The University of Edinburgh is purchasing a steady flow, high pressure (P < 120 bar) and temperature (T < 1000 K) optically accessible jet and spray research chamber. This chamber is unique within the UK. In addition, the university is also buying a single-cylinder optically accessible research engine. The chamber can be used to study sprays of all kinds; how they develop and react. The engine can be used to study transient fuel sprays as they interact with realistic in-cylinder flows. With this grant, the University of Edinburgh will acquire highly advanced laser diagnostics for multi-parameter measurements in the new chamber and engine, and in other related experimental devices, as a means to leverage the university's substantial equipment investment (£1.4 million) into a UK-wide Small Research Facility (SRF). The measurements to be acquired by this SRF include: a) A femtosecond laser system and ancillary devices (e.g. a second harmonic bandwidth compression system (SHBC), frequency resolved optical gating (FROG) to characterize the pulses etc.). The system will be used for hybrid picosecond/femtosecond rotational CARS (coherent anti-Stokes Raman spectroscopy), for line-image temperature and species (e.g. O2, N2, H2 etc.) in the jet/spray equipment, and ballistic imaging for investigation of primary breakup in highly atomizing sprays. b) High-speed (HS) 2-pulse, 532 nm wavelength laser and HS imaging systems for HS stereoscopic PIV, SLIPI imaging, and LII for particulate. A HS 1-pulse, 355/266 nm wavelength laser and HS intensifier system for HS PLIF, phosphors, and LITA. c) A phase Doppler instrument for droplet/particle size distribution and velocity in reactive jets and sprays The combined equipment and diagnostics will enable new studies on: a) Fuel sprays (including alternative fuels), and b) Supercritical materials synthesis (biofuels, pharmaceuticals, nano-catalysts, polymers etc.). Our research goals are multi-faceted. The research will enable more efficient combustion engines, reducing their impact on the climate. It will also make it possible to understand and then improve supercritical processing for materials synthesis, helping bring such products to market more effectively. In so doing we will address critical needs for both established industries and for key emerging industries across the UK.

Energy demand will be up by more than a quarter by 2040 [International Energy Agency data]. Given the dominance of combustion in meeting this demand, it is imperative to develop low-carbon, efficient gas turbine (GT) engines to reduce emissions impact and tackle the global warming as set by the Paris Agreement. In recent years lean premixed technology has attracted interest due to its potential of reduced emissions and high efficiency. However, lean combustion is prone to instabilities that may lead to unwanted oscillations, flame extinctions and flashbacks. Use of low or zero-carbon fuels like hydrogen is also limited because the high speeds needed to prevent flashbacks due the high low-heating values (LHV) can destabilise the vortex dynamics. Further development is thus required to achieve better efficiency and lower emissions, and effective flame holding techniques are crucial for this development. In ultra-compact combustor design, trapped vortex (TV) systems are implemented either in the primary zone or in the inter-turbine region to increase the resident time of combusting gases, resulting in better mixing, thus higher efficiency and lower emissions. Higher resident times also imply a shorter combustor, thus a lighter engine and less fuel consumption, also helping the process of hybridisation in multi-cycle devices. TV are locked stably within a cavity and thus are less sensitive to external disturbances even at high speeds, allowing use of low or zero-carbon fuels with high LHV like hydrogen. However, the process of flame stabilisation is rather complex because of the shear and boundary layer (BL) vortex dynamics, the strong heat transfer to the wall and the simultaneous occurrence of flame propagation and auto-ignition processes. The effective control of the flame dynamics requires a deep understanding of these processes. This project aims to develop improved understanding of the fundamental processes governing flame stabilisation in TV systems for ultra-compact combustion design, and their potential to deliver improved flame stability and low emissions at high speed (subsonic) conditions in the context of lean premixed technology. In particular, the TV physics will be studied i) in presence of a radially accelerating flow representing the swirled flow dynamics at the entrance of the combustion chamber; and ii) in presence of an axially accelerating flow when the cavity is located within the converging duct near the combustor exit. Both swirled and axial acceleration can destabilise the vortex dynamics, so this dynamics has to be understood before TV systems can be effectively employed. The analyses will be conducted through high-fidelity large eddy simulations (LES), which represents a cost-effective tool as compared to expensive experimental investigations. In this way the effect of turbulence, equivalence ratio and cavity geometry can be explored in details via parametric study. Moreover, the performance of different alternative fuels and their implication in terms of flame holding and model performance can be evaluated for different TV designs. An improved model involving presumed PDF approaches based on mixed flamelets/perfectly stirred reactor will be developed to account for the aforementioned physics. The fundamental understanding for this development will be extracted from unprecedented detailed direct numerical simulation (DNS) and by using validation data from experiments provided by the project partners. The outcomes of this project will significantly help the development of modern, low-carbon engines, and improve the understanding of the fundamental physics within these devices. Moreover, the project will lead to the development of CFD codes and models that can be used in industrial design cycles. Thus, this project is timely and strongly relevant for leading UK industries such as Rolls-Royce and other emerging industry, and will help them to maintain their leading role in the power-generation sector.

Quantum information science promises to fundamentally change the way we do things, not unlike how classical information science continues to change every aspect of our daily lives. Classical information science teaches us how difficult it is to break a cipher, or how long it will take a computer to do a calculation; quantum information science predicts fundamentally secure cryptography, and computers that solve certain problems faster than any conceivable classical machine. At first glance, it is surprising to think that randomness can actually help perform information processing tasks, and yet it can: for example, a random cryptographic key is known to be the best way to hide messages; more surprisingly, there exist problems where, rather than execute a deterministic algorithm as classical computers normally do, it is better to guess -- that is, invoke randomness -- while computing a solution. Thus we say that randomness is a resource in classical information theory; having a coin at hand that one can flip is a tangible asset. This is especially true when one wants to test a complex device or process: send it random inputs, and investigate how the outputs behave. We can also purposely introduce randomness into quantum information protocols and ask if this can make certain tasks easier. It turns out the answer is also yes, giving rise to the study, for example, of random quantum circuits, or random quantum error correcting codes. In the formalism of quantum mechanics these are expressed as random operators, rather than simple random numbers, but they can be thought of as resources for quantum information science in much the same way as in the classical case. However, both classically and quantumly, generating truly random resources is very difficult; one can imagine trying to encrypt terabytes of information by flipping a coin billions of times. In practice we rely on so-called pseudorandom resources that, given a finite amount of time or computing power, can never be distinguished from truly random. If we think of increasingly complex tests one might do to check for randomness, a pseudorandom resource will pass these tests up to a certain level of complexity (and fail beyond that). Such resources are much easier to create than truly random ones, and pseudorandom number generators are a cornerstone of today's information technologies. This research project aims to make pseudorandom resources available to quantum information technologies. In the quantum realm, the notion of pseudorandomness is captured by what are called quantum 't-designs'. These are resources -- ensembles of quantum operators -- that pass randomness tests up to some level of complexity (more precisely, t corresponds to the degree of a statistical moment). The project has two main components; the first will be a systematic study of the mathematical structure of t-designs, finding new ones along the way, and then optimising these resources for specific quantum technologies; at the University of Bristol a technology we focus on is integrated quantum photonics, and so the second part of this project will be to use our theoretical work to propose and perform quantum photonic experiments that demonstrate quantum pseudorandomness. Quantum technology is in its infancy, and this research will be an important early step in understanding and solving the problem of efficiently producing the randomness that is crucial to information science. In the short term, the results will be used to tackle challenging problems such as finding the best way to characterise increasingly complex quantum devices, like the ones being developed by hundreds of partners in the UK Quantum Technology Network. In the longer term, it will enable customised, plug-in pseudorandom resources for any quantum platform, which will be used in a multitude of future quantum information applications.

In recent times, immense efforts have been made in engine research to develop new concepts, from common-rail Diesel and GDI to HCCI (now primarily seen as an operating mode of the aforementioned), in order to meet increasingly-stringent demands for fuel consumption and emissions reductions. There is an urgent need for accurate simulation tools, ideally applicable to all engine types and operating modes, to assist engine designers to meet these targets. The modelling of turbulent reactive flows has always been a trade-off between capturing the complexity of the flow and the complexity of the chemical kinetics (with due regard for turbulent-chemistry interactions), due to the limitations in computer resources. The former is particularly demanding in ICE modelling and has tended in the past to receive most of the attention, but over the past decade increasing effort has gone into the combustion modelling, due to the availability of high-power and low-cost computers. IC engine development leads towards novel diesel combustion concepts that break the traditional NOx vs. PM trade-off of classic diffusion controlled combustion require. Pollutant formation in Diesel engines is mainly mixing controlled and a better understanding of the complex turbulence-chemistry interactions that strongly influence the formation and destruction of pollutants is required. The proposed research will extend the existing CFD methodology for engine simulation to accurately account for (i) mixing of fuel and oxidizer, especially due to large-scale motion, (ii) turbulence-chemistry interactions and (iii) cycle-to-cycle variations that cannot be predicted by current state-of-the-art three-dimensional Reynolds-averaged simulations (RAS). It is widely accepted that large-eddy simulation (LES) holds the largest potential of all present fluid dynamics models to accurately capture large-scale mixing and cyclic effects of in-cylinder motion, however, LES needs be combined with advanced combustion models for the correct treatment of the turbulence-chemistry interactions. Very recent studies have established the potential of the conditional moment closure (CMC) approach as a suitable combustion model for IC engines and as a suitable combustion sub-model in the LES context. This potential will now be exploited and the integration of CMC into LES for engine computations is at the core of this project. The research will primarily focus on the closure of the turbulent reaction rate term, associated turbulence-chemistry interactions and improvements to pollutant predictions. The effects of LES modelling on droplet motion, large-scale fuel-oxidizer mixing and the predictability of cyclic variations will be assessed. The LES-CMC approach will be validated by comparison with measurements from engine-like experiments of increasing complexity and trends for the dependence of NOx and soot emissions on engine operating conditions will be investigated.