An analysis of incoming wind pulsation on the wind erosion processes on a hill

The present analysis undertakes the problem of surface wind over topography. The main focus is placed upon the effect of oncoming wind oscillations on the velocity field structure around a single sinusoidal shaped 2D hill. Additional effort has been undertaken to recognize the inflow gust influence on the surface shear stress related to the mechanism of wind induced erosion. Numerical simulations have been performed through the use of the phase-averaged form of RNG version of k-ɛ turbulence model. Experimental verification of numerical data has been done in wind tunnels equipped with devices generating unsteady wind boundary layers. The main findings of the simulations reveal: a strong dependence between the characteristics of inflow periodicity and the structure of vortices of the separation region; the mean position of the reattachment point; the phase averaged velocity field; skin friction variability downstream from the hill. The results have significant implications for the prediction of sand transport in unsteady winds

Dobór kryteriów oceny komfortu wiatrowego pieszych

Wind comfort in an built-up areas may be affected by a wide range of parameters, including wind speed, air temperature, relative humidity, solar radiation, air quality, human activity, age, etc. In practice, the assessment of the pedestrian comfort is carried out on the basis of the indexes defined to a considerably smaller number of parameters. Generally it is a criterion of wind velocity with the probability of exceeding the assumed discomfort threshold. This article discusses issues of spatial planning built-up areas including wind comfort criteria. The article pointed out the role of criteria adopted in estimation of discomfort areas. An important role is played here the value of the amplitude of the gust factor g. The attention was also drawn to the strong time variability of discomfort zones especially in areas close to buildings.Komfort wiatrowy pieszych zależy od wielu czynników: prędkości wiatru, temperatury i wilgotności względnej powietrza, stopnia nasłonecznienia, jakości powietrza, aktywności pieszych, wieku i innych. W praktyce ocenę komfortu pieszych przeprowadza się w oparciu o współczynniki zdefiniowane na znacznie mniejszej liczbie parametrów. Najczęściej jest to kryterium prędkości wiatru wraz ze stopniem prawdopodobieństwa przekroczenia założonej granicy dyskomfortu. W niniejszym artykule omówiono zagadnienia planowania przestrzennego obszarów zabudowanych z uwzględnieniem kryteriów komfortu wiatrowego. W artykule wskazano na rolę kryteriów jakie przyjmuje się przy oszacowaniu obszarów dyskomfortu. Istotną rolę odgrywa tutaj wartość współczynnika amplitudy podmuchu g. Zwrócono również uwagę na silną zmienność stref dyskomfortu w czasie zwłaszcza w obszarach bliskich obiektów

Modeling of Thermal Cycle CI Engine with Multi-Stage Fuel Injection

This work presents a complete thermal cycle modeling of a four-stroke diesel engine with a three-dimensional simulation program CFD - AVL Fire. The object of the simulation was the S320 Andoria engine. The purpose of the study was to determine the effect of fuel dose distribution on selected parameters of the combustion process. As a result of the modeling, time spatial pressure distributions, rate of pressure increase, heat release rate and NO and soot emission were obtained for 3 injection strategies: no division, one pilot dose and one main dose and two pilot doses and one main dose. It has been found that the use of pilot doses on the one hand reduces engine hardness and lowers NO emissions and on the other hand, increases soot emissions

Use of Hydrothermal Carbonization and Cold Atmospheric Plasma for Surface Modification of Brewer’s Spent Grain and Activated Carbon

This paper presents results that show the effect of hydrothermal carbonization and subsequent cold plasma jet treatment with helium and argon on the structure and sorption properties of a material—spent brewery grain. Treatment of activated carbon, with a cold atmospheric plasma jet, was used comparatively. The effect of activation on the pore structure of the materials was carried out by the volumetric method at low pressure (N2, 77 K). The specific surface area as well as the total pore volume, average pore size, and pore size distribution were determined using different theoretical models. A high improvement in the sorption capacity parameter was obtained for hydrochars after cold atmospheric plasma jet treatment with an increase of 7.5 times (using He) and 11.6 times (using Ar) compared with hydrochars before cold atmospheric plasma jet treatment. The increase in specific surface area was five-fold (He) and fifteen-fold (Ar). For activated carbon, such a large change was not obtained after plasma activation. Regardless of the gas used, the increase in structural parameter values was 1.1–1.3

Numerical analysis of oscillating flow around a cylinder

This paper presents the numerical model of the measuring stand - the wind tunnel, in which there is fixed a cylinder with a turbulent inlet oscillating stream. The aim of this work is the juxtaposition and comparison of characteristic values concerning the oscillating turbulent flow around the cylinder, obtained from the experiment conducted in the wind tunnel at the Institute of Thermal Machinery with the data obtained as a result of numerical modelling of unsteady phenomena. The model discussed in this paper was created using a commercial program ANSYS FLUENT that is used for mathematical modelling of flow and heat transfer processes. The expected outcome of this study is possibility of the numerical modelling of the stand concerning the analogous unsteady flows without significant investment of time. Comparison of longitudinal and transverse velocity profiles in aerodynamic wake and the pressure coefficient distributions on the cylinder surface show similarities between experimental and numerical studies

THE URBAN PLANNING IN ACCORDANCE WITH SUSTAINABLE DEVELOPMENT USING MODELING METHODS

The paper presents the concept of urban planning in accordance with sustainable development using modeling methods (experimental and numerical). The integrated approach to urban planning in this case means used interdisciplinary knowledge derived from: eco-construction, energy supply systems, but also the development of wind climate in cities and settlements (i.e., environmental aerodynamics). The subject of this study is a tandem arrangement of two rectangular blocks, which is characterized by the appearance of down-wash effect. The geometry was chosen based on the literature, which shows the case analyzed here, as a common architectural error that leads to extremely adverse effects of wind

THE URBAN PLANNING IN ACCORDANCE WITH SUSTAINABLE DEVELOPMENT USING MODELING METHODS

The paper presents the concept of urban planning in accordance with sustainable development using modeling methods (experimental and numerical). The integrated approach to urban planning in this case means used interdisciplinary knowledge derived from: eco-construction, energy supply systems, but also the development of wind climate in cities and settlements (i.e., environmental aerodynamics). The subject of this study is a tandem arrangement of two rectangular blocks, which is characterized by the appearance of down-wash effect. The geometry was chosen based on the literature, which shows the case analyzed here, as a common architectural error that leads to extremely adverse effects of wind

Selection of criteria in pedestrian wind comfort assessment

Wind comfort in an built-up areas may be affected by a wide range of parameters, including wind speed, air temperature, relative humidity, solar radiation, air quality, human activity, age, etc. In practice, the assessment of the pedestrian comfort is carried out on the basis of the indexes defined to a considerably smaller number of parameters. Generally it is a criterion of wind velocity with the probability of exceeding the assumed discomfort threshold. This article discusses issues of spatial planning built-up areas including wind comfort criteria. The article pointed out the role of criteria adopted in estimation of discomfort areas. An important role is played here the value of the amplitude of the gust factor g. The attention was also drawn to the strong time variability of discomfort zones especially in areas close to buildings

The role of inflow boundary layer thickness for numerical modelling of flow around bluff bodies of built-up areas

The paper presents the numerical results obtained with the use of the ANSYS FLUENT commercial code for analysing the flow structure around a two rectangles in line surface-mounted bluff bodies immersed in a boundary layer. The simulation of a configuration with a flow around objects has been done using both the steady and unsteady approaches. Effects of the inflow boundary layer thickness on the flow field, wall-shear stress and the grid resolution accuracy in predicting periodic vortex shedding from two tandem arrangement bodies are examined. It has been observed that the periodic vortex shedding is considerably reduced with an increase in the δ/H parameter

The Place of Photovoltaics in Poland’s Energy Mix

The energy strategy and environmental policy in the European Union are climate neutrality, low-carbon gas emissions, and an environmentally friendly economy by fighting global warming and increasing energy production from renewable sources (RES). These sources, which are characterized by high investment costs, require the use of appropriate support mechanisms introduced with suitable regulations. The article presents the current state and perspectives of using renewable energy sources in Poland, especially photovoltaic systems (PV). The specific features of Polish photovoltaics and the economic analysis of investment in a photovoltaic farm with a capacity of 1 MW are presented according to a new act on renewable energy sources. This publication shows the importance of government support that is adequate for the green energy producers