Vicinity Of Pipe Research Articles

Distribution and Deposition of Cylindrical Nanoparticles in a Turbulent Pipe Flow

Distribution and deposition of cylindrical nanoparticles in a turbulent pipe flow are investigated numerically. The equations of turbulent flow including the effect of particles are solved together with the mean equations of the particle number density and the probability density function for particle orientation including the combined effect of Brownian and turbulent diffusion. The results show that the distribution of the particle concentration on the cross-section becomes non-uniform along the flow direction, and the non-uniformity is reduced with the increases of the particle aspect ratio and Reynolds number. More and more particles will align with their major axis near to the flow direction, and this phenomenon becomes more obvious with increasing the particle aspect ratio and with decreasing the Reynolds number. The particles in the near-wall region are aligned with the flow direction obviously, and only a slight preferential orientation is observed in the vicinity of pipe’s center. The penetration efficiency of particle decreases with increasing the particle aspect ratio, Reynolds number and pipe length-to-diameter ratio. Finally, the relationship between the penetration efficiency of particle and related synthetic parameters is established based on the numerical data.

Determination of the resistivity distribution along underground pipes in urban contexts using galvanic and capacitive methods

ABSTRACTRenovation of water and central heating pipelines is a very costly and time‐consuming process; therefore, a way to prioritize the limited resources between different parts of the systems is very important. The risk for corrosion damage can be assessed from the resistivity of the ground, because the processes facilitating the metal oxidation also affect the resistivity. However, galvanic resistivity mapping is time consuming and work‐intensive in paved areas. To determine the resistivity in the vicinity of pipes two different resistivity methods were applied: electrical resistivity tomography using galvanic coupling, and the logistically easier and rapid electrostatic measurements using capacitive coupling. The two methods were tested in a series of experiments undertaken in the province of Scania in southern Sweden with the aim to acquire a better knowledge about the electrical resistivity of the soil surrounding the heating and water distribution pipes, in order to better assess the corrosivity of the environment. From the experiments it is shown that the electrical resistivity tomography and electrostatic methods mostly give comparable results for the shallow investigated depths in focus here, where differences might be caused by different sensitivities and noise characteristics. In the case of both methods, it is shown, with the help of modelling of the different expected ground models including the pipes, that the pipes only influence the data in cases of pipes of very large diameters or those buried at a very shallow depth, even without any protective surface coating. The missing influence of the pipes on the data makes the methods very applicable for knowing the resistivity of the soil surrounding the pipes and thus evaluation of corrosion risk.

Effect of pipe-cooling system on thermal-mechanical behaviour of PC box bridge girders at hydration age

Prestressed concrete (PC) box bridge girders on the pier top is prone to generate thermal cracks due to large inner-outer temperature difference at hydration age. This paper presents an approach for investigating behaviour of PC box bridge girders at early age of curing. First, based on measured data from a typical PC box bridge girder, an inverse analysis method for adiabatic temperature rise function of concrete hydration heat is proposed using genetic algorithm and thermal analysis. Then, a thermo-hydro-mechanical coupling model is established, using the computer program ANSYS incorporating time-dependent wind speed and ambient temperature, to analyse thermal mechanical behaviour of PC box bridge girders considering pipe-cooling system. Subsequently, parametric studies are carried out to evaluate influence of cooling time, cooling water flow rate, cooling water temperature and cooling period on temperature and stress of PC box bridge girders during curing. Results from analysis show that the principal tensile stress generated in the vicinity of pipe increases more rapidly during cooling, while the temperature and principal tensile stress can be significantly reduced when cooling is terminated. Increasing cooling time, cooling water flow rate or decreasing cooling water temperature can reduce the highest temperature. However, unreasonable value of these cooling parameters will cause PC box bridge girders cracking due to excessive principal tensile stress around pipe. Both one-stage and two-stage cooling are effective measures to minimize the adverse effects of hydration heat in PC box bridge girders.

The footprint of the desalination processes on the environment

Processes of desalination of seawater are intended to reduce the deficits in potable water both at present and in the future. Water desalination processes offer various environmental benefits (related to sanitation, water softening, quality of sewage effluents), but the process is also accompanied by adverse environmental effects. These effects can be minimized by the appropriate planning. Most of the effects anticipated would then affect the local environment in the vicinity of the desalination plants. Desalination may have an impact on five domains: the use of the land, the groundwater, the marine environment, noise pollution, and finally the intensified use of energy. The impact on land use is caused by the use of the coastal land for the purpose of building factories, thus converting the coastal area into an industrial zone instead of an area of tourism and recreation. The impact on groundwater mainly occurs if pipelines carrying seawater or brine are laid above an aquifer. It also occurs in the case of feed drilling. In such cases the aquifer may be damaged either by infiltration of saline water or by disturbances of the water table. The impact on the marine environment takes place mainly in the vicinity of the concentrated brine discharge pipe. Even though the concentrated brine contains natural marine ingredients, its high specific weight causes it to sink to the sea floor without prior mixing. In addition, chemicals, which are administered to the water in the pre-treatment stages of the desalination process, may harm the marine life in the vicinity of the pipe's outlet. The actual placement of the discharge pipe may also damage sensitive marine communities. Noise pollution: A desalination plant, which is based on reverse osmosis technology, requires high-pressure pumps, which generate noise. Therefore the plant must be located at a suitable distance from population centers. Technological means may be employed in order to minimize noise intensities. A desalination plant may also affect the environment indirectly, such as via the intensified use of energy by the plant. This increased use of energy results in an increased production of electricity by the respective power station, which in turn results in increased air pollution, pollution by coal dust, thermal pollution, etc. The severity of these effects differs in different areas according to: a) the hydrogeological nature of the marine body (bathymetry, depth, tides, waves, currents); b) the biological sensitivity of the marine habitat; c) the type of desalination plant, its size, the required secondary structures and infrastructure. Environmental awareness and preliminary planning can minimize the adverse effects of the desalination process on the environment.

Diamond exploration in glaciated terrain: a Russian perspective

Glacial and glaciofluvial deposits are widely developed in the Arkhangelsk and Middle Timan areas of the North Russian craton, where numerous kimberlite pipes have been found during the last two decades. These deposits often overlie the pipes and make diamond exploration (particularly mineralogical prospecting) very difficult. They include ground moraine (monolithic till and scaly till facies), end moraines, and glaciofluvial and lake sediments. Kimberlite indicator minerals define haloes of different types in these deposits. Short-distance haloes (1–3 km) form in basal till in the immediate vicinity of pipes, and in glaciofluvial sediments of the alluvial stream facies. They are very small, which makes them difficult to find. Long-distance dispersal trains, extending up to 50–70 km from the sources, are observed in glaciofluvial sediments such as eskers, related to streams overloaded with clastic material. Detached haloes, which have lost their relation to the primary sources, usually are observed in end moraines and modern beach sediments. They reflect the averaged mineralogical composition of all the moraines of the area and thus are useful primarily during reconnaissance exploration. Pyrope and chromite grains in glacial and glaciofluvial sediments show specific surface features reflecting mechanical and chemical alteration during their transport. These features may be used to recognise the mode of transport and possible distance from the primary (kimberlitic) source.