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    Wyświetlanie 1-12 z 12
    Tytuł:
    The experimental assessment of air supply system modification on inlet air filtration efficiency and military vehicle engine effectiveness improvement
    Autorzy:
    Dziubak, T.
    Trawiński, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/243953.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    combustion engines
    air filters
    filtration efficiency
    flow drag
    filter absorbency
    effective parameters of the engine
    mechanical efficiency
    Opis:
    Specific features of air inlet system of BWP-1 vehicle UTD-20 engine are shown. The tests results of filtration efficiency and air flow drag for BWP-1 vehicle air filter standard version are presented. The necessity of UTD-20 engine air supplying system constructional changes are proved. The inlet air filtration system for BWP-1 engine with the porous filter was proposed and performed. The characteristics of the air purification efficiency (fi=f(mp) and flow drag Delta p- f(mp) Delta p= f(Omega c) for designed air filter were determined. Absorbency of filter for air nominal stream of engine BWP-1 was specified. The designed and executed partition air filter was subjected to comparative tests on an engine test bench. The influence of modernized air filter and fuel dose increase on engine effective parameters were determined. The tests covered comparison of effective parameters (determined for maximum load) of a UTD-20 engine equipped with a standard air filter (variant 1), a modernized air filter (variant 2) and additionally, for the modernized air filter, with injection pump with fuel dose increased (variant 3). There were determined the influence the proposed changes on indicated and effective torque during engine free acceleration and its mechanical efficiency as well.
    Źródło:
    Journal of KONES; 2010, 17, 3; 79-86
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Computational study of the wake control problem
    Autorzy:
    Protas, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/279533.pdf
    Data publikacji:
    1999
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    flow control
    drag reduction
    vortex method
    Opis:
    In the paper we are concerned with the problem of flow control. We consider two-dimentional (2D) turbulent wake flows past rotating obstacles where the control objective is to minimize the drag force. Results of numerical simulations are presented which indicate that substantial drag reduction can be obtained using an open-loop algorithm. This finding is compared with available experimental data. In the second part of the paper we derive a rigorous feedback method for optimal flow control.
    W pracy badany jest problem sterowania przepływem. Rozważanyjest dwuwymiarowy turbulentny opływ obracającej się przeszkody. Celem sterowania jest minimalizacja siły oporu. Przedstawione wyniki stymulacji numerycznych dowodzą, że istotne efekty można uzyskać przy pomocy algorytmów "otwartych". Fakt ten potwierdzają również dostępne dane eksperymentalne. W drugiej części pracy sformułowany jest algorytm sprzężenia zwrotnego oparty o teorię sterowania optymalnego.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 1999, 1; 13-27
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Steady Oseen’s flow past a deformed sphere: an analytical approach
    Autorzy:
    Srivastava, D. K.
    Yadav, R. R.
    Yadav, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/280226.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    Stokes drag
    Oseen’s drag
    axially symmetric arbitrary body
    axial flow
    Opis:
    In a recent authors’ paper, the general expression of Stokes drag experienced by a deformed sphere in both longitudinal and transverse flow situations was calculated in terms of the deformation parameter up to the second order. In this paper, Oseen’s correction to the axial Stokes drag on the deformed sphere is presented by using Brenner’s formula in general, first and then applied to prolate and oblate the deformed spheroid up to the second order of the deformation parameter. Numerical values of Oseen’s correction is obtained with respect to the deformation parameter and Reynolds number. The corresponding variations are depicted in figures. Some particular cases of a needle shaped body and flat circular disk are considered and found to be in good agreement with those existing in the literature. The import ant applications are also highlighted.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2013, 51, 3; 661-673
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    3D simulation of incompressible flow around a rotating turbulator: Effect of rotational and direction speed
    Autorzy:
    Zoubai, Elhadi
    Laidoudi, Houssem
    Tlanbout, Ismail
    Makinde, Oluwole Daniel
    Powiązania:
    https://bibliotekanauki.pl/articles/27312235.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    rotating
    turbulator
    straight tube
    drag coefficient
    power number
    laminar
    flow
    Opis:
    This paper presents new results for the dynamic behaviour of fluid around a rotating turbulator in a channel. The turbulator has a propeller form which is placed inside a flat channel. The research was carried out using 3D numerical simulation. The rationale of the experiment was as follows: we put a propeller-turbulator inside a flat channel, and then we insert a water flow inside the channel. The turbulator rotates at a constant and uniform speed. The main points studied here are the effect of the presence of turbulator and its rotational direction on the flow behaviour behind the turbulator. The results showed that the behaviour of flow behind the turbulator is mainly related to the direction of turbulator rotating. Also, the studied parameters affect coefficients of drag force and power number. For example, when the turbulator rotates in the positive direction, the drag coefficient decreases in terms of rotational speed of the turbulator, while the drag coefficient increases in terms of rotational speed when the turbulator rotates in the negative direction.
    Źródło:
    Archives of Thermodynamics; 2023, 44, 2; 139--157
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flow in a skewed compound open channel with trees on a flood plain
    Autorzy:
    Fukui, Y.
    Urayama, T.
    Takamizu, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/241408.pdf
    Data publikacji:
    2003
    Wydawca:
    Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
    Tematy:
    skewed compound open channel
    trees on the flood plain
    drag force
    secondary flow
    Opis:
    In this research, the flow in a skewed compound channel with trees on the flood plain along the skewed part is studied. Three cases are assumed. Namely, 1) there are no trees on the flood plain along the main skewed part; 2) there are many trees on the flood plain set in order; and 3) there are many trees on the flood plain in disorder. In this research, 1) changes of water level and velocity in the channel; 2) the de-velopment of secondary flow as water flows downward; 3) the drag force due to the existence of trees; and 4) the changes of the river bed level in a movable bed condition are investigated. Numerical analyses using 2-D shallow water theory are also carried out to reproduce a flow in the skewed channel. As a result, the hydraulic quantities, for example water depth and the velocity cal-culated for a case setting trees in order and close together, are available in the river planning for a situation in which some of the trees were washed downstream. Such hydraulic quantities become severe for conditions in order and close to-gether in the flood. During the experiment using sand, channel beds are deformed by piling up and digging of sands or stones in various cases.
    Źródło:
    Archives of Hydro-Engineering and Environmental Mechanics; 2003, 50, 1; 3-19
    1231-3726
    Pojawia się w:
    Archives of Hydro-Engineering and Environmental Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An analytical study of couple stress fluid through a sphere with an influence of the magnetic field
    Autorzy:
    Krishna Prasad, Madasu
    Sarkar, Priya
    Powiązania:
    https://bibliotekanauki.pl/articles/2202037.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    creeping flow
    sphere
    magnetic effect
    couple stress fluid
    drag
    przepływ pełzający
    kula
    efekt magnetyczny
    Opis:
    The present work concerns to study of the steady, axisymmetric slow flow of couple stress fluid through a rigid sphere in the transverse magnetic field. Boundary conditions on the sphere surface are the zero couple stress condition and tangential slip condition. The stream function, vorticity vector, and pressure term are obtained. The drag acting on the sphere in the presence of MHD is calculated. Here, we graphically represented the Hartmann number, couple stress, and slip parameters effect on the drag coefficient. Some well-known results of the drag are deduced.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2022, 21, 3; 99--110
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Slowly vibrating axially symmetric bodies-transverse flow
    Autorzy:
    Srivastava, D. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839883.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    płyn newtonowski
    przepływ osiowy
    metoda Stokesa
    Stokes drag
    axially symmetric bodies
    Newtonian fluid
    axial flow
    Opis:
    Stokes drag on axially symmetric bodies vibrating slowly along the axis of symmetry placed under a uniform transverse flow of the Newtonian fluid is calculated. The axially symmetric bodies of revolution are considered with the condition of continuously turning tangent. The results of drag on sphere, spheroid, deformed sphere, egg-shaped body, cycloidal body, Cassini oval, and hypocycloidal body are found to be new. The numerical values of frictional drag on a slowly vibrating needle shaped body and flat circular disk are calculated as particular cases of deformed sphere.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 226-250
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The effects of trailing edge blowing on aerodynamic characteristics of the NACA 0012 airfoil and optimization of the blowing slot geometry
    Autorzy:
    Yousefi, K.
    Saleh, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/949224.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    tangential and perpendicular blowing
    blowing jet width
    blowing amplitude
    lift and drag coefficients
    flow control
    Opis:
    The effects of blowing and its parameters including the jet amplitude, blowing coefficient and jet width in order to flow control was evaluated for a NACA 0012 airfoil. The flow was considered as fully turbulent with the Reynolds number of 5 · 105, and the Menter shear stress turbulent model was employed. Tangential and perpendicular blowing at the trailing edge were applied on the airfoil upper surface, and the jet widths were varied from 1.5 to 4 percent of the chord length, and the jet amplitude was also selected 0.1, 0.3 and 0.5. In the tangential blowing, the results showed that when the blowing amplitude increases, the lift- to-drag ratio rises by 15 percent, however, the smaller amounts of the blowing amplitude are more effective in the perpendicular blowing. Furthermore, when the blowing jet width rises, the lift-to-drag ratio increases continuously in the tangential blowing and decreases quasi- linear in the perpendicular blowing. In this study, the blowing jet width 3.5 and 4 percent of the chord length for the tangential blowing was selected as optimal values as well as smaller amounts of blowing jet width are more suitable for the perpendicular blowing. Finally, the lift-to-drag ratio was increased by 17 percent for the tangential blowing in the angle of attack of 18 degrees.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2014, 52, 1; 165-179
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    CFD simulations for selection of appropriate blade profile for improving energy efficiency in axial flow mine ventilation fans
    Autorzy:
    Panigrahi, D. C.
    Mishra, D. P.
    Powiązania:
    https://bibliotekanauki.pl/articles/91904.pdf
    Data publikacji:
    2014
    Wydawca:
    Główny Instytut Górnictwa
    Tematy:
    mine ventilation
    axial flow fan
    energy efficiency
    lift
    CFD
    drag
    wentylacja kopalń
    wentylator osiowy
    efektywność energetyczna
    winda
    Opis:
    Purpose This study focuses on one of the key design aspects of mine ventilation fans, i.e. the selection of an appropriate aerofoil blade profile for the fan blades in order to enhance the energy efficiency of axial flow mine ventilation fans, using CFD simulations. Methods Computational simulations were performed on six selected typical aerofoil sections using CFD code ANSYS Fluent 6.3.26 at angles of attack varying from 0 to 21 at an interval of 3 and at Reynolds number Re = 3 × 106, and various aerody-namic parameters, viz. coefficients of lift (Cl) and drag (Cd) as a function of angle of attack (α) were determined to assess the efficiency of the aerofoils. Results The study revealed that the angle of attack has a significant effect on the lift and drag coefficients and stall condition oc-curred at α values of 12 and 15 in most of the aerofoils. Based on the criterion of higher lift to drag ratio (Cl/Cd), a blade profile was chosen as the most efficient one for mine ventilation fans. Practical implications This study forms a basis for selecting appropriate blade profiles for the axial flow fans used for ventilation in mining industry. Originality/ value The application of an appropriate aerofoil blade profile will impart energy efficiency to the mine ventilation fans and thereby result in energy saving in mine ventilation.
    Źródło:
    Journal of Sustainable Mining; 2014, 13, 1; 15-21
    2300-1364
    2300-3960
    Pojawia się w:
    Journal of Sustainable Mining
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Slip flow of a sphere in non-concentric spherical hypothetical cell
    Autorzy:
    Krishna-Prasad, Madasu
    Powiązania:
    https://bibliotekanauki.pl/articles/1839769.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    Stokes flow
    rigid sphere
    non-concentric
    drag force
    slip condition
    przepływ Stokesa
    siła tarcia
    współczynnik poślizgu
    współczynnik korekcji
    Opis:
    Slow axisymmetric flow of an incompressible viscous fluid caused by a slip sphere within a non-concentric spherical cell surface is investigated. The uniform velocity (Cunningham’s model) and tangential velocity reaches minimum along a radial direction are imposed conditions at the cell surface (Kvashnin’s model). The general solution of the problem is combined using superposition of the fundamental solution in the two spherical coordinate systems based on the centers of the slip sphere and spherical cell surface. Numerical results for the correction factor on the inner sphere are obtained with good convergence for various values of the relative distance between the centers of the sphere and spherical cell, the slip coefficient, and the volume fraction. The obtained results are in good agreement with the published results. The effect of concentration is more in the Cunningham’s model compared to the Kvashnin’s model. The wall correction factor on the no-slip sphere is more compared to that of a slip sphere. The correction factor on the slip sphere is more than that of a spherical gas bubble.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2020, 19, 3; 59-70
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Drag force of a porous particle moving axisymmetrically in a closed cavity of micropolar fluid
    Autorzy:
    Madasu, Krishna Prasad
    Powiązania:
    https://bibliotekanauki.pl/articles/122694.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
    Tematy:
    micropolar fluid
    Stokes flow
    sphere
    concentric
    drag force
    płyn mikropolarny
    prawo Stokesa
    siła tarcia
    siła hydrodynamiczna
    przepływ pełzający
    Opis:
    The present paper deals with the problem of an incompressible axisymmetric creeping flow caused by a porous spherical particle in a spherical cavity filled with micropolar fluid. Depending on the kind of cell model, appropriate boundary conditions are used on the surface of sphere and spherical cavity. Drag force on the porous particle in the presence of a cavity is calculated to determine the correction factor to the Stokes law. A general expression for the hydrodynamic force acting on the porous sphere and, hence, for the wall correction factor of the sphere are obtained. The special cases of the porous sphere in viscous fluid, zero permeability solid sphere in micropolar fluid and viscous fluid are obtained in open and closed cavity respectively.
    Źródło:
    Journal of Applied Mathematics and Computational Mechanics; 2019, 18, 4; 41-51
    2299-9965
    Pojawia się w:
    Journal of Applied Mathematics and Computational Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical computation of low Reynolds number viscous flow past bluff bodies
    Autorzy:
    Tarafder, Md. Shahjada
    Mursaline, Miad Al
    Powiązania:
    https://bibliotekanauki.pl/articles/1839825.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    przepływ
    płyn lepki
    liczba Reynoldsa
    współczynnik oporu
    viscous flow
    low Reynolds number
    SIMPLE algorithm
    circular cylinder
    square cylinder
    drag coefficient
    Opis:
    This article presents a two-dimensional steady viscous flow simulation past circular and square cylinders at low Reynolds numbers (based on the diameter) by the finite volume method with a non-orthogonal body-fitted grid. Diffusive fluxes are discretized using central differencing scheme, and for convective fluxes upwind and central differencing schemes are blended using a ‘deferred correction’ approach. A simplified pressure correction equation is derived, and proper under-relaxation factors are used so that computational cost is reduced without adversely affecting the convergence rate. The governing equations are expressed in Cartesian velocity components and solution is carried out using the SIMPLE algorithm for collocated arrangement of variables. The mesh yielding grid-independent solution is then utilized to study, for the very first time, the effect of the Reynolds number on the separation bubble length, separation angle, and drag coefficients for both circular and square cylinders. Finally, functional relationships between the computed quantities and Reynolds number (Re) are proposed up to Re = 40. It is found that circular cylinder separation commences between Re= 6.5-6.6, and the bubble length, separation angle, total drag vary as Re, Re-0.5, Re-0.5 respectively. Extrapolated results obtained from the empirical relations for the circular cylinder show an excellent agreement with established data from the literature. For a square cylinder, the bubble length and total drag are found to vary as Re and Re-0.666, and are greater than these for a circular cylinder at a given Reynolds number. The numerical results substantiate that a square shaped cylinder is more bluff than a circular one.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 133-157
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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