The liquid lithium loop included as part of the EuroFusion IFMIF-DONES facility presents a unique fire risk via the possibility of lithium leaks. While the least reactive of the alkali metals lithium can react violently with oxygen, nitrogen, CO2 and water. This risk doesn’t fit with any typical fire testing apparatus, and so to investigate the potential for fires arising from a leak, and the potential of mitigation measures new apparatus was needed to be designed. This paper documents the design of a new piece of apparatus, consisting of 2 chambers (for preparing and then exposing the lithium to reactants) and a contenting device for melting the lithium. Some initial testing of the apparatus was undertaken and its performance evaluated, with weaknesses identified and a route forward for future studies decided.

Understanding the formation and behaviour of sprays and aerosols generated by vehicles traveling on wet surfaces is crucial due to their impact on vehicle soiling, visibility, and autonomous driving. These sprays and aerosols can reduce visibility for other drivers, contribute to traffic accidents, and reduce the operational capabilities of sensors for driving assistance systems and future autonomous vehicles. Despite the critical importance of understanding the physical properties of these sprays and aerosols for the testing and validation of sensors used in environmental perception and recognition, field data on this subject remains limited. The formation and behaviour of these sprays and aerosols are complex. A fraction of the trailing droplets and ligaments originates directly from the tyres, while the remainder is generated upon the impact of the particles ejected from the tyres with the vehicle's wheel houses and other surfaces, resulting in either coalescence or further disintegration. Aerodynamic forces also significantly influence the formation of these sprays and aerosols. Although experimental studies have investigated the droplet field around rotary atomisers, there is little published information on the droplet size distribution and number density of the spays around wet tyres under real-like conditions. This work aimed to characterise the sprays and aerosols produced by commercial tyres rotating on wet surfaces. Measurements of droplet size distribution, number density, and contrast degradation were conducted under controlled conditions using optical methods and a test rig. The rig allowed for testing with variations in water depth, rotational velocity, and tyre tread pattern, with measurements taken at various distances from the tyre surface. The results indicate that the mean droplet size (arithmetic) correlates with the tyre's rotational speed but is only weakly influenced by water depth or tyre tread pattern. In contrast, the number density is significantly affected by all of these factors, while contrast degradation is influenced, though weakly, by the tested variables.

This research investigated visibility degradation caused by vehicle-generated water sprayon wet surfaces, using experimental tests, simulations, and data analysis to examine spraydynamics and their effects on camera and sensor performance.Dynamic tests faced challenges with automated contrast analysis due to insufficientresolution, lack of camera calibration, and poor lighting. Targets were too small inimages, and low contrast, even without spray, prevented reliable detection. Similar issuesaffected static tests, although higher light levels enabled more consistent results. Highbeamheadlights worsened contrast degradation by illuminating spray particles. Thesefindings emphasized the importance of proper calibration, resolution, and lighting foraccurate data collection.Outdoor tests on AstaZero test tracks showed that water depth and vehicle speedsignificantly influence spray and visibility. Deeper water (e.g., 9–10 mm) caused greatercontrast degradation than shallower water (e.g., 4–5 mm), while higher speeds amplifiedspray effects, particularly in shallow water. Variations in light conditions affected theresults, with clearer patterns emerging under stable lighting.Tyre rig tests provided detailed measurements of aerosol and water spray properties, suchas droplet size, density, and distribution. Smaller droplets (mode below 50 μm) formednear the tyre surface, while larger droplets developed downstream due to coalescence andaerodynamic forces. Higher tyre speeds and more water increased spray density andcontrast degradation. In deeper water, contrast degradation was more uniform, withnarrower ranges between maximum and minimum values.Simulations revealed key mechanisms of spray generation and propagation. Water filmdepths as low as 100 μm produced spray through capillary adhesion, with dropletsinteracting with vehicle components and airflow. Larger droplets returned to the groundquickly, while smaller droplets remained suspended, affecting visibility. Data collectedunder naturalistic conditions validated these findings and provided insights into realworldvisibility challenges.This research highlights the critical role of water depth, vehicle speed, and spraydynamics in visibility degradation. It underscores the need for improved measuringmethods, lighting, and testing protocols to enhance automated analysis and sensorperformance, especially for autonomous vehicle systems in adverse weather conditions.

Sprays produced by injecting water into quiescent air by three different types of nozzles were characterised by optical methods. The droplet velocities and droplet size distributions were assessed by the use of high speed shadowgraphs.

Scheimpflug lidar is a compact alternative to traditional lidar setups. With Scheimpflug lidar it is possible to make continuous range-resolved measurements. In this study we investigate the feasibility of a Scheimpflug lidar instrument for remote sensing in pool flames, which are characterized by strong particle scattering, large temperature gradients, and substantial fluctuations in particle distribution due to turbulence. An extinction coefficient can be extracted using the information about the transmitted laser power and the spatial extent of the flame. The transmitted laser power is manifested by the intensity of the ‘echo’ from a hard-target termination of the beam located behind the flame, while the information of the spatial extent of the flame along the laser beam is provided by the range-resolved scattering signal. Measurements were performed in heptane and diesel flames, respectively. © 2023 The Author(s). 

Under certain conditions dust explosions occur in the alimentary industry. Following ATEX and other guidelines have not eliminated accidents. Therefore, more knowledge is needed. The current work delivers experimental results describing phase transitions and decomposition of dusts. Dusts from wheat flour, chili powder, corn starch, milk powder, cocoa powder, and by-product of grain are investigated. The temperature of pyrolisation has been identified using TGA to be in the range [250°C, 600°C] in air and [300°C, 450°C] in nitrogen. It was found that the compositions of the pyrolysis gases depend on temperature. Carbon monoxide, carbon dioxide, methane, and hydrogen were the main contributors to the pyrolysis gases. The distributions are described with a polynomial or Gaussian fit. The current paper proposes coefficients for Gaussian polynomials expressing the concentration for the four primary pyrolysis gases. 

The ignition of natural fuels by sparks from strikes between metals and hard rock is far from understood and the ignition potential of sparks from rock strikes during heavy machinery operations is disputed in the scientific literature. This study utilises a spectrally resolved technique to study the temperature evolution of metal sparks from rock strikes. The study shows that initial temperature after collision can easily reach 1500 °C and this temperature can increase additionally by several hundred degrees as rapid oxidation processes are initiated, often leading to further disintegration of the fragment. The average temperature of fragments from such collisions is here measured to 1400 – 2000 °C and the combination of temperature, size and exothermic processes makes them viable for forest litter igniting. However, ignition on forest lands is always an unlikely, although possible outcome of heavy machinery operations and should be considered in risk assessment of the activity.

Soot particle size, particle concentration and volume fraction were measured by laser based methods in optically dense, highly turbulent combusting diesel sprays under engine-like conditions. Experiments were done in the Chalmers High Pressure, High Temperature spray rig under isobaric conditions and combusting commercial diesel fuel. Laser Induced Incandescence (LII), Elastic Scattering and Light Extinction were combined quasi-simultaneously to quantify particle characteristics spatially resolved in the middle plane of a combusting spray at two instants after the start of combustion. The influence that fuel injection pressure, gas temperature and gas pressure exert on particle size, particle concentration and volume fraction were studied. Probability density functions of particle size and two-dimensional images of particle diameter, particle concentration and volume fraction concerning instantaneous single-shot cases and average measurements are presented. High injection pressure led to a reduction in the mean particle size, total number of particles and total amount of soot compared to a low injection pressure. Higher gas pressure resulted in larger amount of soot and larger soot particle size, with higher gas temperature having similar effects. 

Heavy vehicles rolling on wet roads produce splash and spray clouds. These aerosols reduce the visibility of other drivers, contribute to a small, but quantifiable proportion of road traffic accidents and affect the operational capabilities of autonomous vehicles travelling near them. Even though knowing the physical properties of these aerosols is essential for testing and validating sensors for environment perception and recognition of autonomous vehicles, there is little information about them. In this work the physical characteristics of spray clouds produced by heavy vehicles rolling on wet asphalt were measured by optical methods. Time resolved droplet size, mass concentration, number density, light extinction and contrast attenuation parallel and perpendicular to the travelling direction of the vehicle were measured. Vehicle velocity, vehicle configuration and water depth were varied during the tests. Results show that the average droplet diameter ranges between 100 and 400 μm with maximum diameters of almost 4 mm. Mass concentration gamuts between 0,2 and 0,7 kg/m3 with peaks surpassing 1 kg/m3 while number density spans between 20 and 40 cm−3 and occasionally exceeds 100 cm−3. Light extinction can reach levels as high as 0,2 m−1 and contrast, evaluated from images, can reach values under 0,1.