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A new body force-based modelling approach for centrifugal compressor post-stall aerodynamics
No full textCopyright © 2025 by Rolls-Royce plcA lower-order modelling approach is developed, whereby the compression system is modelled as an empty duct, with body force-fields imparting turning and losses to the flow. The flow-field solution is obtained transiently by solving the axisymmetric Euler equations with metal and aerodynamic blockage in the relative frame of reference. The solver is coupled with a fully custom body force model consisting of a base turning force, correction force and viscous force component. Anew blockage-mixing model is derived providing estimations for aerodynamic blockage as well as the associated mixing losses and change in flow direction. Separation losses are introduced via the turning force coupled with a shape function which allows adjustment of the reattachment position. The blockage-mixing and separation modelling methods are verified against 3D RANS data, providing consistently reliable predictions. The steady-state, reverse flow performance predictions at different speeds are compared against 3D RANS simulations, showing excellent agreement. Surge simulations are subsequently carried out using an 1D plenum model. As the experimental rig’s plenum details are not provided, the plenum volume is varied until the experimentally reported surge cycle frequency is achieved. Unsteady pressure measurements are compared against the experimental ones, showing excellent agreement in the entire range of the surge cycles. Flow-field contours at different time instances are in concert with the experimentally obtained DPIV measurements, accurately capturing the onset of stall in the vaned diffuser. The simulations indicate deep surge behaviour, confirming conjectures from the experimental report which could not eventually be confirmed during testing. The code constitutes the first successful, validated, through-flow approach, capable of predicting the post-stall, steady-state and transient aerodynamic performance in centrifugal compressors, while reducing the computational cost by at least one order of magnitude compared to conventional CFD modelling approaches.The authors would like to thank Rolls-Royce plc. for supporting this work.ASME Turbo Expo 2025: Turbomachinery Technical Conference and Expositio
Insights into the cavitation behavior of a boundary layer pump
No full textCopyright VC 2025 by Rolls-Royce plc.Several researchers in literature have claimed that boundary layer pumps have an increased resistance to cavitation because of the absence of blades. Their conclusion was obtained analytically by applying the simple assumption of uniform radial velocity at the entrance of all the channels. This study considers the effect of flow distribution between the channels and assesses the full 3D geometry of a boundary layer pump which was tested in an experimental campaign by Morris. The pump's flow field is obtained with steady-state multiphase 3D-RANS simulations in which the inlet total pressure is gradually reduced. For each inlet total pressure point, the vapor formation is examined, and hence the cavitation mechanisms are analyzed, and the head drop curve is obtained. Results show that the mass flow distribution in the channels is highly nonuniform, which heavily affects vapor formation areas. There is a 127% difference between the lowest and highest channel mass flow. Less mass flow is entering the channels closer to the entrance of the pump, because this requires the flow to turn almost 90 deg from the axial to the radial direction. The viscous forces accelerate less mass more easily, and this leads to up to 22% lower pressure values in the low flow channels. Therefore, vapor starts forming in these channels, and the further the net positive suction head (NPSH) reduces, it sequentially propagates to adjacent channels toward the back like a domino and expands its volume inside each gap.Cranfield University, Rolls-Royce plcJournal of Engineering for Gas Turbines and Powe
A space-based debris cataloguing system for the new space era
No full textOver the past decades, space activities have increased significantly, giving rise to a growing threat: space debris. Today, over 28,160 objects are tracked by the U.S. Space Surveillance Network, primarily those larger than 10 cm in low-Earth orbit (LEO). However, 100,000s of debris below this size remain largely untracked, despite being a major cause of missionending damage. Most Space Situational Awareness (SSA) systems can catalogue objects down to 10 cm, but conjunction assessments and collision avoidance manoeuvres only address less than 1% of the impact risk. Meanwhile, spacecraft remain vulnerable to catastrophic, undetected collisions with debris between 0.1 and 10 cm. Hence, mitigating existing risks is a critical priority for the space sector. The growing importance of SSA highlights the need to track centimetre-sized debris.
This paper presents a Phase 0 feasibility study of the Threat and Hazard Evaluation for Intelligent Awareness (THEIA) mission, a space-based system designed to address this observation gap. THEIA employs a dual-payload constellation of 12-unit CubeSats, with radar satellites performing initial orbit determination and optical satellites enabling precise orbit determination. The baseline configuration, consisting of 15 radar satellites and 108 optical satellites in complementary orbital planes, achieves approximately 26% catalogue completeness of 5–10 cm debris within five years. Although below the 80% target, the study demonstrates the technical feasibility of centimetre-class debris tracking within CubeSat constraints and confirms the potential for scalable small-satellite architectures.
The financial analysis, based on a discounted cash flow model, indicates strong economic viability with a positive net present value exceeding =C1 billion under hybrid funding assumptions. However, limitations remain in radar payload performance, constellation coverage, and dynamical modelling, which considered only simplified perturbations. Future
work should include higher-fidelity modelling, collision risk assessment for observer satellites, shielding and avoidance strategies, and the evaluation of larger platforms to increase radar performance and catalogue completeness. Overall, THEIA demonstrates that centimetre-class debris cataloguing is both technically and economically feasible,
providing a foundation for safer and more sustainable space operations.23rd IAA Symposium on Space Debris, Held at the 76th International Astronautical Congress (IAC 2025
Systematic study on the role of Mn, Si, and Fe on the corrosion resistance of Ni-based superalloys exposed to air, gaseous sulfur oxides and salts
Get PDFThis work investigates the effect of alloying elements Mn, Si, and Fe on the corrosion resistance of polycrystalline Ni-based superalloys, at 700 C in air and 300 vpm SO2 under 5 lg cm2 h salt coating. Oxide scale morphology and composition was investigated using SEM–EDX and APT, revealing Mn–Fe-enriched Co3O4 particles in the upper outward growing scale as well as Si-Fe-enriched clusters in NiO. Along the NiO–Co3O4 phase boundary, a tight network of Fe-decorated dislocations relieving stress between the lattices was identified through APT. In the inward growing scale, Si enrichment was observed in the form of oxides and sulfides, while no Mn was detected.This work was funded by Rolls-Royce plc. The LEAP used for this work is funded by EPSRC Grant No. EP/M022803/1.Metallurgical and Materials Transactions
Scalable and sustainable cellulose xerogels for high-capacity enrichment of per- and polyfluoroalkyl substances
Get PDFThe phase-out of long chain per- and polyfluoroalkyl substances (PFAS) has accelerated the adoption of alternative emerging PFAS, posing a dual pollution challenge with persistent long-chain residues and their substitutes unclear fate in water treatment. Herein, we develop a scalable and closed-loop strategy producing aminated cellulose xerogel (CNPK) for PFAS removal. CNPK demonstrates excellent mechanical strength (1.96 MPa) and superior PFAS adsorption capacities (3.26 g−1 HFPO-TrA, 1.82 g−1 PFOA, 2.14 g−1 HFPO-DA, 1.27 g−1 PFHxA, 1.02 g−1 PFBA and 1.01 g−1 PFPrA) at pH 3. Its ability to absorb several times its own weight of PFAS is orders of magnitude higher than that of traditional adsorbents. In multi-component systems, the enhanced kinetics and affinity for short/ultra-short chain PFAS facilitate their near-complete removal. This is due to the preferential capture of long chains that provide additional van der Waals (vdW) interactions to accelerate short/ultra-chain adsorption. After five consecutive cycles, CNPK still achieves removal rates of 82%-99% for six types of PFAS and can be dissolved and reproduced. The proof-of-concept filter column achieves over 95% removal for short/ultra-short chain PFAS. The life cycle assessment (LCA) highlights xerogels having lower carbon footprint (161.28–161.71 kg CO2eq kg−1 PFAS) compared to most carbon-based adsorbents. Overall, this xerogel strategy tackles the urgent PFAS contamination through high-capacity enrichment under the principles of the circular economy.This work was supported by the “Pioneer” and “Leading Goose” R&D Program of Zhejiang Province (2024C03112, 2024C03233).Water Researc
‘Greening’ the UK: a comparative study of heat pumps and hydrogen boilers in residential heating
Get PDFThis article belongs to the Special Issue Energy Transition: Interaction of Gas/Hydrogen and Electricity SystemsWith a key policy decision on the role of hydrogen boilers expected by 2026, the UK is at a strategic crossroads in implementing its Heat and Buildings Strategy. This study evaluates the relative advantages of hydrogen boilers and heat pumps in residential heating, focusing on their impact on national energy demand, which is a critical factor in achieving full decarbonisation by 2050. Using the End-state Decarbonisation Resource Analysis framework, this study demonstrates that electrification with widespread heat pumps could reduce current residential primary energy demand by over 53%, whereas a hydrogen boiler-dominant pathway could increase demand by 42%. When translated into generation and infrastructure requirements, the hydrogen pathway would demand significantly more resources than the heat pump alternative. Incorporating heat pumps into the electrification strategy would make the delivery of net-zero targets more achievable. Notably, heat pumps could deliver nearly six times higher economic benefits than hydrogen, while requiring only 67% of investment needed for additional generation assets. These findings support prioritising heat pumps over hydrogen boilers in the UK’s national residential decarbonisation strategy.Energie
Mycotoxins: an ongoing challenge to food safety and security
Get PDFThis work was supported by the European Union’s Horizon 2020 research and innovation programme (RISE) through the Marie Skłodowska-Curie grant (Mycobiomics:101008129).PLOS Pathogen
Co-removal of cadmium and F-53B from aqueous solutions using montmorillonite-supported sulfidated nZVI: performance and mechanistic insights
Get PDFThe co-contamination of cadmium (Cd) and per- and polyfluoroalkyl substances (PFASs) in water, particularly from electroplating industries, poses a significant environmental threat. This study presents the first investigation into the simultaneous removal performance and mechanisms of Cd(II) and chlorinated polyfluoroalkyl ether sulfonate (F-53B, a prevalent PFAS alternative) using montmorillonite-supported sulfidated nano-zero-valent iron (MMT/S-nZVI). The composite exhibited high performance, with maximum sorption capacities of 157.5 mg/g for Cd(II) and 22.3 mg/g for F-53B at 25 °C, following pseudo-second-order kinetics. In cocontaminated solutions, MMT/S-nZVI effectively removed simultaneously Cd(II) (50.0 mg/L) and F-53B (1.0 mg/L) under neutral to alkaline conditions, achieving 95.0% Cd(II) and 75.0% F-53B removal at a dosage of 1.0 g/L. A key finding was the asymmetric interaction between contaminants. Cd(II) slightly inhibited F-53B removal, whereas F-53B had a minimal effect on Cd(II) removal. Furthermore, MMT/S-nZVI effectively remediated Cd(II) and a mixture of 11 PFASs at environmentally relevant concentrations (μg/L), although removal was more challenging for short-chain compounds. Mechanistic studies revealed that Cd(II) was removed primarily through electrostatic attraction, ion exchange, and precipitation, while F-53B was adsorbed via electrostatic and hydrophobic interactions. These findings provide key insights into the mechanistic interactions for sorbent development to tackle the critical challenge of heavy metal and PFASs co-contamination in water.This research was supported by grants from the National Natural Science Foundation of China (No. 32061133001), CSCEC Eco-Environmental Engineering Research Center (Soil Remediation Technology and Equipment) (No. CSCEC-PT-009), and Shandong Leading Green Industry Development Corporation (Green Industry and Environmental Safety Innovation and Entrepreneurship Community of Shandong Province) (No. 2023-LSGTT-CX-004).We acknowledge the cooperation between China and the EU through the EiCLaR project (European Union’s Horizon 2020, N°965945).ACS ES&T Wate
Wasim (soil water balance model)
No full textA one-dimensional soil water balance model that partitions daily rainfall into evapotranspiration, surface runoff and drainage. Options allow irrigation to be scheduled according to rules, water table position to be simulated with field under drainage, and soil water salinity to be estimated. The installation package includes a user manual, technical manual and a tutorial with sample data.
[Please note the authors were updated on 01/12/25
Chapter 16: Teaching sustainability: More than just a game
No full textAchieving a sustainable future involves rethinking how we live, work, and do business, and
understanding the steps people and organisations can take to drive these changes. This
involves having a vision of what a just and sustainable future could look like, seeing business
as part of an interconnected system, taking bold decisions and collaborating with others. The
Exploring Sustainable Futures game is a role-playing learning experience that teaches these
skills. Participants experience how the interrelated actions of businesses, government and
citizens shape the future, in the context of four possible scenarios of a sustainable future by
2050. We outline how the design and delivery of the game teaches critical competencies for
sustainability. We offer practical guidance on playing the game with management students
and executive leadership teams. We present emerging evidence on the impact of game play
on participants, and recommend more participatory methods for evaluating learning outcomes