PUBLICATIONS

This work outlines a workflow for developing a reduced-order combustion-chamber model that enables rapid computation of performance and pollutant emissions for aircraft gas-turbine engine design proce…

This work outlines a workflow for developing a reduced-order combustion-chamber model that enables rapid computation of performance and pollutant emissions for aircraft gas-turbine engine design processes, including configurations operating with Sustainable Aviation Fuels (SAF). The method is based on a zero-dimensional Chemical Reaction Network (CRN), selected for its computational efficiency and calibrated using data from high-fidelity, time-averaged unsteady 3D Computational Fluid Dynamics (CFD) simulations of an academic Rich-Burn/Quick-Mix/Lean-Burn (RQL) combustor. The CRN employs parallel Perfectly Stirred Reactors (PSRs) to represent flow and mixture inhomogeneities in the primary zone (PZ), and Plug Flow Reactors (PFRs) to model the secondary (SZ) and dilution (DZ) zones A comparison with CFD results across four operating points (take-off, climb-out, approach, and idle) demonstrates showed very good agreement for CO2 emissions (relative deviation <1.3 %), acceptable agreement for NOx (mean relative deviation = 15.7 %), and a mean relative deviation of 70 % for CO. In contrast, predictions of unburned hydrocarbons (UHC) show neither quantitative nor qualitative agreement, with the CRN model generally underpredicting UHC emissions. Analysis of UHC evolution along the flame tube axis reveals a rapid decrease in UHC concentrations at the beginning of the PFRs in the secondary and dilution zones, driven by oxidation caused by the freshly introduced mixing and dilution air, respectively.

Strut-braced large aspect ratio wings (LARW) with distributed hybrid-electric propulsion (DHEP) show promise in reducing noise and emissions from aircraft. The adoption of these technologies will furt…

Strut-braced large aspect ratio wings (LARW) with distributed hybrid-electric propulsion (DHEP) show promise in reducing noise and emissions from aircraft. The adoption of these technologies will further aviation sustainability and will improve the quality of life of communities near to airports. Existing low-fidelity models used for optimizing these configurations often neglect crucial flow physics typical of such complex and unconventional configurations, limiting their accuracy. This work explores two methods to enhance prediction capabilities suitable for early design phases: correcting the prediction of an existing low-fidelity model using an error-based approach and developing a stand-alone reduced order model based on high-fidelity Reynolds-Averaged Navier-Stokes (RANS) simulations. An error-based model aims to correct outputs from the low-fidelity surrogate, while a pure high-fidelity surrogate is constructed using the same samples. This work aims at understanding if the behaviour of the error between low- and high-fidelity predictions will have less nonlinearity than the flow itself, allowing for a more efficient and more effective building of the reduced order model. Both methods are evaluated by predicting the performance of an untrained configuration within the training space to determine which approach more effectively predicts lift and drag coefficients.

Within the emergent electric aircraft market, Distributed Electric Propulsion (DEP) is a promising concept. It provides benefits in terms of aerodynamics and propulsive efficiency, noise reduction, an…

Within the emergent electric aircraft market, Distributed Electric Propulsion (DEP) is a promising concept. It provides benefits in terms of aerodynamics and propulsive efficiency, noise reduction, and vehicle control [1]. Some of the new aircraft concepts applying DEP have high aspect ratio wings for improved efficiency. The light structure, in conjunction with the large propellers and motors mass and inertia, results in an enhanced structural flexibility of the wing, which can lead to an interaction between elastic deformations and rigid body flight dynamics that favors aeroelastic instabilities. This interaction may in turn be intensified by the gyroscopic effects induced by the propellers rotation, and the propellers aerodynamics.

This study presents a numerical investigation into the aerodynamic and aeroacousticcharacteristics of a 5-bladed propeller installed upstream of a symmetric wing in forwardflight. The research aims to…

This study presents a numerical investigation into the aerodynamic and aeroacousticcharacteristics of a 5-bladed propeller installed upstream of a symmetric wing in forwardflight. The research aims to assess near-field flow interactions and predict far-field noise levels,using two different approaches: a Lattice-Boltzmann-Method based solver implementedin the software PowerFLOW®, in conjunction with the Ffowcs-Williams and Hawkingsacoustic analogy, and a recently developed mid-fidelity fast and non-empirical approach,realized as a hybrid Reynolds Averaged Navier Stokes - Computational Aeroacousticsmethod, based on rotating line-distributed propeller sources. The computational setupemulates a typical operational condition, enabling detailed examination of how the upstreampropeller’s wake impacts the aeroacoustic profile of the wing-propeller configuration. Thiswork provides insights into tonal and broadband noise contributions and highlights tonalnoise amplification at blade passing frequencies due to the propeller-wing interaction.Further analysis will focus on the flow field characteristics, which are anticipated to revealinteractions between wake turbulence and wing surface, leading to complex noise patternsthat could be mitigated in future design optimizations. Upon completion, this study willextend the understanding of installation effects on noise generation in propeller-wingconfigurations, with the ultimate aim of guiding more efficient aeroacoustic designs foradvanced applications.

This study aims to experimentally and numerically investigate and compare the aerodynamic and aeroacoustic characteristics of four leading-edge mounted Distributed Electric Propulsion (DEP) configurat…

This study aims to experimentally and numerically investigate and compare the aerodynamic and aeroacoustic characteristics of four leading-edge mounted Distributed Electric Propulsion (DEP) configurations under different angles of attack. The aerodynamic performance of individual propeller positions and wings is studied and compared experimentally. Numerical simulations using Vortex Particle Method (VPM) are performed to compare with the experimental results and provide aeroacoustic analysis of different configurations. The test rigs are designed and tested in the Wind Tunnel Laboratory at the University of Bristol. The baseline configuration is set as the 12-12-12 propeller DEP with three identical 12-inch propellers. The 12-12-15 and 15-12-12 configurations replace the outboard and inboard 12-inch propellers with a 15-inch propeller, respectively. The fourth 12-12 configuration includes only two 12-inch propellers mounted at the leading edge of the same wing. The thrust of all configurations is matched to be the same as the baseline configuration. The results indicate that for all three-propeller configurations, the mid propeller produces slightly less thrust than the other two propellers, and the higher the propeller rotational speeds and angles of attack, the larger the difference. The torque required to drive the 15-inch propellers is considerably higher than the 12-inch propellers. The efficiency of the 15-inch propeller is higher than that of the 12-inch propeller under most thrust settings. Wing performance comparisons show that the 12-12 configuration performs the worst among all configurations in wing lift-to-drag ratio at two different propeller rotational speeds. At lower propeller rotational speeds, the baseline configuration yields better lift-to-drag ratio of the wing, while the 12-12-15 configuration takes over at higher propeller rotational speeds. Numerical aerodynamic results illustrate good agreement on thrust predictions, whereas torque predictions can vary significantly with the propeller positions on the wing. Aeroacoustic simulations suggest the 12-12 configuration has around 7 dB higher noise emission than all three-propeller configurations for the 1 st BPF, whereas only slight differences are observed between the three-propeller configurations.

This study aims to experimentally and numerically investigate and compare the aerodynamic performance of two triple-propulsor leading-edge mounted Distributed Electric Propulsion (DEP) configuration. …

This study aims to experimentally and numerically investigate and compare the aerodynamic performance of two triple-propulsor leading-edge mounted Distributed Electric Propulsion (DEP) configuration. The experiments are conducted in the Wind Tunnel Facilities at the University of Bristol. Propeller performance is examined experimentally against their positions on the wing at different inflow speeds and wing angles of attack (AoA). Numerical Vortex Particle Method (VPM) simulations are carried out to compare with the experimental aerodynamic results, and provide an exploratory noise comparison between the configurations. The DEP configurations involved in the current work are three 12-inch (the 12-12-12 configuration) and three 15-inch (the 15-15- 15 configuration) propellers. Aerodynamic measurements for the propellers and the overall wing are examined and analysed at inflow speeds of 10 and 20m/s. The 15-15-15 configuration is operating at lower propeller rotational speeds to match overall thrust to be the same as of the 12-12-12 configuration. The aerodynamic measurements indicate that mid propeller produces less thrust than adjacent propellers while having comparable torque, and this difference becomes more significant as propeller rotational speeds and wing AoA increase. For the 12-12-12 configuration, the propeller performance is less sensitive to the change of angle of attacks at 10m/s, whereas a noticeable increment in thrust is captured for the inboard propeller for the 15-15-15 configuration as AoA increases. Wing performance comparison indicates that the 15-15-15 wing has slight liftto-drag ratio improvements at low angles of attack, whereas the 12-12-12 configuration is marginally more favourable at high angles of attack. Numerical simulations show good agreement on propeller thrust predictions, whereas torque predictions significantly vary across different positions on the wing. The noise results indicate that the 15-15-15 configuration has a lower tonal noise emission than the 12-12-12 configuration at 1st Blade Passing Frequency (BPF) when producing the same thrust on the wing. The noise results indicate that the 15-15-15 configuration has a lower tonal noise emission than the 12-12-12 configuration at 1st Blade Passing Frequency (BPF) when producing the same thrust on the wing.

Hybrid-electric aircraft offer a promising pathway for reducing aviation emissions, but integrating novel powerplant components and their mission-level control presentssignificant design challenges. T…

Hybrid-electric aircraft offer a promising pathway for reducing aviation emissions, but integrating novel powerplant components and their mission-level control presentssignificant design challenges. This study employs a GEMSEO-based multidisciplinary optimization framework, to perform comprehensive sizing and optimization of the INDIGO aircraft—characterized by a high aspect ratio wing and distributed hybrid-electric propulsion optimized for reduced landing and takeoff (LTO) impact. The research evaluates optimization strategies across three scenarios: (1) single trajectory analysis, (2) multiple trajectories with a common control strategy, and (3) multiple trajectories with missionspecific control strategies. Results highlight the critical importance of multi-point analysis for achieving robust and reliable aircraft design. Although mission-specific control strategies provided more optimal outcomes, they also increased mission planning complexity. Furthermore, the study examines aircraft performance under five distinct failure scenarios, offering insights into the resilience and adaptability of hybrid-electric propulsion architectures. These findings contribute to a deeper understanding of optimization methodologiesfor emerging hybrid-electric aircraft configurations.

The current commitment towards aviation climate neutrality and decarbonisation is boosting research programmes on disruptive aircraft configurations featuring sustainable powertrains and fuel-efficien…

The current commitment towards aviation climate neutrality and decarbonisation is boosting research programmes on disruptive aircraft configurations featuring sustainable powertrains and fuel-efficient airframes. This trend is pushing the design towards high-aspect-ratio wings made of lightweight structures housing distributed propulsion systems. Airframe preliminary sizing and mass estimation of non-conventional configurations, if performed using legacy methodologies based on experience, gathered with traditional configurations may result in non-optimised and non-viable designs. Therefore, a physics-based optimisation approach may allow more accurate sizing and airframe mass estimation. The methodology suggested in this paper is based on the automatic generation of a global finite element model to estimate the weight and determine a feasible material distribution for the wing box structure of a strut-braced wing configuration by means of size optimisation. Composite materials with defined stacking sequences were assigned to the wing components and structural weight minimised with the aim of offsetting the weight penalties associated with this non-conventional aircraft configuration. Preliminary results suggest that the composite strut-braced wing could achieve a weight reduction of up to 44% compared to a composite cantilever wing with equal aspect ratio of 20. The actual weight reduction is thought to be lower due to potential overestimation of the cantilever configuration.

The increase in air traffic and its environmental impact necessitates an assessment of the potential health risks posed by aircraft pollutants to the civil population residing near airports. Wingtip v…

The increase in air traffic and its environmental impact necessitates an assessment of the potential health risks posed by aircraft pollutants to the civil population residing near airports. Wingtip vortices, one of the most prominent wake structures, play a crucial role in the dispersion of pollutants generated by aircraft. These vortices can persist for several minutes and travel hundreds of meters before decaying.Simultaneously, the growing need to reduce pollutant emissions and noise has driven the exploration of innovative technologies such as Distributed Hybrid Electric Propulsion (DHEP) systems and Large Aspect Ratio Wings (LARW). Within this context, the European INDIGO project—a consortium of ten research and scientific institutions—aims to investigate the application of these technologies in mid-range aircraft operations and assess their impact on airport vicinities.The complexity of pollutant dispersion, combined with the limited available data —particularly when applying DHEP and LARW technologies— necessitates the use of Computational Fluid Dynamics (CFD) as a fundamental tool. However, accurately modeling vortical structures presents significant challenges due to the high computational demands. These arise from the large domain sizes required to predict wakes and the broad range of spatial and temporal scales necessary to capture the various phasesof vortex decay. Furthermore, the method used to generate these vortices is a critical component of the modeling strategy, as it can influence subsequent wake dynamics and ultimately affect the accuracy of pollutant dispersion predictions in the near field of the aircraft. Among the available methods in the literature, the vortex sheet method—where the reactions of lift and drag forces on the air are imposed—stands out for its accuracy and its ability to model all stages of vortex evolution, includingthe vortex roll-up process. The objective of this study is twofold: first, to validate the simulation results of vortex evolution using a reference aircraft configuration for which numerical data is available, and second, to extend this methodology to analyze pollutant dispersion for the initial INDIGO aircraft design (without propellers)-incorporating LARW design-, using the vortex method. The aerodynamic simulations are performed within the framework of large-eddy simulations considering real force distributions and transporting a generic scalar as a surrogate of chemical pollutant.