Based on cavitation modelling in Laval nozzle results and experience, following problem was defined. Flowing of water turbine blade wheel outlet is the main point problem. Nowadays there a chance to model Fluent system, where solution two-phase mixtures (water-liquid water-vapour) more accurate three-phase (water-liquid, water-vapour non-condensable air) are presented. It possible use "Full model" or "Schnerr Sauer (simpler model) "Zwart-Gerber-Belamri" for this phenomenon. All models take...

Abstract Cavitation is a phenomenon with both positive and negative effects dynamic manifestations in hydraulic, food, chemical other machinery. This article deals the detection behavior of cavitation clouds water flows through rectangular cross-section convergent-divergent nozzle. was measured by methods applicable engineering practice. Pressure, flow rate, noise, vibration, amount air dissolved liquid were region recorded high-speed camera. Evaluation acquired images connection pressure...

Abstract The article deals with experimental investigation of water cavitation in the convergent-divergent nozzle rectangular cross-section. In practice, a quick and simple determination is essential, especially if it basic or generated additionally by air being sucked. Air influences formation, development size cavity area hydraulic elements. Removal reduction possible structural changes element. case suction air, necessary to find source seal it. pressure gradient, flow, oxygen content...

Control valves as important elements in hydraulic systems are used to transport liquid and gaseous media, for example, water, water vapor, hydrogen. They mainly the power engineering, chemical industry, so forth. Due their large dimensions, verification of parameters is problematic. In case flow, cavitation can occur, which characterized by noise, vibrations, or changes parameters. During incipient valve, there no noticeable characteristics. The article, therefore, deals with methodology...

Numerical simulation of dilution effect on combustion and flame properties is desirable for various industrial or scientific applications. Predicative capabilities the simplified (one- two-step) chemical kinetic mechanisms methane oxidation in highly diluted flames were evaluated basis mathematical modelling one-dimensional (axisymmetric) configuration. Profiles temperatures concentrations reactants, products intermediates premixed flat nonpremixed counterflow burning air/diluent mixture...

The methodology of determining the additional effects a liquid acting on hydrodynamic machine rotor is presented in paper. Special attention paid to force inside sealing gap. A new mathematical model derived from which evident an influence different parameters bond stiffness, mass and damping.

Cavitation is undesirable phenomenon occurring mainly in the flow of water pumps and turbines, therefore it necessary to pay attention it. The purpose explore possibility mathematical modelling cavitation using Singhal model, which solves multiphase vapour. issue can be solved taking into account non-condensable gas (air). model was selected on basis good experience dynamic changes Laval nozzle [2], [10]. This article presents two alternatives. first variant testing a for simple geometry...

The paper deals with numerical modelling of body aerodynamic drag coefficient in the transition from laminar to turbulent flow regimes, where selection a suitable model is problematic. On basic problem around simple – sphere selected computational models are tested. values obtained by simulations coefficients each compared graph dependency vs. Reynolds number for sphere. Next Strouhal evaluated, vortex shedding frequency given speed numerically and experimentally then experiment. aim specify...

The article deals with the determination of flow characteristics and loss coefficients control valve when water flows in interval operating parameters, including evaluation vapour air cavitation regime. are measured on experimental equipment subsequently determined. Data from measurements used for creating mathematical model verification results. This validation will enable application methods numerical modelling valves atypical dimensions e.g. use nuclear power industry. correct knowledge...

Mathematical modeling is applied as an effective tool for prediction of cavitation in hydraulic components and systems. A multiphase mathematical model based on the change phase between water vapor typically used to investigate flow. However, dissolved air can significantly affect cavitation. This study proposes a new approach turbulent by adding into mixture solve dynamics To clearly assess significance model, four variants are investigated (water; vapor; air; water, vapor, together). The...

The article is focused in three areas. In the first part there are analyzed adhesion forces at liquid and solid surface interface. There shown measured values of energy for different types surfaces. value decisive determining extent wettability by liquid. second points to possible negative effects partly wettable surfaces, showing susceptibility cavitation. third section describes practical aspects Under new boundary conditions bases, expressing effect forces, determined centrifugal pump...

The flow of fluids near the slide surface is analyzed in work introduction. Surface considered as partly hydrophobic, depending on energy for different types material surfaces. There point out relationship adhesion force to liquid/surface interaction. This creates a new boundary condition, from conditions. On basis assessing conditions cavitation creation, change.

Very rapid physical and chemical processes during the explosion require both quality quantity of detection devices. CFD numerical simulations are suitable instruments for more detailed determination parameters. The paper deals with mathematical modelling vented turbulent flame spread use ANSYS Fluent software. is focused on verification preciseness calculations comparing calculated data results obtained in realised experiments chamber.

The distribution of pollutants in two urban scale models (point emission source and street canyon with extensive transport) was investigated by means CO 2 laser photoacoustic spectroscopy the region atmospheric window (9–10 μm). experimental results physical modeling are a good agreement numerical calculations performed frame computational fluid dynamic (CFD) modeling. Methanol, ethanol, ozone (examples light pollutants), as well sulfur hexafluoride 1,2 dichlorethane heavy were selected on...

The theory of fluid flow in an eccentrically deposited annulus has great importance especially the design sliding bearings (axial, radial). If geometry is more complex or shaft eccentrically, then a suitable alternative for hydrostatic bearing using ANSYS Fluent, which solves general three-dimensional viscous also geometry. problem narrow gap between cylinders this paper, when inner cylinder stored with defined eccentricity. movement composed two motions (rotation, precession), i.e. rotation...

This paper evaluates the influence of radial grooves in eccentrically deposited annulus using by mathematical modeling fluid flow through each grooves. The inner cylinder (rotor) is and its movement composed two movements (rotation precession). outer stationary has In first phase defined a model flow, which then applied to 3D narrow gap with this are present several variants computational domain regard number Based on results numerical simulations evaluated basic variables such as pressure...

The paper deals with the determination of characteristic as dependence valve pressure drop on flow rate, and cavitation conditions in case water control valve. Emphasis is put utilization simple, available relationships measuring for identification basic coefficients, e.g. loss coefficient, rate coefficient factor. These coefficients are used designing pipe circuits. In this there defined methodology determining those applied to modified cone verification linear characteristic. It necessary...

This paper is focused on problem of gas behaviour at a leak from the low-pressure pipe system. During leak, leaking flammable mixed with ambient air and hazardous explosive mixture formed. Formation local critical concentrations methane-air in closed dissected space depends duration leak. Velocity propagation leaked gas, gas-air also formations these could be determined using successful verification CFD simulation experiments. The detailed numerical analysis enables to determine volume...

The paper deals with the problems of cavitation in water flow nozzle. area research is divided into two directions (experimental and numerical research). During experimental equipment nozzle under measurement basic physical quantities such as pressure volume rate are recorded. In following phase measuring noise which generated during through measured at various operating conditions pump. second part appropriate multiphase mathematical model including consideration defined. Boundary for...

Abstract The availability of reliable modeling tools and input data required for the prediction surface removal rate from lithium fluoride targets irradiated by intense photon beams is essential many practical aspects. This study motivated implementation soft X-ray (SXR) or extreme ultraviolet (XUV) lasers pulsed ablation thin film deposition. Specifically, it focused on quantitative description XUV laser-induced desorption/ablation fluoride, which a reference large band-gap dielectric...

Fluid flow in hydraulic systems, fittings, and piping causes losses due to the change of direction friction fluid. The main consequence resulting is increase overall pressure gradient circuit. paper focused on investigation valve determination resistance coefficients, definition which depends type. Methods are two types, i.e. experimental methods mathematical methods. In case methods, procedures prescribed by standards regulations must be respected. Mathematical related defining an...

The contribution deals with leakage of natural gas from domestic low-pressure piping. Spreading the leaked in confined space is and areas are defined where local hazardous concentrations formed. Mathematical CFD models provide broad overview spreading gas, dependence on elapsed time start leakage. should improve understanding distribution mixture gaseous fuels spaces, thus leads to significant reduction risk occurrence fire or explosion prevention these hazards.