Wyniki wyszukiwania - Biblioteka Nauki

1

Przepływomierz strumienia masy powietrza w kanale prostokątnym

100%

Stańda J. , Górecki J. , Andruszkiewicz A. , Kubas K.

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tom R. 7, nr 7-8

46-49

PL

Opis budowy i analiza dokładności przepływomierza do pomiaru strumienia masy powietrza w kanale o przekroju prostokątnym. W przepływomierzu zastosowano rurki uśredniające ciśnienie całkowite; może on być stosowany np.w układach transportu powietrza podmuchowego w instalacjach kotłowych lub w kanałach wentylacyjnych.

EN

A paper presents description of design and analysis of the flowmeter accuracy used to the measurement of the air mass stream in the channel with rectangular cross-section. There have been used the averaging pipes of the total pressure in the flowmeter. Flowmeter to be presented can be used, for example, in the transportation systems of the blast air in the boiler installations or in the ventilating ducts.

2

Grawitacyjny spływ wody w kanałach prostokątnych wymiennika ciepła

75%

Bednarski J. , Rajski K.

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tom R. 48, nr 12

16--17

PL

W artykule przedstawiono proces grawitacyjnego spływu wody w prostokątnych kanałach zraszanego wymiennika ciepła. Omówiono trzy podstawowe rodzaje takiego przepływu dwufazowego. Występujące zjawisko opisano za pomocą równania różniczkowego cząstkowego wraz z odpowiednimi warunkami brzegowymi. Omówiono wyniki przeprowadzonych obliczeń numerycznych. Na ich podstawie opracowano korelacje pozwalające określić grubość filmu wodnego oraz jego prędkość średnią w zależności od występującego strumienia objętościowego wody oraz od jej lepkości dynamicznej.

EN

The paper discusses process of gravity -driven water flow in the rectangular channels of the plate-type sprinkled heat exchanger. The three basic types of such two-phase flow have been presented. The occurring phenomenon has been described by the partial differential equation with appropriate boundary conditions. The results of the numerical calculations have been discussed. The correlations for determining the average speed and the thickness of the water film (depending on the volume flow and the dynamic viscosity of water) have been obtained.

3

A simplifed approach for the evaluation of groundwater fow in stream–aquifer interaction

75%

Saxena M. , Singh R. K.

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tom Vol. 69, no. 1

231--241

EN

Stream–aquifer interaction process plays an important role in modulating food wave propagation in a channel. The most elementary understanding of stream–aquifer interaction can be interpreted by the fux direction between a surface water body and the underlying aquifer. At the time of foods, stream stage rises, and the water gets infltrated into the aquifer, and this process gets reversed at the time when the stream stage gets declined. Therefore, an integrated mechanism between the surface and subsurface fows is particularly important for models, where the response of the system is based on simultaneous interactions between these two major fow domains. In this study, numerical simulation of a food wave has been demon strated considering stream–aquifer interaction. The calibration has been executed on a hypothetical food event accessed by routing a known stage hydrograph for a channel reach having a rectangular cross section which fully penetrates the adjoining aquifer given by Zitta and Wiggert (Water Resour Res 7:1341–1345, 1971). A simplifed mathematical approach, based on Darcy’s law, has been presented here for the solution of groundwater fow equations. The results obtained from the adopted procedure are also compared with the solution proposed by Zitta and Wiggert in 1971. The NSE and RMSE (m3 /s) estimate assessed for the simulated hydrographs using the proposed methodology with respect to the procedure adopted by Zitta and Wiggert (Water Resour Res 7:1341–1345, 1971) is 0.9983 and 0.8544, respectively. Therefore, the use of Simpson’s (3/8)- rule is not suggestible due to its complicated calculation and its sensitivity, and it is better to use the proposed simplifed approach for the evaluation of lateral fow.

4

Analytical solutions of heat transfer for laminar flow in rectangular channels

63%

Rybiński W. , Mikielewicz J.

Archives of Thermodynamics

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2014

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tom Vol. 35, no. 4

29--42

EN

The paper presents two analytical solutions namely for Fanning friction factor and for Nusselt number of fully developed laminar fluid flow in straight mini channels with rectangular cross-section. This type of channels is common in mini- and microchannel heat exchangers. Analytical formulae, both for velocity and temperature profiles, were obtained in the explicit form of two terms. The first term is an asymptotic solution of laminar flow between parallel plates. The second one is a rapidly convergent series. This series becomes zero as the cross-section aspect ratio goes to infinity. This clear mathematical form is also inherited by the formulae for friction factor and Nusselt number. As the boundary conditions for velocity and temperature profiles no-slip and peripherally constant temperature with axially constant heat flux were assumed (H1 type). The velocity profile is assumed to be independent of the temperature profile. The assumption of constant temperature at the channel’s perimeter is related to the asymptotic case of channel’s wall thermal resistance: infinite in the axial direction and zero in the peripheral one. It represents typical conditions in a minichannel heat exchanger made of metal.

5

Algorytm wyznaczania współczynnika Coriolisa przepływów laminarnych w kanałach prostokątnych metodą elementów brzegowych

63%

Teleszewski T. J.

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tom z. 59, nr 4

131--141

PL

W publikacji wyznaczono zależność współczynnika Coriolisa przepływów laminarnych w przewodach prostokątnych całkowicie wypełnionych płynem w zależności od stosunku wysokości do podstawy kanału. Pola prędkości zostały wyznaczone metodą elementów brzegowych (MEB). W celu wykonania symulacji napisano autorski program komputerowy LaminarFlow1D oraz przeprowadzono walidację metody na podstawie znanych rozwiązań teoretycznych.

EN

The subject of the presented elaboration is the application of the boundary integral method to calculating Coriolis coefficient (kinetic energy coefficients) driven unidirectional laminar flow in rectangle ducts. The results of calculations the Coriolis coefficient of unidirectional flow through circle pipes with comparisons of numeric solutions with accessible in the literature with analytic solutions showing the satisfactory exactitude and the efficiency the method boundary integral equations to the solution this class of problems of flow in technical uses.

6

Effects of the porous boundary and inclined magnetic field on MHD flow in a rectangular duct

63%

Chutia M.

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tom Vol. 19, nr 4

33--44

EN

In this work, a steady two dimensional MHD flow of a viscous incompressible fluid through a rectangular duct under the action of an inclined magnetic field with a porous boundary has been investigated. The coupled partial differential equations are transformed into a system of algebraic equations using the finite difference method and are then solved simultaneously using the Gauss Seidal iteration method by programming in Matlab software. Numerical solutions for velocity, induced magnetic field and current density lines are obtained and analyzed for different values of dimensionless parameters namely suction/injection parameter (S), Hartmann number (M) and inclination angle (θ) and are presented graphically.