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    Wyświetlanie 1-8 z 8
    Tytuł:
    The Simultaneous Occurrence of Logarithmic and S-Shaped Velocity Profiles in Gravel-Bed River Flows
    Autorzy:
    Franca, M. J.
    Lemmin, U.
    Powiązania:
    https://bibliotekanauki.pl/articles/241179.pdf
    Data publikacji:
    2009
    Wydawca:
    Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
    Tematy:
    field measurements
    gravel-bed river flows
    velocity profiles
    Opis:
    Based on Acoustic Doppler Velocity Profiler (ADVP) field measurements, we discuss velocity profiles observed in two shallow gravel-bed rivers with low relative submergence. In these flows, log-shaped profiles and s-shaped profiles simultaneously exist, indicating the possibility of 3D flow inside the roughness layer. A quasi-2D layer is generally found in an intermediate region of the flow above the roughness layer. Therefore a best-fit log-law approach may lead to estimates of a roughness parameter which are reasonably correlated with the local flow resistance. However, above a certain limit of the ratio roughness/water depth (∼0.6 from our measurements), the velocity distribution in the lower regions predominantly corresponds to an s-shaped profile.
    Źródło:
    Archives of Hydro-Engineering and Environmental Mechanics; 2009, 56, 1-2; 29-41
    1231-3726
    Pojawia się w:
    Archives of Hydro-Engineering and Environmental Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Integrated Approach of Profi le Studies for Surface Water Velocity on a Steep Slope in a Rectangular Channel
    Autorzy:
    Ayalew, Abebe Temesgen
    Koshuma, Abera Ermias
    Ayele, Mesfi n Amaru
    Dirate, Democracy Dilla
    Powiązania:
    https://bibliotekanauki.pl/articles/2181750.pdf
    Data publikacji:
    2022
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    fluid mechanics
    velocity profiles
    rectangular channel
    Pitot tube
    Acoustic Doppler Velocitymeter
    ADV
    Opis:
    The flow velocity of water and its accurate surface profile estimation is important parameter as changes in climate increases the uneven rainfall patterns causing flood in downstream. It is important to know the velocity profile in steep open channel flows for solving the soil erosion, flooding and sediment transport problems in rivers or streams on steep slopes. A fixed bed laboratory experiment for a rectangular channel with steep slope is conducted to find the velocity profiles and surface profiles at different sections. Velocity profiles are presented at different sections in rectangular channel with steep slope. The outcome of the laboratory based experimental investigation shows that the velocity and surface profiles are influenced by the depth of flow of water and channel bed slope respectively.
    Źródło:
    Advances in Science and Technology. Research Journal; 2022, 16, 2; 74--80
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental research on velocity profiles in selected flow systems
    Autorzy:
    Kabaciński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933977.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Gdańska
    Tematy:
    velocity profiles
    air flow measurement
    closed conduits
    automated test stand
    differential pressure flowmeter
    Opis:
    A problem of measuring of velocity profiles with the use of a fully automated test stand is presented in this paper. Due to the installed measurement equipment and various software alternatives it is possible to assess the inlet effect and distribution of velocities in the vicinity of averaging Pitot tubes in order to determine the phenomena occurring in their vicinity (recirculation, main stream direction) and verify the numerical models of turbulence. Due to the stream recirculation in the vicinity of the probes tested in a wind tunnel, a two-way probe was used instead of a Pitot tube. A linear module with a stepper motor formed an integral part of the measurement system whereby it was possible to determine the position of the measurement probe with a precision of 0.1mm. The measuring anemometer location, the possibility of adjusting the stream mean velocities and data acquisition were established by means of an original program. As far as the research in pipelines is concerned - the resulting characteristics allow the uncertainty of measurement to be precisely determined, which should be accounted for during the determination of air fluxes at locations which are not included in the technical documentation of a flowmeter.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2012, 16, 3-4; 185-201
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparing selected parameters of a two-dimensional turbulent free jet on the basis of experimental results, digital simulations, and theoretical analyses
    Autorzy:
    Skotnicka-Siepsiak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/298451.pdf
    Data publikacji:
    2017
    Wydawca:
    Uniwersytet Warmińsko-Mazurski w Olsztynie
    Tematy:
    2D free jet
    turbulent jet
    CFD
    spreading rate
    velocity profiles
    Coanda effect
    Opis:
    The presented experimental and digital examinations of a two-dimensional turbulent free jet are a first phase of in the study of the Coandă effect and its hysteresis. Additionally, basing on theoretical analyses, selected results for a turbulent jest have been also mentioned, considering theoretical assumptions for the wall layer. As the result, on the basis of experimental, digital, and analytical methods, a review of characteristic jet properties has been prepared, which includes a jet spreading ratio, its cross and longitudinal sections, and turbulence level. The jet spreading radio has been expressed as a non-linear function of the x : b relative length.
    Źródło:
    Technical Sciences / University of Warmia and Mazury in Olsztyn; 2017, 20(1); 31-48
    1505-4675
    2083-4527
    Pojawia się w:
    Technical Sciences / University of Warmia and Mazury in Olsztyn
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Parametry przepływowe wypełnienia porowatego ze spienionej stali
    Flow parameters of steel foam porous packing
    Autorzy:
    Dyga, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/2070875.pdf
    Data publikacji:
    2010
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    piana stalowa
    przepuszczalność
    współczynnik bezwładności
    profil prędkości
    steel foam
    permeability
    inertia coefficient
    velocity profiles
    Opis:
    W pracy przedstawiono wyniki badań doświadczalnych oraz numerycznych, prowadzonych w celu poznania parametrów przepływowych wypełnienia porowatego ze spienionej stali. Analiza wyników badań pozwoliła określić wartość przepuszczalności i współczynnika bezwładności badanej piany stalowej. Stwierdzono, że wielkości te są różne dla gazu i cieczy oraz zależą od prędkości płynu. Na drodze numerycznej wykazano, że długość strefy stabilizacji przepływu jest nie większa niż kilka średnic pora.
    The paper presents results of experimental and numerical studies dealing with the identification of flow parameters of steel foam porous packing. The analysis of experimental results allowed one to determine a value of permeability and inertia coefficient for steel foam tested. It was stated that these parameters are different for gas and liquid and depended on fluid velocity. The numerical calculation proved that a length of flow stabilization region is not larger that several diameters of pores.
    Źródło:
    Inżynieria i Aparatura Chemiczna; 2010, 2; 33-34
    0368-0827
    Pojawia się w:
    Inżynieria i Aparatura Chemiczna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flow averaging tube geometry improvement for K-factor stability increase
    Autorzy:
    Kabaciński, M.
    Pospolita, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/114099.pdf
    Data publikacji:
    2017
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    velocity profiles
    air flow measurement
    closed conduits
    automated test stand
    flow averaging Pitot tube
    Opis:
    Fluid flow around two-profile averaging differential pressure sensor was investigated in this paper. Research concentrated particularly on fluid movement direction and velocity over the investigated flow sensor. Analysis was conducted experimentally in low velocity wind tunnel. Because of large number of measuring points placed very close to each other, it was decided that velocity profile measurement will be performed by means of fully automated test stand. Due to a recirculation of the stream in the vicinity of the probe tested in the wind tunnel, an original two-direction probe was used. A linear module with a stepper motor formed an integral part of the measurement system. The location of the measuring probe, the possibility of adjusting stream mean velocities and data acquisition was undertaken by means of a dedicated program. The above mentioned investigation method helped to improve the metrological properties of the flowmeter applying non symmetrical probe cross-section forced air stream to be redirected in the desired direction. This modification significantly increased K-factor value and stability of air flow through the contraction of the flowmeter.
    Źródło:
    Measurement Automation Monitoring; 2017, 63, 1; 2-5
    2450-2855
    Pojawia się w:
    Measurement Automation Monitoring
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of the turbulent flow structure around a standard Rushton impeller
    Autorzy:
    Kysela, B.
    Konfršt, J.
    Fořt, I.
    Kotek, M.
    Chára, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/184917.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Rushton turbine
    mixing, ensemble-average mean velocity
    fluctuation velocity
    LDA/LDV
    PIV
    velocity profiles
    turbina Rushtona
    mieszanie
    wahanie prędkości
    PRA / LDV
    profil prędkości
    Opis:
    The velocity field around the standard Rushton turbine was investigated by the Laser Doppler Anemometry (LDA) and Particle Image Velocime try (PIV) measurements. The mean ensemble-averaged velocity profiles and root mean square values of fluctuations were evaluated at two different regions. The first one was in the discharge stream in the radial direction from the impeller where the radial flow is dominant and it is commonly modelled as a swirling turbulent jet. The validity range of the turbulent jet model was studied. The second evaluated region is under the impeller where flow seems to be at first sight rather rigorous but obtained results show nonnegligible values of fluctuation velocity.
    Źródło:
    Chemical and Process Engineering; 2014, 35, 1; 137-147
    0208-6425
    2300-1925
    Pojawia się w:
    Chemical and Process Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Group and Phase Velocity of Love Waves Propagating in Elastic Functionally Graded Materials
    Autorzy:
    Kiełczyński, P.
    Szalewski, M.
    Balcerzak, A.
    Wieja, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/177447.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    surface Love waves
    group velocity
    phase velocity
    functionally graded materials
    profiles of elastic constants
    direct Sturm-Liouville problem
    Opis:
    This paper presents a theoretical study of the propagation behaviour of surface Love waves in nonhomogeneous functionally graded elastic materials, which is a vital problem in acoustics. The elastic properties (shear modulus) of a semi-infinite elastic half-space vary monotonically with the depth (distance from the surface of the material). Two Love wave waveguide structures are analyzed: 1) a nonhomogeneous elastic surface layer deposited on a homogeneous elastic substrate, and 2) a semi-infinite nonhomogeneous elastic half-space. The Direct Sturm-Liouville Problem that describes the propagation of Love waves in nonhomogeneous elastic functionally graded materials is formulated and solved 1) analytically in the case of the step profile, exponential profile and 1cosh2 type profile, and 2) numerically in the case of the power type profiles (i.e. linear and quadratic), by using two numerical methods: i.e. a) Finite Difference Method, and b) Haskell-Thompson Transfer Matrix Method. The dispersion curves of phase and group velocity of surface Love waves in inhomogeneous elastic graded materials are evaluated. The integral formula for the group velocity of Love waves in nonhomogeneous elastic graded materials has been established. The results obtained in this paper can give a deeper insight into the nature of Love waves propagation in elastic nonhomogeneous functionally graded materials.
    Źródło:
    Archives of Acoustics; 2015, 40, 2; 273-281
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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