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Search results for: COMPUTATIONAL FLUID DYNAMIC THERMAL MODELING
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Spatial aspects of urban air quality management: Estimating the impact of micro-scale urban form on pollution dispersion
PublicationUrban planning and design solutions affect urban ventilation conditions, thus mitigating the effects of atmospheric pollution. However, these findings are not being implemented in the planning practice to a sufficient extent, partly due to the lack of specific guidelines. Moreover, many urban air quality monitoring (AQM) sites have low represnentativeness and thus do not provide comprehensive data for effective urban air pollution control...
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Thermal ablation modeling via the bioheat equation and its numerical treatment
PublicationThe phenomenon of thermal ablation is described by Pennes’ bioheat equation. This model is based on Newton’s law of cooling. Many approximate methods have been considered because of the importance of this issue. We propose an implicit numerical scheme which has better stability properties than other approaches.
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Design and testing of a radial-axial microturbine for domestic applications
PublicationIn the paper presented is a new design of the radial-axial microturbine of 3-4kW capacity for operation with ethanol as working fluid
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Problem of proper decomposition and initialization of acoustic and entropy modes in a gas affected by the mass force
PublicationThe relations connecting perturbations specific for acoustic and entropy modes in an accelerated fluid or in a fluid affected by constant mass force, are derived. They allow to decompose the total vector of perturbations and the overall energy into acoustic and non-acoustic parts uniquely at any instant. In order to do this, three quantities are required, for example total perturbations in entropy, pressure and velocity. The evaluations...
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Time Domain Modeling of Propeller Forces due to Ventilation in Static and Dynamic Conditions
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On dynamic modeling of piezomagnetic/flexomagnetic microstructures based on Lord–Shulman thermoelastic model
PublicationWe study a time-dependent thermoelastic coupling within free vibrations of piezomagnetic (PM) microbeams considering the flexomagnetic (FM) phenomenon. The flexomagneticity relates to a magnetic field with a gradient of strains. Here, we use the generalized thermoelasticity theory of Lord–Shulman to analyze the interaction between elastic deformation and thermal conductivity. The uniform magnetic field is permeated in line with...
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Tilting pad thrust bearing with novel material selection - experimental comparison of low and medium speed operation
PublicationThe advances in material engineering led to the development of hard carbon based coatings applied in numerous applications in order to prevent or minimize wear of the parts in contact. With Triondur® coatings, the bearing company Schaeffler has succeeded in halving the friction losses in the valve trains of passenger cars. The coatings are optimized for high abrasive wear protection and low sliding friction moments. Altogether...
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Effect of applied standard wood machining fluid on colour and chemical composition of the machined wood surface
PublicationAppropriate monitoring of wood machining processes is a key issue to ensure the expected quality of the processed wood, expected efficiency and minimize energy consumption of production processes. A new trend is the design of environmentally friendly machining fluids. In this paper, as a preliminary study in this field, the effect of applied standard wood machining fluid on changes in the colour and chemical composition of the...
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The application of magnetic fluids in sealing nodes designed for operation in difficult conditions and in machines used in sea environment
PublicationPresented in article MF seals are being researched for sea technology purposes due to their excellent tightness and low resistance of motion. These features are most valuable for ring propellers and ship's main propeller shaft. There are more reasons why technologists payf significant attention for various MFseals applications in their difficult operating conditions. For instance, an advanced pumping systems are designed with contactless...
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The application of magnetic fluids in sealing nodes designed for operation in difficult conditions and in machines used in sea environment
PublicationPresented in article MF seals are being researched for sea technology purposes due to their excellenttightness and low resistance of motion. These features are most valuable for ring propellers and ship'smain propeller shaft. There are more reasons why technologists payf significant attention for various MFseals applications in their difficult operating conditions. For instance, an advanced pumping systemsare designed with contactless...
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On Invariants of Fluid Mechanics Tensors
PublicationThis paper presents physical interpretations of the first and second invariants of tensors of fluid mechanics. Some examples of elementary applications and meanings are also given.
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On the Possibilities of Decreasing Power Loss in Large Tilting Pad Thrust Bearings
PublicationJournal Menu About this Journal Abstracting and Indexing Aims and Scope Article Processing Charges Articles in Press Author Guidelines Bibliographic Information Citations to this Journal Contact Information Editorial Board Editorial Workflow Free eTOC Alerts Publication Ethics Submit a Manuscript Table of Contents Abstract Full-Text PDF Full-Text HTML...
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Experimental research on water lubricated three layer sliding bearing with lubrication grooves in the upper part of the bush and its comparison with a rubber bearing
Publicationcomposite. Eachofitslayershasanimportantfunction.Speciallypreparedslidingsurfaceensures minimum resistance.Followingrunning-initssmoothnessbecomesveryhighandthebearingmay continue workingunder fluid lubricationregime.NBRlayerensuresbearingelasticity,goodvibration damping propertiesandinsusceptibilitytoshaftaxismisalignment.Theexternalbrasslayermakes fitting thebearingeasier. Experiment resultsoftheconductedresearchwerecomparedwiththoseforarubberbearingof similar...
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Three-dimensional CFD modeling of thermal behavior of a disc brake and pad for an automobile
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Modeling of heat and fluid flow in granular layers using high-order compact schemes and volume penalization method
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Time fractional analysis of Casson fluid with application of novel hybrid fractional derivative operator
PublicationA new approach is used to investigate the analytical solutions of the mathematical fractional Casson fluid model that is described by the Constant Proportional Caputo fractional operator having non-local and singular kernel near an infinitely vertical plate. The phenomenon has been expressed in terms of partial differential equations, and the governing equations were then transformed in non-dimensional form. For the sake of generalized...
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FAILURE OF MAGNETIC FLUID SEALS OPERATING IN WATER: PRELIMINARY CONCLUSIONS
PublicationThe article analyses properties of magnetic fluid seals installed in rotary sealing no des which operate in the utility water environment. Seals of this type have been examined as a possible solution to the problem with ship manoeuvring propulsion sealing. The present analysis bases on laboratory durability tests of magnetic fluid seals expo sed to long - term utility water loads, at different water pressures and shaft revolutions....
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Activation Energy and Inclination Magnetic Dipole Influences on Carreau Nanofluid Flowing via Cylindrical Channel with an Infinite Shearing Rate
PublicationThe infinite shear viscosity model of Carreau fluid characterizes the attitude of fluid flow at a very high/very low shear rate. This model has the capacity for interpretation of fluid at both extreme levels, and an inclined magnetic dipole in fluid mechanics has its valuable applications such as magnetic drug engineering, cold treatments to destroy tumors, drug targeting, bio preservation, cryosurgery, astrophysics, reaction kinetics,...
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Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
PublicationIn this paper, forced convection of water/EG-Al2O3 nanofluids inside horizontal stainless steel tube is studied experimentally. As base fluid served water/EG mixture of two ratios (60:50 and 50:50). Nanoparticle mass concentrations was 0.1% or and 1%. Transition and turbulent flow regimes were tested. Average heat transfer coefficient and pressure drop values were determined for nanofluids and compared to base fluids. Deterioration...
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Burn depths evaluation based on active dynamic IR thermal imaging - A preliminary study
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Computational simulations of concrete behaviour under dynamic conditions using elasto-visco-plastic model with non-local softening
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Computational simulations of concrete behaviour under dynamic conditions using elasto-visco-plastic model with non-local softening.
PublicationW artykule przedstawiono wyniki obliczeniowych symulacji zachowania betonu w warunkach dynamicznych stosując sprężysto-lepko-plastyczny model z nielokalnym osłabieniem. Wykonano obliczenia dla ściskania jednoosiowego, rozciągania jednoosiowego i zginania. Dla dużych prędkości obciążenia uwzględniono fragmentację materiału. Wyniki porównano z doswiadczeniami.
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Subcritical bifurcation of free elastic shell of biological cluster
PublicationIn this paper we will investigate symmetry-breaking bifurcation of equilibrium forms of biological cluster. A biological cluster is a two-dimensional analogue of a gas balloon. The cluster boundary is connected with its kernel by elastic links. The inside part is filled with compressed gas or fluid. Equilibrium forms of biological cluster can be found as solutions of a certain second order ordinary functional-differential equation...
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Theoretical Organic Rankine Cycle efficiency depending on different thermodynamic work variables.
PublicationOne of promising technologies of utilizing low- temperature waste heat is through ORC (Organic Rankine Cycle) system implementation. A primary objective in designing in-stallations based on such systems is to maximize the installation's work efficiency. On the other hand, ecological factors are commonly considered a natural barrier in introducing new, often very expensive technologies. Ecological effect of a potential modernization...
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WSPÓŁPRACA BLOKU GAZOWO-PAROWEGO Z OBIEGIEM ORC = Combinded power plant in cooperation with ORC
PublicationIn the paper presented is the idea of a combined gas and steam power plant cooperation with a low temperature organic Rankine cycle ORC unit. Considerations presented in the paper are accomplished for the Gorzów CHP. The intention of present analysis is heat recovery of low temperature energy and its further use in ORC cycle in order to produce electricity, without increase in fuel consumption. Waste energy is recovered from the...
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Influence of local bush wear on water lubricated sliding bearing load carrying capacity
PublicationOne of main problems concerning water-lubricated bearings is their durability. There are known cases of bearings with life time measured in decades, and some, whose refurbishment was necessary just days after start-up. Obtaining stable fluid film friction plays key role in the durability of these bearings. Unfortunately, their load-carrying capacity is limited due to water's low-viscosity. The conducted experimental...
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generation of the vorticity mode by sound in a bingham plastic
PublicationThis study investigates interaction between acoustic and non-acoustic modes, such as vorticity mode,in some class of a non-newtonian fluid called Bingham plastic. The instantaneous equations describinginteraction between different modes are derived. The attention is paid to the nonlinear effects in the fieldof intense sound. The resulting equations which describe dynamics of both sound and the vorticity modeapply to both periodic...
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Experimental investigation of domestic gas boiler fitted with ORC module
PublicationIn the paper the prototype of innovative domestic cogenerative ORC system, consisting of a conventional gas boiler and a small size axial vapour microturbines (in-house designed for ORC and the commercially available for Rankine cycle (RC)), evaporator and condenser were scrutinised. In the course of study the fluid working temperatures, rates of heat, electricity generation and efficiency of the whole system were obtained. The...
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Experimental investigation of domestic micro-CHP based on the gas boiler fitted with ORC module
PublicationThe results of investigations conducted on the prototype of vapour driven micro-CHP unit integrated with a gas boiler are presented. The system enables cogeneration of heat and electric energy to cover the energy demand of household. The idea of such system is to produce electricity for own demand or for selling it to the electric grid – in such situation the system user will became the prosumer. A typical commercial gas boiler,...
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Analysis of the radiation dose in UV-disinfection flow reactors.
PublicationTheoretical considerations devoted to the variation of UV radiation doses in flow disinfection reactors are presented. The minimal time required by the fluid to pass the reactor was determined and combined with the radiation intensity. The active zones of the reactor were determined.
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Experimental investigations on heat transfer enhancement in shell coil heat exchanger with VARIABLE Baffles GEOMETRY
PublicationThe paper presents the possibility of using passive intensification of heat transfer in the form of baffles to increase the energy efficiency of the shell and coil heat exchanger. The experiment was carried out by using a modular coil heat exchanger in the form of an electric heater. Water was used as a working fluid with constant thermal-flow parameters at the inlet of the module. It should be noted that experiments were made...
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High-temperature heat pumps – potential technology for heat recovery and production of process heat
PublicationIn the paper, the high temperature vapour compressor based heat pump with a selection of working fluids, both perspective and ecological ones, is considered. Such system is not yet commercially available on the market and in author’s opinion it has significant potential for various applications. In the presented analysis it was assumed that the heat source has a temperature of 50oC and the temperature lift is 60, 80 and 100K respectively....
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EXPERIMENTAL STUDY OF SURFACE ROUGHNESS EFFECT ONTHE RHEOLOGICAL BEHAVIOR OF MR FLUID
PublicationPaper presents the results of shear stress measurements of a commercial magnetorheological fluid using a plate-plate type geometry with a modified working surface. The purpose of the study was to determine the effect of changing the roughness of the measuring plate on the obtained shear stress results. Controlled shear rate tests and Magneto Sweep measurements were carried out for three MR fluid layer heights. The tests were...
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Nutrient transport and acquisition by diatom chains in a moving fluid
PublicationThe role of fluid motion in delivery of nutrients to phytoplankton cells is a fundamental question in biological and chemical oceanography. In the study of mass transfer to phytoplankton, diatoms are of particular interest. They are non-motile, are often the most abundant components in aggregates and often form chains, so they are the ones expected to benefit most from enhancement of nutrient flux due to dissipating turbulence....
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Management of low-temperature heat source by ORC aided by additional heat source
PublicationThe presented work is aimed at utilisation of waste heat in the manner to produce electricity in ORC installation. Therefore the precondition of the study was to use the waste heat available in the form of a stream of hot water at 90°C. Such low enthalpy heat source is rather insufficient to produce a good quality vapour to feed the ORC turbine. That was the incentive to search for the ways of increasing the temperature of the...
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Albumin–Hyaluronan Interactions: Influence of Ionic Composition Probed by Molecular Dynamics
PublicationThe lubrication mechanism in synovial fluid and joints is not yet fully understood. Nevertheless, intermolecular interactions between various neutral and ionic species including large macromolecular systems and simple inorganic ions are the key to understanding the excellent lubrication performance. An important tool for characterizing the intermolecular forces and their structural consequences is molecular dynamics. Albumin...
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Neural network simulator's application to reference performance determination of turbine blading in the heat-flow diagnostics.
PublicationIn the paper, the possibility of application of artificial neural networks to perform the fluid flow calculations through both damaged and undamaged turbine blading was investigated. Preliminary results are presented and show the potentiality of further development of the method for the purpose of heat-flow diagnostics.
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Fluid–solid interaction on a thin platelet with high-velocity flow: vibration modelling and experiment
PublicationThe paper concerns the nonlinear behaviour of a thin platelet that is streamlined in an aerodynamic tunnel. The air velocity in the aerodynamic tunnel was at 858.9 km/h or 0.7 Ma (Ma—Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound). This experiment was numerically simulated using FSI (fluid–solid interaction) tools, namely the coupling...
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Insights Into Hydrodynamics of Spinning Fluids Reactor
PublicationSpinning fluids reactor (SFR) is one of the most efficient gas-liquid contacting system with high potential of application in many fields. The unique solution of SFR is the contacting of two spinning fluids which generated centrifugal force. The aim of this study was to investigate the pressure field distribution on the inner surface of reactors dispersing element. Obtained results confirm the high heterogeneity of the field pressure...
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Comparative Study on Effects of Thermal Gradient Direction on Heat Exchange between a Pure Fluid and a Nanofluid: Employing Finite Volume Method
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TIME-DOMAIN NUMERICAL EVALUATION OF SHIP RESISTANCE AND MOTION IN REGULAR WAVES BY USING THE CFD URANS METHOD
PublicationTaking into account the International Maritime Organization's (IMO) strategy to radically reduce the...
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Should we seek further improvement of fluid film bearings - what for and how?
PublicationFluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient. Large bearings supporting shafts of huge and important rotating machines constitute a special group of fluid film bearings since the reliability of crucial systems, like for example electro-energetic system, rely on their trouble-free operation. Large thrust bearings, apart from enormous...
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Numerical Simulation of two dimensional flow past a bridge cross section
PublicationThis work presents some numerical results concerning application of CFD in civil engineering problems. Selected theoretical aspects of fluid mechanics are elucidated. In the second part of the paper a cross section of upper footbridge of the Bella Sky Hotel in Copenhagen is analysed numerically in the field of wind action.
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Pharmaceutical and forensic drug applications of chiral supercritical fluid chromatography
PublicationTHE SUPERCRITICAL FLUID IS AN EXCELLENT CHOICE AS THE CHROMATOGRAPHIC MOBILE PHASE BECAUSE IT ALLOWS RAPID SEPARATION WITH HIGH EFFICIENCY AND APPLICATIONS INVOLVING ENANTIORESOLUTION ARE COMMON. SUPERCRITICAL FLUID CHROMATOGRAPHY (SFC) IS INCREASINGLY USED FOR ANALYTICAL, SEMI-PREPARATIVE AND PREPARATIVE PURIFICATION OF CHIRAL COMPOUNDS, INCLUDING PRODUCTION OF ENANTIOMERS THAT ARE MAINLY ENCOUNTERED DURING DRUG DEVELOPMENT. SFC...
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Rotor Blade Geometry Optimisation in Kaplan Turbine
PublicationThe paper presents the description of method and results of rotor blade shape optimisation. The rotor blading constitutes a part ofturbine flow path. Optimisation consists in selection of the shape that minimises ratio of polytrophic loss. Shape of the blade isdefined by the mean camber line and thickness of the airfoil. Thickness is distributed around the camber line based on the ratio ofdistribution. Global optimisation was done...
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The calculation long-term physical field created by water flow around the ship
PublicationThe paper presents a description of the problems with fluid flow around a ship. Using the described solution of the problem were performed numerical calculations using the boundary element method. Were also presented preliminary results of the calculation of pressure fields at the bottom of the ship, taking into account the impact of the bottom.
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Comparative analysis of the theoretical models of ideal propulsor, ideal fluid brake, ideal screw propeller and ideal axial wind turbine
PublicationThe article presents a detailed discussion of four different fluid dynamics devices.These devices are presented with all relevant mathematical formulae regarding the forces, the power and the efficiency. It is demonstrated that application of the Betz theorem to axial wind turbines is not correct and it underestimates the maximujm achievable efficiency. This conclusion is supported by numerical calculations.
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Thermal cooling process by nanofluid flowing near stagnating point of expanding surface under induced magnetism force: A computational case study
PublicationThis paper is dedicated to the exam of entropy age and research of the effect of mixing nanosolid additives over an extending sheet. In this review, Newtonian nanofluid version turned into researched at the actuated appealing field, heat radiation and variable heat conductivity results. With becoming modifications, the proven PDEs are moved into popular differential situations and paintings mathematically making use of a specific...
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Experimental Determination of Limit Adhesive Shear Strtess between Solid Wall and Liquid
PublicationTheoretically slip of a fluid with respect to the solid wall should occur even at a very low velocity of motion. However theoretical analysisand some empirical data suggest that there must be a limit value of shear stress, below which the slip does not appear. A simple metyhod of this stress determination was proposed in the paper.
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Acute hypoxia diminishes the relationship between blood pressure and subarachnoid space width oscillations at the human cardiac frequency
PublicationAcute hypoxia exerts strong effects on the cardiovascular system. Heart-generated pulsatile cerebrospinal fluid motion is recognised as a key factor ensuring brain homeostasis. We aimed to assess changes in heart-generated coupling between blood pressure and subarachnoid space width oscillations during hypoxic exposure.