Tomasz Seredyn, Adam Dziubiński and Piotr Jaśkowski
The article describes a computational study, using CFD models, of droplet spray dispersal in the wake of a ‘Turbo Kruk’ airplane up to 500 m downstream. The CFD Reynolds-averaged Navier-Stokes (RANS) models use a Lagrangian (droplet phase) and Eulerian (fluid phase) procedure to predict the droplet trajectories trough the turbulent aircraft wake. The methods described in the work have the potential to improve current models for aerial spraying and will help in the development of new spraying procedures. In this study, the CFD models are used to describe the phenomenon of sprays released from atomizers mounted on the plane. A parametric study of the aircraft model examines the effects of crosswind on the aircraft’s vortex structures and the resulting droplet trajectories. The study shows, that such influence is underestimated in the current models. A comparison of the present results to AGDISP predictions is provided.
Adam Hofman, Jarosław Sowiński and Marek Dziubiński
The change in water quality in small water systems is strongly affected by sediment particles. Their transport, deposition and re-suspension due to variability in water demand has a significant impact on the change in water quality. Two significant mechanism of deposit transport and deposition i.e. turbophoresis and turbulent diffusion have been described in the literature. The paper presents the mechanisms of turbophoresis and turbulent diffusion. These phenomena have an impact on the quality of water in small water systems. The aim of the study is to propose procedures of identifying areas of mechanism of particle movement and their accumulation in small water system networks. Simulation of the flow of small water-pipe network at Niewiesz was used for the study. That water pipeline is situated in the central Poland. Many rural areas in Poland have a similar architecture. Modeling of movement of contaminant in close wall areas in pipelines is presented. The article presents the discussion concerning the areas where the mechanisms of turbophoresis and turbulent diffusion occur in the transport of solid particles in water supply systems. The relations between deposition and transporting of particles in turbulent flows depend on a number of parameters, including: particle size, localization of particles in the pipe (at given time), as well as the turbulence of flow. These parameters change depending on the water demand. The type of these changes depends on pipe diameters, material from which the pipes and the fittings are made, water demand and initial quality of water.
Dorota Brzezińska, Marek Dziubiński and Adam S. Markowski
Despite the fact that LPG (Liquefied Petroleum Gas) is used in a large number of cars, tests have not yet been carried out to ascertain how hazardous can be the release of LPG from the car when parked in enclosed garages. The problem applies to both public and industrial parking areas, especially in Poland, where more than 10% cars are fueled by LPG. The paper describes full scale experiments, which demonstrate conditions that may occur in a garage in the event of accidental LPG release from the car installation. Over the course of the tests, a series of six LPG spillage tests were performed to study emission time and flammable cloud formation depending on the accidental gap diameter. Additionally, to enable the visual observation of the gas dispersion and influence of the ventilation system the experiment was conducted using well visible CO2 gas cloud, produced from dry ice. The experiments have shown that without ventilation LPG can accumulate on the floor of the enclosed garage for a long time, which generates a high explosive hazard. However, good ventilation (especially jet fan systems) can quickly remove hazardous flammable LPG clouds. Moreover, very important for effective LPG detection is the location of detectors closer to the floor than is currently recommended - at a height of 30 cm.