Filtry
wszystkich: 94
wybranych: 79
Wyniki wyszukiwania dla: TURBULENCJA
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Flow Analysis of a Kaplan Turbine
PublikacjaThis monograph is a guide to a method of experimental and numerical flow investigations for Kaplan - type turbines. The numerical calculations were compared with the test results of the model Kaplan turbine. The tests were carried out on the model test rig in the Gdańsk University of Technology. The turbine has been thoroughly experimentally investigated, resulting in the identification of optimum setting combination of the stator...
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Comparative Analysis of Numerical and Experimental Studies of the Airflow Around the Sample of Urban Development
PublikacjaIn this paper, on the background of a short overview of the recent advances in the field of Environmental Wind Engineering (EWE), a comparison of wind tunnel experiment and numerical simulation for some cases of airflow around an urban layout have been reported. The purpose of the study is quantitative and qualitative comparison of measurements in the wind tunnel as well as numerical simulation using Ansys Fluent software. The...
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Flow of liquid in flat gaps of the satellite motor working mechanism
PublikacjaThe article describes the methodology and results of investigations of the flow of oil and HFA-E emulsion in flat gaps of the working mechanism of a satellite motor. The flow of liquid in those gaps is turbulent and not fully developed. The article presents two methods of modelling this flow. Method I makes use of the Darcy-Weisbach formula, while Method II bases on the assumption that in the variable-length gaps the flow is turbulent...
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A conceptual design and numerical analysis of the mixerless urea-SCR system
PublikacjaIn the present study, an innovative design of the urea-selective catalytic reduction (SCR) system without conventional mixing elements was developed. The aim was to obtain a high degree of urea decomposition, and uniform ammonia distribution at the inlet to the catalyst, while minimising the liquid film deposition and keeping the compact design. The concept of the design was based on creating high turbulences and elongating...
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A numerical and experimental analysis of multi-hole orifice in turbulent flow
PublikacjaIn this research study, the comprehensive metrological analysis is investigated for a 4-hole orifice with module m = 0.25 installed in the pipeline with an internal diameter of 50 mm. A detailed numerical simulation was performed for the turbulence models: k-ε-realizable and k-ω-BSL. The novelties of the research include model validation by comparing the results of numerical studies with the experiment conducted in the area of...
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Effects of subfilter velocity modelling on dispersed phase in LES of heated channel flow
PublikacjaA non-isothermal turbulent flow with the dispersed phase is modelled using the Large Eddy Simulation (LES) approach for fluid, one-way coupled with the equations of point-particle evolution. The channel is heated at both walls and isoflux boundary conditions are applied for fluid. Particle velocity and thermal statistics are computed. Of particular interest are the r.m.s. profiles and the probability density function of particle...
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Collection Efficiency in Narrow Electrostatic Precipitators with a Longitudinal or Transverse Wire Electrode
PublikacjaRecently narrow electrostatic precipitators (ESPs) have become a subject of interest because of their possible application in diesel engine exhaust systems. In this work, results of particle collection efficiency measurements in narrow electrostatic precipitators for negative and positive dc voltage polarity are presented. The ESP usedin this work was a parallelepiped equipped with wire discharge electrode and two collecting plate-electrodes....
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Wpływ warunków hydraulicznych w sieci wodociągowej na wtórne zanieczyszczenie wody = Effect of hydraulic conditions in the water distribution system on the secondary water pollution
PublikacjaCelem badań jest próba empirycznego wykazania wpływu zmian prędkości i czasu przebywania wody w przewymiarowanej sieci wodociągowej na wtórne jej zanieczyszczenie. Podstawą analizy są pomiary hydrauliczne wykonane podczas realizacji płukania rurociągów żeliwnych D=100 mm oraz badania laboratoryjne popłuczyn w zakresie suchej pozostałości, w tym zawartości związków żelaza. Każdą pobraną próbkę popłuczyn z hydrantów poddano szczegółowej...
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Comparison of heat transfer characteristics in surface cooling using microjets with water, ethanol and HFE7100 as test fluids
PublikacjaAccurate control of cooling parameters is required in ever wider range of technical applications. It is known that reducing the dimensions of the size of nozzle leads to an increase in the economy of cooling and improves its quality. Present study describes research related to the design and construction of the nozzles and microjet study, which may be applied in many technical applications such as in metallurgy, electronics, etc....
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Experimental validation of pressure drop models during flow boiling of R134a – effect of flow acceleration and entrainment
PublikacjaA crucial step to assure proficient work of power and process apparatus is their proper design. A wide array of those devices operates within boiling or condensation of the working fluid to benefit from high heat transfer rates. Two-phase flows are associated with high heat transfer coefficients because of the latent heat of evaporation and high turbulence level between the liquid and the solid surface. Predicting heat transfer...
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Numerical analysis of the ostiomeatal complex aeration using the CFD method
PublikacjaWe aimed to analyse ostiomeatal complex (OMC) aeration using the computational fluid dynamics (CFD) method of simulation based on human craniofacial computed tomography (CT) scans. The analysis was based on CT images of 2 patients: one with normal nose anatomy and one with nasal septal deviation (NSD). The Reynolds-Average Simulation approach and turbulence model based on linear eddy viscosity supplemented with the two-equation...
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Parametric Study on a Performance of a Small Counter-Rotating Wind Turbine
PublikacjaA small Counter-Rotating Wind Turbine (CRWT) has been proposed and its performancehas been investigated numerically. Results of a parametric study have been presented in this paper.As parameters, the axial distance between rotors and a tip speed ratio of each rotor have been selected.Performance parameters have been compared with reference to a Single Rotor Wind Turbine (SRWT).Simulations were carried out with Computational Fluids...
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Shaping the City Responding to Climate Change – Concept of Development of the Right Bank of the Vistula River in Toruń, Poland,
PublikacjaThe problems of cities of the 21st century are caused by anthropogenic oppression of the environment, through the growth of economic activity and continuous urbanisation, and taking away ecologically important open areas and biologically active areas. Increasingly frequent and sudden rains, strong winds, turbulence and rising world water levels are some of the consequences of climate change that have a direct impact on the functioning...
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Maxillary sinus aeration analysis using computational fluid dynamics
PublikacjaThe maxillary sinus aeration using the computational fluid dynamics (CFD) method based on individual adult patients’ computed tomography (CT) scans were analyzed. The analysis was based on CT images of 4 patients: one with normal nose anatomy and three with nasal septal deviation (NSD) and concha bullosa (CB). The CFD simulation was performed using the Reynolds-Average Simulation approach and turbulence closure based on linear...
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Investing in wine, precious metals and G-7 stock markets – A co-occurrence analysis for price bubbles
PublikacjaThis paper used the GSADF test to determine the periods defined in this paper as price bubbles in the three markets studied, i.e. the investment wine market, precious metal market and national stock market indices of G-7 countries. The results obtained enabled the calculation of the values of the phi correlation coefficients, which served the research objective of assessing the co-occurrence of price bubbles in the markets analysed....
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Full-scale CFD simulations for the determination of ship resistance as a rational, alternative method to towing tank experiments
PublikacjaResults of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method...
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COMPARISON OF HEAT TRANSFER CHARACTERISTICS IN SURFACE COOLING WITH BOILING MICROJETS OF WATER, ETHANOL AND HFE7100
PublikacjaThe basis of microjet technology is to produce laminar jets which when impinging the surface have a very high kinetic energy at the stagnation point. Boundary layer is not formed in those conditions, while the area of film cooling has a very high turbulence resulting from a very high heat transfer coefficient. Applied technology of jet production can result with the size of jets ranging from 20 to 500μm in breadth and 20 to 100μm...
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Contemporary and Conventional Passive Methods of Intensifying Convective Heat Transfer—A Review
PublikacjaThe ever-increasing demand for effective heat dissipation and temperature control in industrial and everyday applications highlights a critical research problem. The need for development is not only in terms of providing thermal comfort to humans but also forms the basis for the efficient operation of machines and equipment. Cooling of industrial machinery and household electronic equipment is a crucial element in any manufacturing...
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Multi-fidelity aerodynamic design trade-off exploration using point-by-point Pareto set identification
PublikacjaAerodynamic design is inherently a multi-objective optimization (MOO) problem. Determining the best possible trade-offs between conflicting aerodynamic objectives can be computationally challenging when carried out directly at the level of high-fidelity computational fluid dynamics simulations. This paper presents a computationally cheap methodology for exploration of aerodynamic design trade-offs. In particular, point-by-point...
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Sustainable Management of Food Wastes Through Cavitation-Assisted Conversion into Value-Added Products
PublikacjaMore than 30% of worldwide food consumption is thrown out as food wastes causing serious environmental, economic, and social problems. Therefore, it is required to develop sustainable food waste management methods leading to an enhancement in social and economic benefits and mitigation of environmental impacts. Anaerobic digestion can be regarded as one of those effective methods that can be employed for the conversion of food...
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Co-simulation strategy of transient CFD and heat transfer in building thermal envelope based on calibrated heat transfer coefficients
PublikacjaThe paper presents a strategy to develop a fully transient numerical model of a heat transfer in building, using a transient CFD model of indoor air and a thermal envelope model, running in a co-simulation. The strategy relies on the utilization of RANS with a high-Re turbulence model and a wall function, which enables to use a coarse computational mesh limiting the computational time. Since wall functions give invalid heat transfer...
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Fast Low-fidelity Wing Aerodynamics Model for Surrogate-Based Shape Optimization
PublikacjaVariable-fidelity optimization (VFO) can be efficient in terms of the computational cost when compared with traditional approaches, such as gradient-based methods with adjoint sensitivity information. In variable-fidelity methods, the directoptimization of the expensive high-fidelity model is replaced by iterative re-optimization of a physics-based surrogate model, which is constructed from a corrected low-fidelity model. The success...
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Koncepcje zarządzania współczesnym uniwersytetem
PublikacjaRozprawa koncentruje się na poszukiwaniu nowych koncepcji zarządzania współczesnym uniwersytetem. Problematykę podjęto ze względu na to, że masowość kształcenia i chroniczne niedofinansowanie nauki i szkolnictwa wyższego z jednej strony, a turbulencja otoczenia oraz związane z niąrosnące oczekiwania społeczne z drugiej powodują, że uczelnie są zmuszone do poszukiwań nowych rozwiązań w zakresie organizacji i zarządzania. Celem rozprawy...
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CO2 capture using steam ejector condenser under electro hydrodynamic actuator with non-condensable gas and cyclone separator: A numerical study
PublikacjaThe concept for condensation of steam and CO2 separation in a negative CO2 emission gas power plant involves the utilization of a steam ejector condenser (SEC) for direct-contact condensation of vapor with inert gas (CO2) on a spray of subcooled liquid, integrated with a separator to produce pure CO2. Due to the increasing diffusion resistance and reduced convective heat transfer between the steam and subcooled water phases...
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Experimental and numerical study of thermal and electrical potential of BIPV/T collector in the form of air-cooled photovoltaic roof tile
PublikacjaAmong renewable energy sources, Building-Integrated Photovoltaic/Thermal (BIPV/T) systems are gaining increasing interest. To improve their economic competitiveness, technologies that increase their efficiency are searched for. The paper is devoted to evaluating the impact of various air-cooling configurations on the thermal and electrical performance of a photovoltaic roof tile. A numerical model of the own experimental system...
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RANS-based design optimization of dual-rotor wind turbines
PublikacjaPurpose An improvement in the energy efficiency of wind turbines can be achieved using dual rotors. Because of complex flow physics, the design of dual-rotor wind turbines (DRWTs) requires repetitive evaluations of computationally expensive partial differential equation (PDE) simulation models. Approaches for solving design optimization of DRWTs constrained by PDE simulations are investigated. The purpose of this study is to determine...
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Scale effect in the self-propulsion prediction for Ultra Large Container Ship with contra-rotating propellers
PublikacjaThis article addresses the problem of the scale effect for an Ultra Large Container Ship (ULCS) with a novel twin-crp-pod propulsion system. Twin-crp-pod steering-propulsion arrangement is an innovative solution that gains from three well-known systems: twin-propeller, contra-rotating propellers and pod propulsors. It is expected that applying the twin-crp-pod system to the analysed Ultra Large Container Ship will increase propulsion...
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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators
PublikacjaThe main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal...
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Numerical simulation of cold flow and combustion in a swirl stabilized combustor
PublikacjaA numerical simulation model was developed to investigate the cold flow and combustion using Ansys FLUENT 2021R1. The governing equations were solved using the pressure-based method, and pressure–velocity coupling was performed using the SIMPLE method. To model the turbulent process, the RSM model was used. Non-premixed model is chosen to solve the chemical kinetics between fuel and oxigen. Radiation heat transfer was calculated...