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A Simple Phase Synchronization Algorithm for Aeroacoustics Studies of Multi Propeller system

2026-06-20T08:45:06Z

Title: A Simple Phase Synchronization Algorithm for Aeroacoustics Studies of Multi Propeller system Authors: Bhardwaj, M; Chong, TP; Chaitanya, P; Joseph, P Abstract: Phase synchronization between propellers is a critical factor influencing aerodynamic interactions and their noise generation in electric vertical take-off and landing (eVTOL) vehicles and unmanned aerial systems (UAS). While several studies have demonstrated the benefits of phase control of propellers for noise reduction purposes, practical methods for accurately identifying phase differences in experimental environments are complicated and remain limited. This paper introduces a phase detection and filtering algorithm utilizing Gaussian weighting technique to extract data corresponding to the required phase differences between two propellers. It also assists in decomposing the noise into different angular positions. The algorithm compares the timing signals from two tachometers and separates the target data according to the defined phase difference between the propellers. If both the flow and noise fields are measured simultaneously, both data can then be decomposed based on the defined phase difference and the angular position of the propellers. Validation results confirm the reliability of this method in separating the datasets into defined phase difference with good accuracy, facilitating the systematic analysis of tonal noise behavior in synchronized propeller configurations. Description: Data availability: Data will be made available on request.

Development of social sustainability assessment methods for solar thermal energy systems applied to industrial processes

2026-06-20T02:01:01Z

Title: Development of social sustainability assessment methods for solar thermal energy systems applied to industrial processes Authors: Zafar, Imaad Abstract: This thesis assessed the social sustainability of a newly developed Solar Thermal Energy (STE) system using the following methods. First, a Social Life Cycle Assessment (S-LCA) was conducted using Social Hotspot Database (SHDB) inventory data to assess social risks on employees involved in producing the system’s three components: Fresnel solar collectors (SunDial), the Phase Change Material (PCM) storage tank, and the Control Unit. Next, surveys involving 56 employees engaged in the technology’s Product Development phase were conducted to assess social impact in the following impact categories: Training Satisfaction (TS), Professional Development (PD), and Working Intensity (WI). Industrial and social acceptance of the technology was then assessed through surveys with 318 industries and 279 members of the public, capturing perceptions of the system’s adoption potential, greenhouse gas (GHG) reduction, and economic savings. Finally, a regression model was conducted to predict future trends in social impact and industrial acceptance over a 10-year timeframe, providing insights into long-term technological and financial improvements. Results of the S-LCA revealed substantial Health & Safety (H&S) risks for employees involved in the technology’s production, particularly in aluminium manufacturing of the PCM storage tank due to non-compliance with regional H&S policies. In the Product Development phase, positive impact was observed in PD and WI, whereas a negative impact score of -0.5 in TS revealed training provision gaps. Regression analysis identified strong correlations between social impact and influencing investments in Human Resource Management (HRM) including provision of training; PT (ρ = 0.54), employee engagement in R&D; EE, (ρ = 0.48), provision of professional development opportunities; PPD (ρ = 0.80), and task allocation; AT (ρ = 0.63), all statistically significant (p < 0.05). Next, surveys gauging the acceptance of worldwide industries showed strong results for the STE system’s technical compatibility (82%), costs (82%), and impact on standard compliance (87%), with highest scores reported by the Aerospace (92%), Metallic (89%), and Automotive (86%) industries. Acceptance was particularly strong among large companies (84%) and medium-sized companies (87%), whereas lower rates were observed for small (45%) and micro (37%) enterprises, largely due to the upfront costs of STE systems, which posed a greater financial burden for firms of this scale. Moreover, surveys involving the general public showed strong agreement with STE’s environmental benefits (86%) and willingness to consume products manufactured using STE’s clean energy goods (79%). Results of the future predictions showed that social impact on employees improved over the decade, as indicated by the probability of observing TS = 5 increased from 0.10 to 0.30 and TS = 4 from 0.35 to 0.60 due to annual investment in EE. Similarly, the probability of observing PD = 5 increased from 0.20 to 0.50 and WI = 4 from 0.25 to 0.50 from investment in PPD and AT, respectively. Industrial acceptance also marginally improved over the decade; most notably, AC = 5 rose from 0.44 to 0.52, and AC = 4 increased from 0.41 to 0.46. A large improvement was found amongst small and micro-sized companies as the probability of observing a high score rose 0.45 to 0.67 for small companies and 0.37 to 0.62 for micro-sized companies. The findings provide nuanced technological and monetary improvement measures to enhance the long-term sustainability and industrial relevance of newly developed STE systems. The findings of this thesis demonstrate the strong influence of targeted investments in workforce development, technological improvements, and financial support mechanisms on enhancing both social impact and industrial acceptance of STE systems over the decade. These thesis insights on influencing factors provide valuable implications for workforce managers, industrial stakeholders, and policymakers by offering practical guidance on forecasting, prioritising, and strategically allocating resources to maximise stakeholder satisfaction and support industrial adoption of current and future emerging STE deployments. Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London

Leading edge blowing: A targeted approach to reduce aerofoil noise

2026-06-19T02:01:14Z

Title: Leading edge blowing: A targeted approach to reduce aerofoil noise Authors: Bakrania, Yash Abstract: This thesis investigates steady leading-edge blowing as an active flow-control strategy for reducing aerofoil self-noise from a NACA 65(12)-10 aerofoil. The work considers three noise mechanisms: trailing-edge tonal noise, leading-edge broadband turbulence-interaction noise, and separation-stall noise. Far-field acoustic measurements are combined with hot-wire anemometry, surface-pressure measurements, and aerodynamic force measurements so that the acoustic response can be interpreted alongside the underlying flow physics. The first part of the study examines trailing-edge tonal noise. The results show that leading-edge blowing can strongly suppress the discrete tonal radiation associated with a suction-side laminar separation bubble and the aeroacoustic feedback loop it supports. Under the most effec-tive conditions, tonal levels are reduced by up to 20–25 dB. The main effect is not a large shift in tonal frequency, but a weakening of the organised instability and of the flow-acoustic coupling that sustains the tone. The second part addresses leading-edge broadband noise under both isotropic and anisotropic turbulent inflow conditions. Here, the effectiveness of the control is found to depend strongly on the incoming turbulence, particularly its length scale, anisotropy, and spatial coherence. When the actuation is suitably matched to the inflow, measurable broadband reductions are achieved. These reductions are linked to a weakening of spanwise coherence and to a shortening of the effective interaction length at the leading edge, showing that the control acts by modifying the structure of the incoming disturbances before they are scattered into sound. The final part of the thesis considers separation-stall noise at high incidence. In this regime, leading-edge blowing delays the onset of stall-related separation by up to about 3.7◦ and reduces the associated low-frequency acoustic radiation by up to 5 dB. The measurements show that the blowing modifies the separated-flow topology and weakens the large-scale unsteady structures that dominate the noise generation process. Overall, the thesis shows that steady leading-edge blowing is more than a case-specific method of reducing noise. It acts as a targeted control strategy that can influence several aerofoil self-noise mechanisms through changes to the near-field flow structure. The central finding is that noise reduction is achieved by weakening the coherence and organisation of the source regions that radiate most efficiently. This provides a basis for the future design of quieter aerofoils and blade sections using tunable leading-edge actuation in applications such as aircraft, turbomachinery, propellers, and wind turbines. Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London

Microgrid techno-economic optimisation for benchmarking operational net-zero metrics in a hotel typology

2026-06-19T02:01:13Z

Title: Microgrid techno-economic optimisation for benchmarking operational net-zero metrics in a hotel typology Authors: Shinku, Benedict Tertsea Abstract: Hotels account for about 1.5% of global energy-related emissions and an estimated 0.6% of UK energy demand in the operational phase. Hence, they have significant potential to contribute to sustainability and Net Zero through reduction in energy and carbon intensity. In the UK, the ongoing reform of the Energy Certificate System to include headline metrics suitable for monitoring energy efficiency, and the introduction of the UK Net Zero Carbon Buildings Standard (UKNZCBS) are beneficial initiatives for the achievement of net zero in hotels. This work applied a quantitative case study research design framed on a three-pronged methodology to evaluate feasibility of operational net zero for a mid-range (3-star) non-resort hotel located in London, UK over a 28-year lifetime. A baseline dynamic simulation model of the hotel (with 2022 as base year) was developed in IESVE™ and calibrated against the measured power consumption, using ASHRAE-14 Guidelines. The calibration confirmed the model within the verification acceptance range (NMBE= 4.75%, CvRMSE = 12.6%). Additional models were developed from the calibrated model by application of 30 energy efficiency measures and future weather files under SSP2-4.5 scenarios. Evaluation of the energy and carbon performance of the models between the baseline year and 2050 showed that climate change resulted in a 15% and 230% reduction in EUI and emissions, respectively. The highest reduction in EUI (40%) over the corresponding period occurred from reduction of envelope U-values to conform with the “2025 UK Future Buildings Standard” (UKFBS), lighting retrofit from fluorescent to LED, and application of Adaptive Ventilation (AV) strategy, translated to 236% emissions reduction. The second part of the methodology entailed creation of a solar- PV generation model in HelioScope™ and in the third part, electrical and thermal loads from IESVE™ and the solar-PV generation HelioScope™ were coupled to a microgrid model in HOMER Pro™, with random day-to-day and timestep variability of 10% and 20%, respectively. The variabilities accounted for the sensitivities of the energy profile to uncertainties in weather, occupancy and operational schedule, service levels, and occupant energy behaviour. The microgrid model was simulated under existing and projected macroeconomic (medium GDP growth) conditions, reference energy and emissions forecasts, and sensitivity variables (expected inflation rate, grid carbon intensity and minimum renewable fraction). The least cost microgrid yielded an IRR (6.2%), ROI (4.1%), discounted payback (12 years) and energy cost savings of £109,698. The benchmark values of operational net zero metrics calculated from the least-cost microgrid model were: EUI of 256 kWh/m2 (EUIel = 105 kWh/m2, EUIth = 406 kWh/ m2), CEI (87 CO2/m2), ECI (29.48 £/m2). The solar-PV generation model for the case study gave: (40.1 kW capacity, 43.8 MWh annual production, 75.5% Performance Ratio, and 906 kWh/kWp specific yield). Comparison of the results to the limits and targets of operational net zero metrics in the UK Green Building Council (UKGBC) Paris Proof Methodology (PPM), UKNZCBS and Cornell Hotel Sustainability Benchmark Index (CHSBI) for fifty 3-star non-resort hotels located in London, UK. The computed EUI, CEI and ECI values were significantly-above the CHSBI benchmarks due to disproportionate thermal and electrical energy demand. The retrofit pathway with the highest EUI reduction did not lead to operational net zero in 2050 under the UKGBC-PPM, nor the UKNZCBS frameworks. In addition, the target 40 kWh/m2 of Gross Internal Area (GIA) for onsite renewable energy generation specified in the UKNZCBS was not met. Unlike the hotelspecific room-night normalised energy, carbon, and cost metrics such as kWh/roomnight, kgCO2e/room-night and RevPAR (Revenue per Available Room, the metrics in this study were floor-area normalised to align with the UK Building Regulations thereby easing regulatory oversight of hotel energy efficiency and decarbonisation. The methodology of this work is a novel contribution to the planning of energy efficiency and net zero projects, applicable to any building typology and the benchmark values of EUI, CEI and ECI are a useful addition to the body of evidence for operationalisation of the UKNZCBS. Regardless, the generalisability of the results is limited by the purposive sampling technique adopted to select the case study, and the application of deterministic safety margins to electrical and thermal loads in the microgrid model to account for uncertainties in weather, occupancy, and operational schedules. Hence, statistical sampling and detailed sensitivity and uncertainty analysis should be incorporated in future research to enhance the application of the results to energy efficiency and decarbonisation policy and project planning. Description: This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London