fibres, and in general when there is the axial mass transport of a continuous structure. This article studies the vibrational response of axially-travelling, functionally-graded, carbon nanotube-(CNT)-reinforced beam structures, by investigating linear gyroscopic aspects, such as Argand diagrams. The distribution of CNT fibres is assumed to vary along the thickness of the beam. The Hamilton principle is employed to obtain the coupled axial and transverse behaviour of the beam, subjected to clamped-clamped boundary condition and additionally supported by a spring. These equations of motion are then solved using the modal decomposition technique for the Coriolis-dependent axial and transverse frequencies. For verification, the results are compared to the simplified case in the literature for CNT strengthened beams with zero axial velocity, the dynamics of axially travelling beams, studies of the clamped-clamped boundary condition, and the effects on the Argand diagrams, which have been performed. The Argand diagrams are plotted to examine the effects of varying axial speed on the different linear characteristics of vibration. Variation of the volume fraction of the CNT and the spring support, has also been considered, to understand its effects on the vibration characteristics. Results produced in this article are important in assisting in the future design of engineering devices involving axially travelling systems.Item Metadata only TiN versus TiSiN coatings in indentation, scratch and wear setting(Elsevier BV, 2021) Akhter, R.; Zhou, Z.; Xie, Z.; Munroe, P.The indentation response, scratch behaviour and wear performance of binary TiN and ternary TiSiN coatings under a variety of loading conditions were comparatively studied. The coatings were fabricated onto M42 steel substrates via closed field unbalanced magnetron sputtering ion plating. A maximum hardness value of ~40 GPa was obtained for one of the TiSiN coatings as compared to ~28 GPa for TiN. This was attributed to the nanocomposite structure, grain refinement, solid solution hardening and the higher compressive residual stress in the ternary coatings. The damage resistance of both the TiN and TiSiN coatings under indentation loading was governed by the dampening effects of sliding or shearing of the columnar grains along the grain boundaries coupled with the coatings’ respective mechanical characteristics. Improved scratch adhesion properties (i.e., higher LC1, LC2 and CPR values) were also observed for the TiSiN coatings that were underlain by their superior mechanical properties along with the graded structure, promoting the capacity to resist crack formation and delamination. Lower wear rates for the TiSiN coatings during dry sliding were found to be consistent with their higher H/Er, H3 /Er 2 and We values.Item Metadata only Dynamics of size-dependent multilayered shear deformable microbeams with axially functionally graded core and non-uniform mass supported by an intermediate elastic support(Elsevier, 2023) Sibtain, M.; Yee, K.; Ong, O.Z.S.; Ghayesh, M.H.; Amabili, M.The current study investigates the coupled dynamics of a size-dependent third-order shear deformable multilayered microbeam with an axially functionally graded core, a non-uniform mass distribution (mass imperfection) and an intermediate elastic support. A power-law function is used to model the material properties in the longitudinal direction of the core. The equations of motion are obtained by formulating the energies of the system while employing the modified couple stress theory to include miniature size effects within the multilayered microbeam structure. Hamilton's principle and the modal decomposition method are utilised to derive and solve the coupled motion equations. The equations of motion are first verified against a former work on a simplified microbeam system, while the numerical results are validated by comparison to those of a simplified functionally graded in axial direction obtained by finite element macrobeam simulation. It was concluded that increasing either the power term constant of the material grading or the value of the localized mass imperfection (when ) causes the first and second transverse and axial natural frequencies of the three-layered microbeam to decrease, whereas increasing the length-scale parameter causes the natural frequencies of transverse modes to increase, demonstrating the size-dependent effects of the three-layered microbeam.Item Open Access A numerical sensitivity study -The effectiveness of RFID-based ore tracking through a simulated coarse ore stockpile and the impacts of key process variables(Elsevier BV, 2023) Chen, J.; Lu, T.F.; Peukert, D.; Dowd, P.The ability to understand ore characteristics in real-time during mining processes is vital for ensuring product quality control. However, it is challenging to continuously track ore flow from the mine to the mill due to the blending of ore batches, especially within stockpiles. This paper presents a numerical study of copper ore tracking through a coarse ore stockpile. A discrete element model of a 3D stockpile was created using the EDEM software to evaluate the effectiveness of using RFID tags for ore tracking. To identify the primary variables and their effect on ore transport and tracking through the stockpile, a sensitivity study was conducted to investigate a range of process variables, such as ore size distribution, ore size range, RFID tag size, wall friction, the trajectory of charging particles and stockpile charging methods. The results show that the stockpile model is not sensitive to variables such as the ore size distribution, ore size range and RFID tag size, while wall friction, stockpile feed belt speed, segregation in the ore flow region and contact model have a significant effect on ore blending within the stockpile. It was found that the overall performance of RFID-based ore tracking through the stockpile is poor. For cases with only one or a few tags per ore batch the order in which the tags are read did not provide a good representation of the ore distribution for most scenarios This sensitivity study provides insights into new tracking strategies given the poor performance of RFID tracking shown by the simulation study.Item Restricted Reconstructing temperature fields from OH distribution and soot volume fraction in turbulent flames using an artificial neural network(Elsevier, 2024) Nie, X.; Zhang, W.; Dong, X.; Medwell, P.R.; Nathan, G.J.; Sun, Z.We present a methodology based on artificial neural networks for reconstructing flame temperature fields from planar distributions of hydroxyl (OH) radicals and soot volume fraction in turbulent jet flames. A convolutional neural network was trained using planar images of flame temperature, soot volume fraction and OH simultaneously recorded with laser-based experimental methods. Then, the capacity and accuracy of the neural network on reconstructing flame temperatures were assessed for the flame conditions not only within the training domain but also out of it. The results showed that the supervised neural network can reconstruct instantaneous temperature fields to within ± 60 K for the flame conditions within the training domain, and to within ± 150 K for the flame conditions outside of the training domain. Probability density functions (PDF) of reconstructed temperature and the joint PDFs with OH signals and soot volume fractions also show good statistical agreement with experiments. This work has application in extending measurement techniques into regimes that are presently difficult to achieve, such as by obtaining the training data for temperature with established low-speed imaging methods and using the neural network method to predict temperature from high-speed imaging of the other two scalars.Item Open Access Establishing the acute physiological and sleep disruption characteristics of wind farm versus road traffic noise disturbances in sleep: a randomized controlled trial protocol(Oxford University Press (OUP), 2023) Micic, G.; Zajamsek, B.; Lechat, B.; Hansen, K.; Scott, H.; Toson, B.; Liebich, T.; Dunbar, C.; Nguyen, D.P.; Decup, F.; Vakulin, A.; Lovato, N.; Lack, L.; Hansen, C.; Bruck, D.; Chai-Coetzer, C.L.; Mercer, J.; Doolan, C.; Catcheside, P.Study Objectives: Despite the global expansion of wind farms, effects of wind farm noise (WFN) on sleep remain poorly understood. This protocol details a randomized controlled trial designed to compare the sleep disruption characteristics of WFN versus road traffic noise (RTN). Methods: This study was a prospective, seven night within-subjects randomized controlled in-laboratory polysomnography-based trial. Four groups of adults were recruited from; <10 km away from a wind farm, including those with, and another group without, noise-related complaints; an urban RTN exposed group; and a group from a quiet rural area. Following an acclimation night, participants were exposed, in random order, to two separate nights with 20-s or 3-min duration WFN and RTN noise samples reproduced at multiple sound pressure levels during established sleep. Four other nights tested for continuous WFN exposure during wake and/ or sleep on sleep outcomes. Results: The primary analyses will assess changes in electroencephalography (EEG) assessed as micro-arousals (EEG shifts to faster frequencies lasting 3–15 s) and awakenings (>15 s events) from sleep by each noise type with acute (20-s) and more sustained (3-min) noise exposures. Secondary analyses will compare dose–response effects of sound pressure level and noise type on EEG K-complex probabilities and quantitative EEG measures, and cardiovascular activation responses. Group effects, self-reported noise sensitivity, and wake versus sleep noise exposure effects will also be examined. Conclusions: This study will help to clarify if wind farm noise has different sleep disruption characteristics compared to road traffic noise.Item Open Access POD analysis of the turbulent boundary layer flow downstream of miniature vortex generators(Elsevier BV, 2023) Chan, C.I.; Chin, R.C.In this study we investigate the influence of an array of miniature vortex generators (MVGs) in a zero-pressuregradient turbulent boundary layer (ZPG TBL) by means of a large-eddy simulation of rectangular MVGs in a spatially evolving moderate Reynolds number ZPG TBL up to 𝑅𝑒𝜏 = 1350. The MVG array consists of pairs of rectangular blades arranged in spanwise oriented arrays in the flow. The turbulent intensities and streamwise inclination angles related to the large streamwise extent high-momentum regions (HMRs) and low-momentum regions (LMRs) induced by the MVGs are presented. The instantaneous velocity fluctuation is decomposed into a turbulent velocity component and a spatial velocity component based on the triple velocity decomposition, where the spatial velocity component represents a spatial variation of the time-averaged flow induced by the MVGs. The streamwise turbulent velocity fluctuation associated with the HMRs and the LMRs is further investigated using proper orthogonal decomposition (POD), where we further examine a reduced-order reconstruction of the HMRs and the LMRs, using two-dimensional data. POD has also been used to determine the streamwise inclination angle of wall-attached structures in the HMRs and the LMRs. An examination of the streamwise inclination angle associated with the POD modes has been performed. Results suggest that the streamwise inclination angle of higher energy POD modes may be related to that of the relatively large wallattached structures reported in the literature. In addition, if the lower energy POD modes are also retained, the value of the streamwise inclination angle tends to approach the value of mean streamwise inclination angle of wall-attached structures. The results suggest that the decreasing trend in streamwise inclination angle may be related to the contributions of the small-scale wall-attached motions.Item Open Access The Structural Response of the Human Head to a Vertex Impact(Springer (part of Springer Nature), 2023) Thompson-Bagshaw, D.W.; Quarrington, R.D.; Dwyer, A.M.; Jones, N.R.; Jones, C.F.In experimental models of cervical spine trauma caused by near-vertex head-first impact, a surrogate headform may be substituted for the cadaveric head. To inform headform design and to verify that such substitution is valid, the force-deformation response of the human head with boundary conditions relevant to cervical spine head-first impact models is required. There are currently no biomechanics data that characterize the force-deformation response of the isolated head supported at the occiput and compressed at the vertex by a flat impactor. The effect of impact velocity (1, 2 or 3 m/s) on the response of human heads (N = 22) subjected to vertex impacts, while supported by a rigid occipital mount, was investigated. 1 and 2 m/s impacts elicited force-deformation responses with two linear regions, while 3 m/s impacts resulted in a single linear region and skull base ring fractures. Peak force and stiffness increased from 1 to 2 and 3 m/s. Deformation at peak force and absorbed energy increased from 1 to 2 m/s, but decreased from 2 to 3 m/s. The data reported herein enhances the limited knowledge on the human head's response to a vertex impact, which may allow for validation of surrogate head models in this loading scenario.Item Open Access Analysis of crack closure and wake of plasticity with the distributed dislocation technique(Elsevier, 2023) Vidler, J.; Kotousov, A.; Ng, C.T.A new method for the analysis of plasticity-induced closure of finite cracks is developed based on the distributed dislocation technique. The method is applied to analyse closure and opening processes for an embedded fatigue crack propagating under constant amplitude cyclic loading. The obtained solution and presented results can serve as a benchmark for numerical procedures utilising the same yield-strip methodology. Comparison with past numerical studies reveals similar trends, though there are some differences in the crack tip opening values, particularly for low and negative R-ratios. The latter may indicate the need for a better approach to the discretisation of the contact, direct and reverse plasticity zones in the numerical procedures which utilise the same methodology. The developed method is general, and it can be adapted to evaluate the crack tip opening stress for other crack geometries and loading conditions.Item Open Access The reactor-based perspective on finite-rate chemistry in turbulent reacting flows: A review from traditional to low-emission combustion(Elsevier, 2023) Péquin, A.; Evans, M.J.; Chinnici, A.; Medwell, P.R.; Parente, A.In flames, turbulence can either limit or enhance combustion efficiency by means of strain and mixing. The interactions between turbulent motions and chemistry are crucial to the behaviour of combustion processes. In particular, it is essential to correctly capture non-equilibrium phenomena such as localised ignition and extinction to faithfully predict pollutant formation. Reactor-based combustion models — such as the Eddy Dissipation Concept (EDC) or Partially Stirred Reactor (PaSR) — may account for turbulence-chemistry interactions at an affordable computational cost by calculating combustion rates relying upon canonical reactors of small fluid size and timescale. The models may include multiscale mixing, detailed chemical kinetic schemes and high-fidelity multispecies diffusion treatments. Although originally derived for conventional, highly turbulent combustion, numerous recent efforts have sought to generalise beyond simple empirical correlations using more sophisticated relationships. More recent models incorporate the estimation of scales based on local variables such as turbulent Reynolds and Damköhler numbers, phenomenological descriptions of turbulence based on fractal theory or specific events such as extinction. These modifications significantly broaden the effective range of operating conditions and combustion regimes these models can be applied to, as in the particular case of Moderate or Intense Low-oxygen Dilution (MILD) combustion. MILD combustion is renown for its ability to deliver appealing features such as abated pollutant emissions, elevated thermal efficiency and fuel flexibility. This review describes the development and current state-of-the-art in finite-rate, reactor-based combustion approaches. Recently investigated model improvements and adaptations will be discussed, with specific focus on the MILD combustion regime. Finally, to bridge the gap between laboratory-scale canonical burners and industrial combustion systems, the current directions and the future outlook for development are discussed.Item Metadata only A numerical investigation of methane pyrolysis in a molten catalyst Bath–A single bubble approach(Elsevier BV, 2023) Mehrabian, N.; Seyfaee, A.; Nathan, G.J.; Jafarian, M.A dynamic one-dimensional numerical model of methane pyrolysis within a rising and pyrolysing bubble in a column of molten Ni0:27Bi0:73, as a molten catalyst, is presented. The model predicts both the behavior of the rising bubble in the column and the chemical reactions within it, accounting for any variations in bubble diameter and rising velocity, which have previously been assumed to be constant. The conservation equations of energy, mass and momentum are solved simultaneously using the implicit GausseSeidel numerical method. The model accounts for the main parameters contributing to the methane pyrolysis reaction. The reliability of the model was assessed by comparison with the available experimental data from the literature and a reasonable agreement was found. Considering the model assumptions, the results show that, for the assessed conditions, more than 97% of the overall conversion occurs at the interface of the bubble and the molten bath, while the reaction within the bubble contributes only <3% of the overall conversion. A sensitivity analysis was also undertaken to the variations in the bubble size, column height, molten bath temperature, pressure, gas composition and temperature. Calculations show that methane conversion is more sensitive to the molten bath temperature than the initial gas temperature. Furthermore, it decreases significantly with any increase in pressure. Also, at pressures of > 2 MPa, the equilibrium condition is achieved within the bottom one-third of the column for the assessed conditions.Item Metadata only The effect of oxygen concentration in the co-flow of laminar ethylene diffusion flames(Elsevier, 2020) Sun, Z.; Dally, B.; Alwahabi, Z.; Nathan, G.Abstract not availableItem Metadata only Statistical relationship between soot volume fraction, temperature, primary particle diameter and OH radicals along transects normal to the local reaction zone in a turbulent flame(Elsevier, 2021) Sun, Z.; Dally, B.; Alwahabi, Z.; Nathan, G.Abstract not availableItem Metadata only Pool boiling heat transfer to CuO-H₂O nanofluid on finned surfaces(Elsevier, 2020) Li, Z.; Sarafraz, M.M.; Mazinani, A.; Hayat, T.; Alsulami, H.; Goodarzi, M.Abstract not availableItem Open Access Paired-IRF Method for Detecting Leaks in Pipe Networks(American Society of Civil Engineers, 2020) Zeng, W.; Gong, J.; Simpson, A.R.; Cazzolato, B.S.; Zecchin, A.C.; Lambert, M.F.Abstract not availableItem Open Access Hydrogen addition to a commercial self-aspirating burner and assessment of a practical burner modification strategy to improve performance(Elsevier, 2024) Gee, A.J.; Proud, D.B.; Smith, N.; Chinnici, A.; Medwell, P.R.The ability for existing burners to operate safely and efficiently on hydrogen-blended fuels is a primary concern for the many industries looking to adopt hydrogen as an alternative fuel. This study investigates the efficacy of increasing fuel injector diameter as a simple modification strategy to extend the hydrogen-blending limits before flashback. The collateral effects of this modification are quantified with respect to a set of key performance criteria. The results show that the unmodified burner can sustain up to 50 vol% hydrogen addition before flashback. Increasing the fuel injector diameter reduces primary aeration, allowing for stable operation on up to 100% hydrogen. The flame length, visibility and radiant heat transfer properties are all increased as a result of the reduced air entrainment with a trade-off reported for NOx emissions, where, in addition to the effects of hydrogen, reducing air entrainment further increases NOx emissions.