Digital manufacturing is aligned well with the UK Industrial Strategy to become a more innovative-based economy and to support for commercialisation. Additive manufacturing (AM) - an upcoming and disruptive digital technology - is tractable for a wide range of applications ranging from biomedical to aerospace industrial sectors. With the technological benefits of manufacturing flexibility, consecutively adding material layer-by-layer enables sophisticated and complex parts to be additively manufactured with minimal waste, created timely and cost effectively. However, investment in basic scientific understanding of the AM process plays a major role in the successful adoption of the metallic AM in aerospace and biomedical applications. This will help the UK develop technical-level skills and trained people to progressing technologies from laboratory to commercial success. The project, therefore, fits the need of this priority area. The work concerns about the simulation of solid-liquid-vapour transition and relevant thermal fluid mechanics at the AM technological applications. The aim is to use computational modelling to design AM alloys and improve the AM processing through the optimisation of chemical constituents and process conditions, which will be backed up with through-process testings. Non-equilibrium databases for thermo-physical properties will be obtained for establishing processing-structure-property-performance relationship using theory, experiments and computation under the framework of integrated computational materials science. A science-based AM design rule is derived to maximise the use of raw materials with zero-waste and recyclable fashion, and to ensure the integrity of additive manufactured components for repair technology in aerospace usages. It is also anticipated that the effective use of AM technology in aerospace sector especially for repair and manufacturing purposes will lead to disruptive innovation in other innovative technologies such as medical applications.

The contrail climate impact of future low-CO2 aircraft will be assessed, incorporating rigorous analysis of turbulence/microphysics interactions into climate-optimised aircraft design. Aircraft contrails and contrail cirrus may account for more than half of the climate forcing from aircraft operations to date. Radically different airframe and propulsion concepts have been developed as a means to reduce CO2 emission, but the impact of these developments on contrail formation has not been part of the design process. Contrail formation in the aircraft wake is affected by the wing planform and the type and positioning of the propulsors, but established contrail formation models have been developed only with reference to conventional tube-wing aircraft architectures. This limits their applicability - alternative aircraft technologies affect the distribution of ice particles that form, requiring re-evaluation of the climate forcing that results from choosing different technology pathways. Building on the project team's expertise in modelling complex interactions of mixing, microphysics and atmospheric processes, methods will be developed to assess how different aircraft and propulsion architecture choices affect the climate impact of future aircraft. Climate-optimised development of advanced aircraft concepts will be demonstrated. Effects of advanced aircraft architectures on contrail development will be studied computationally and incorporated into a new contrail simulation approach that accounts for detailed contrail microphysics in high-throughput design calculations. Methods for assessing the climate forcing due to alternative technologies and operating strategies will be incorporated into freely available software that takes account of the detailed development of contrail cirrus. Through participation of forward-looking airframe and propulsion system manufacturers, this project will directly inform the path we take to minimise the overall climate impact of future aviation.

The context of the work: Theme 1.2 - "Better understanding the formation of nitrogen oxides emissions from aircraft and their climate impact" and "increasing understanding over the future net nitrogen oxides effect, and whether it is likely that this will switch from warming to cooling". Radiative forcing of climate is the concept by which effects are quantified. Prior research has shown that aviation 'net NOX' radiative forcing (RF) may switch from positive to negative, in the future. Aviation NOx emissions cause complex changes in atmospheric composition, resulting in positive (from short-term ozone) and negative (from reduced background methane, stratospheric water vapour, background ozone and nitrate aerosol) stratospheric-temperature adjusted radiative forcings (SARF). Positive and negative forcings are interpreted, to a first order, as warming and cooling, respectively. However, the temperature responses may not be linearly additive , and may be spatially and hemispherically variable, such that a global mean net NOx SARF may be an inadequate indicator of mitigation responses. A recent assessment of the climate impact of aircraft NOx presented a 'Net NOx response' from many model experiments. To estimate the effective radiative forcing (ERF) - an improved measure of the RF concept - only one model estimate of the 'efficacy' of aircraft-induced ozone and methane perturbations was available, making this last adjustment in the assessment significant but highly uncertain. Efficacy of aircraft NOx forcings are the focus of this novel work. The challenge that this project addresses: to estimate the global pattern of temperature response and improve the poorly-characterised ERF:RF ratio resulting from aviation NOx emissions for present and future scenarios of aviation and background emissions. The aims are as follows:To perform improved research so that aircraft engine manufacturers can make better informed decisions on the requirement or otherwise, for improved combustor design for reduced NOx emissions. To characterise the net NOx response of aviation and improve the quantification of the ERF effect To determine the global and hemispheric temperature responses of the ERFs induced by aviation scenarios. The objectives are as follows: To perform new model calculations of aviation NOx effects on atmospheric composition and calculate ERF with two state-of-the-art Earth System Models (UKESM, WACCM/CESM2) for current and future scenarios. Chemistry simulations will be performed with realistic emissions fields, so as not to encounter non-linearity problems. The resultant composition fields will be used, amplified to overcome signal-to-noise problems, to force a climate model to determine changes in global mean surface temperature response. Using a coupled ocean-climate model, the full climate response and its time evolution will be calculated. The potential applications and benefits are: The project will benefit industry, policy makers and regulators in making better informed decisions as to whether future NOx regulation for climate through ICAO is likely to be required or not. The basic principles of ERF and temperature response will be elucidated (TRL1) and produce a Technology Concept (TR2) of how engine manufacturers might consider the necessity of NOx reduction in future combustor design. The scientific advances will benefit the research community in better characterising the ERF and temperature responses of small perturbations to the climate system, and methodologies over attribution of sectoral responses to emissions.

With the need for the development of novel hydrogen-compatible combustion devices, physical understanding of the flame behaviour and the identification of thermoacoustic instabilities at relevant combustor operating conditions for hydrogen-air swirl flames will help speed up the development of hydrogen combustors, in line with the UK government's net-zero vision. The proposed research will offer potential benefits to industry and contribute to the progress of science in the areas of fluid dynamics, turbulence and net-zero combustion. These include (i) An advanced Direct Numerical Simulation (DNS) database for hydrogen-air premixed swirl flames under representative combustor operating conditions. (ii) A comprehensive understanding and a detailed analysis of the behaviour of the Precessing Vortex Core (PVC) under non-reacting and reacting flow conditions. (iii) Identification of the combustor operating conditions for which hydrodynamic/thermoacoustic instabilities exist. (iv) An in-depth analysis on extinction strain rates and heat release rate for lean hydrogen premixed flames. The outcomes of this project will offer knowledge on the flame stability limits and will contribute to the development of hydrogen based power generation and propulsion devices (e.g. gas turbines used for power generation and aircraft engines).

The design of complex couplings and connections against failure is a key topic for the optimisation of key aeroengine components, which represents a vital challenge for the sustained competitiveness of the British aeroengine industry. The difficulties associated with gaining access to the intimate contacting regions of such components provides an opportunity for computational modelling and predictive techniques. This project will bring about a quantum leap in the application of modelling techniques to the design of engineering contact connections through the consolidation of a number of different techniques. The key techniques that will be incorporated in the tool to be developed are: (i) finite element based modelling of material removal due to fretting wear action, (ii) asymptotic solutions for characterising the multiaxial stress states for cracking prediction at sharp contact edges and steep contact stress gradients, (iii) the use of multiaxial representative testing techniques for obtaining cycle-dependent frictional contact data(iv) a combined wear-fatigue prediction technique to provide a fretting fatigue damage parameter that captures the effects of slip amplitude.The tool will be applied to realistic three-dimensional aeroengine demonstrator components and validated against existing test data from previous EPSRC-funded work.