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Tytuł:
Use of bubble load to interpret particle transport across the pulp-froth interface in a flotation cell
Autorzy:
Bhondayi, Clayton
Powiązania:
https://bibliotekanauki.pl/articles/1450066.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
bubble loading
entrainment
true flotation
froth flow number
dropback
Opis:
This work demonstrates the use of bubble loads to understand the transport of particles across the pulp-froth interface in a flotation cell processing an Upper Group 2 chromitite seam (UG2) ore. Bubble loads were measured on the first primary cleaner cell of an operating flotation plant using a bubble load meter with a 20mm riser diameter. A bubble load value of 10.58grams/liter was obtained. The bubble load data was used to understand, entrainment and dropback of chromite as a function of particle size. By defining terms such as froth flow number and net dropback, it was found that chromite (known to be non-floatable) was also recovered through true flotation. The entrainment of chromite was found to be predominantly in -25 μm size while +25 μm size particles were found to be floatable and highly susceptible to dropping back. Net-dropback of chromite particles was found to increase with a decrease in chromite particle size contrary to expectation. An overall froth flow number of 69% was obtained.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 1; 54-64
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Odporność na deformacje trwałe betonu asfaltowego przeznaczonego do warstwy ścieralnej z różnymi asfaltami na podstawie badania Flow Number
The resistance of asphalt concrete for wearing course with various bitumens to permanent deformation based on Flow Number Test
Autorzy:
Mejłun, Łukasz
Jaskuła, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/144703.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
Tematy:
Flow Number
odporność na deformacje trwałe
beton asfaltowy
warstwa ścieralna
resistance to permanent deformation
asphalt concrete
wearing course
Opis:
W artykule przedstawiono ocenę odporności na deformacje trwałe betonu asfaltowego AC 11S z asfaltami: drogowym 50/70, modyfikowanym 45/80-55 i wysokomodyfikowanym 45/80-80 na podstawie oceny wyników, mniej znanego w Polsce, badania Flow Number według procedury amerykańskiej. Ocenie poddano następujące parametry: wartość Flow Number (FN), skumulowane odkształcenie trwałe przy liczbie cykli wynoszącej FN i indeks FN. Dodatkowo otrzymane wyniki zostały odniesione do wymagań amerykańskich oraz porównane z wynikami badania odporności mieszanek na koleinowanie wg PN-EN 12697-22.
In the paper was presented the assessment of resistance to permanent deformation of asphalt concrete for wearing course: AC 11S with bitumens: neat bitumen 50/70, polimer-modified bitumen 45/80-55 and highly-modified bitumen 45/80-80 based on the results assessment of less-known in Poland Flow Number Test according to the American procedure. In the article following parameters were evaluated: the Flow Number (FN) value, the cumulative permanent deformation at the number of cycles of FN and the FN index. Additionally, the obtained results were referred to the American requirements and compared with wheel tracking test results according to PN-EN 12697-22.
Źródło:
Drogownictwo; 2019, 7-8; 196-202
0012-6357
Pojawia się w:
Drogownictwo
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SUPERPAVE design mixture performance evaluation using Epolene modifier for cold semi-arid climatic region of Saudi Arabia
Autorzy:
Dahim, M.A.
Mosaby, M.
El Morabet, R.
Khan, R.A.
Alqadhi, S.
Khan, N.A.
Ben Kahla, N.
Neklonskyi, I.
Borysova, L.
Powiązania:
https://bibliotekanauki.pl/articles/2175741.pdf
Data publikacji:
2021
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
SUPERPAVE
Epolene
dynamic modulus test
flow number test
indirect tensile test
badanie modułu dynamicznego
badanie liczby przepływu
pośrednia próba rozciągania
Opis:
Purpose: To evaluate the superpave design performance using Epolene (EE-2) as modifier, since SUPERPAVE design is a modified and sophisticated aspect as compared to previous mix design for asphalt mixtures. This is primarily due to the fact that superpave design mix also takes into consideration properties of materials beside asphalt. Design/methodology/approach: This study was conducted using Epolene (EE-2) as modifier in order to evaluate the performance of SUPERPAVE suitability for construction of roads in Alfaraa campus (King Khalid University) Abha, in Asir Province of Saudi Arabia. Glow number test, dynamic modulus test and indirect tensile strength test were conducted to evaluate the performance of EE-2 modifier against the control mixture. Findings: The mixture modified with EE-2 gave better performance in terms of temperature-based performance and resistance to moisture damage. Also, larger values of E*/sinφ were obtained for EE-2 modified mixture at various loading frequencies and temperature in comparison to control mixture. Research limitations/implications: The Epolene modifier successfully enhances and improves the SUPERPAVE mixture performance. Further studies are required to evaluate the performance of EE-2 modifier at much lower temperature ranges. Practical implications: The results of the study allow us to recommend the investigated asphalt mixture for applied for the construction of roads in the Alfaraa (new campus of King Khalid University), Abha, Asir province, Saudi Arabia. Originality/value: A modified asphalt mixture has been proposed that has better performance at higher and lower temperatures. The developed asphalt mixture is more resistant to moisture damage than the compared to control mixture.
Źródło:
Archives of Materials Science and Engineering; 2021, 112, 2; 49--54
1897-2764
Pojawia się w:
Archives of Materials Science and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Variable Electroconductivity and Radiation on MHD Couette Flow
Autorzy:
Ngiangia, Alalibo T.
Okechukwu, Amadi
Powiązania:
https://bibliotekanauki.pl/articles/1192671.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
MHD
Electrconductivity
Prandtl number
Grashof number
Reynolds Number
Radiation
Couette flow
Opis:
A study of Couette flow in cylindrical coordinate under the influence electroconductivity and magnetic field was carried out. Approximate solution of the governing equations and its analysis show decrease in temperature as a result of increase in radiation and Prandtl number. The study also reveals that increase in grashof number, Reynolds number, Prandtl number and electroconductivity result in an increase in velocity distribution while magnetic field increase, lead to a decrease in velocity. The shear stresses of the outer and inner cylinders at the wall of the plates and the heat flux is also determined.
Źródło:
World Scientific News; 2016, 47, 2; 241-253
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverse aspects of the three-way catalytic converter operation in the spark ignition engine
Autorzy:
Żmudka, Z.
Postrzednik, S.
Powiązania:
https://bibliotekanauki.pl/articles/242021.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
catalytic converter
conversion rate
flow resistance
local resistance number
friction number
Opis:
There are two sides of the catalyst operation: favourable and adverse. The positive side can be expressed by a conversion rate of harmful substances which is the principal parameter of catalyst work in respect of ecology. However, resistance of exhaust gas flow through the catalytic converter is also an essential problem. This is just the negative, adverse side of the converter operation. The catalytic converter can be treated as a local or linear resistance element of exhaust system. The first model, in which flow resistance generated by a catalyst is treated as local resistance, is more simplified. It is especially useful in case, when detailed constructional data of converter are unknown and the analysis of flow resistances in exhaust system is necessary. The basic measured quantity of flow resistance is pressure drop of exhaust gas within the catalyst. Next, on the basis of taken measurements also resistance number for the tested catalyst is calculated and analysed. Resistance number of the converter is calculated using Darcy model. In the second case, exhaust gas flow resistance through catalyst is treated as linear resistance with energy dissipation (linear frictional resistance) distributed linearly along way of exhaust gas flow. Friction number for the tested converter is calculated and analysed. The problem has been illustrated by the results of experimental researches of the three-way catalytic converter installed in the exhaust system of the spark ignition engine.
Źródło:
Journal of KONES; 2011, 18, 2; 509-516
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation and sensitivity analysis of turbulent heat transfer and pressure drop of Al2O3/H2O nanofluid in straight pipe using response surface methodology
Autorzy:
Fadodun, Olatomide G.
Amosun, Adebimpe A.
Salau, Ayodeji O.
Olaloye, David O.
Ogundeji, Johnson A.
Ibitoye, Francis I.
Balogun, Fatai A.
Powiązania:
https://bibliotekanauki.pl/articles/239962.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nusselt number
Reynolds number
pressure drop
response surface methodology
nanofluid
single phase flow
Opis:
In this paper, investigation of the effect of Reynolds number, nanoparticle volume ratio, nanoparticle diameter and entrance temperature on the convective heat transfer and pressure drop of Al2O3/H2O nanofluid in turbulent flow through a straight pipe was carried out. The study employed a computational fluid dynamic approach using single-phase model and response surface methodology for the design of experiment. The Reynolds average Navier-Stokes equations and energy equation were solved using k-ε turbulent model. The central composite design method was used for the response-surface-methodology. Based on the number of variables and levels, the condition of 30 runs was defined and 30 simulations were performed. New models to evaluate the mean Nusselt number and pressure drop were obtained. Also, the result showed that all the four input variables are statistically significant to the pressure drop while three out of them are significant to the Nusslet number. Furthermore, sensitivity analysis carried out showed that the Reynolds number and volume fraction have a positive sensitivity to both the mean Nusselt number, and pressure drop, while the entrance temperature has negative sensitivities to both.
Źródło:
Archives of Thermodynamics; 2020, 41, 1; 3-30
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soret and Dufour effects on MHD micropolar fluid flow over a linearly stretching sheet, through a non-Darcy porous medium
Autorzy:
Reddy, G. V. R.
Krishna, Y. H.
Powiązania:
https://bibliotekanauki.pl/articles/265236.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
przepływ magnetohydrodynamiczny
parametr magnetyczny
warstwa graniczna
MHD flow
magnetic parameter
Dufour number
Soret number
Opis:
In this paper, we discuss the Soret and Dufour effects on an MHD micropolar fluid flow over a linearly stretching sheet, through a non-Darcy porous medium, where stretching velocity of the sheet varies linearly with distance from the origin, and, temperature and concentration vary non-linearly in the boundary layer region. By suitable similarity transformations, the governing boundary layer equations are transformed to ordinary differential equations. These equations are solved by numerical computations with bvp4c along with the shooting technique method. The effects of the magnetic parameter, Soret number and Dufour number on velocity profiles, microrotation profile, heat transfer, and concentration, skin-friction, Nusselt number and Sherwood number are computed, discussed and analysed numerically and presented through tables and graphs.
Źródło:
International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 485-502
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The heat transfer and flow structure analyses of low concentration copper nanofluids in a strong magnetic field
Autorzy:
Roszko, A.
Fornalik-Wajs, E.
Powiązania:
https://bibliotekanauki.pl/articles/175547.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
nanofluids
heat transfer
flow structure
fast Fourier transform
Nusselt number ratio
thermomagnetic Rayleigh number
Opis:
Main aim of this paper was to analyze the influence of strong magnetic field on the enhancement or suppression of nanofluids transport processes. The second objective was to determine how the flow structure changed under the influence of a magnetic field. Analyzed diamagnetic nanofluids composed of distilled water and the copper nanoparticles of 40–60 nm size in three different concentrations (50, 500, and 1000 ppm). The experimental enclosure position in the magnet test section caused the most intricate interaction of the acting forces: the gravitational and magnetic buoyancy ones, and made the interpretation of results very difficult. The Nusselt number ratio and the thermomagnetic Rayleigh number were determined for heat transfer analysis, while the fast Fourier transform was performed for the nanofluid flow structure analysis. Spectral analysis for all examined nanofluids was presented. Influence of nanoparticles concentration was clearly visible, while the direct impact of magnetic field on the heat transfer and flow structure should be still investigated.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2015, 128; 29-42
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary mach numbers
Autorzy:
Anker, J. E.
Mayer, J. F.
Stetter, H.
Powiązania:
https://bibliotekanauki.pl/articles/1986683.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
preconditioning
non-reflecting boundary condition
Mach number independency
turbomachinery flow
Opis:
A preconditioned solution scheme for the computation of compressible flow in turbomachinery at arbitrary Mach numbers is presented. The preconditioning technique used is applied to a state-of-the-art explicit, time-marching Navier-Stokes code which originally was developed for compressible, high-speed turbomachinery applications. It combines the ideas of low Mach number preconditioning and artificial compressibility method into a unified approach where principally fluids with arbitrary equations of state can be simulated. As shown by the test cases presented, it allows the code to simulate flows efficiently and accurately independent of the Mach number. A description of the Navier-Stokes equations for rotating coordinate systems, along with the solution scheme and the details of the preconditioning method is given. Since turbomachinery computations are often performed on truncated domains, the solution scheme should be used in conjunction with non-reflecting boundary conditions. A change in the time-dependency of the equations due to preconditioning necessitates a modification of the boundary conditions. Thus, a derivation of the appropriate boundary conditions for the presented preconditioned scheme was performed and the resultant equations are given in this paper. The effectiveness of the new boundary conditions is demonstrated by comparing them with both boundary conditions that use the standard one-dimensional characteristic approach and the original boundary conditions for the non-preconditioned case.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 143-176
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Visualization of flow past square cylinders with corner modification
Autorzy:
Virkam, C. K.
Ravindra, H. V.
Krishnegowda, Y. T.
Powiązania:
https://bibliotekanauki.pl/articles/1819175.pdf
Data publikacji:
2020
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
flow visualization
spacing ratio
Strouhal number
wizualizacja przepływu
liczba Strouhala
Opis:
This article presents the results for flow past a square cylinder and two square cylinders of same and different size with corner modifications by varying the spacing ratio. Here, experimental work is conducted in a recirculatory channel filled with water. A set of aluminum discs made to rotate to create the flow in the test section. Motor is used to vary the speed of water. Fine aluminum powder is used as a tracer medium. It is observed that vortex shedding frequency decreases by placing second cylinder in the downstream of the first cylinder. For a similar size cylinders, the width of the eddy in the middle of the cylinders increases with increase in spacing ratio. With the increase of spacing ratio to 6, the flow past each cylinder behaves like single square cylinder. If upstream square cylinder size is smaller than the downstream square cylinder, the eddy size is reduced in between the cylinder compared to the downstream of the second cylinder. If upstream square cylinder size is bigger than the downstream square cylinder, the eddy size is larger in between the cylinder compared to the downstream of the second cylinder.
Źródło:
Journal of Mechanical and Energy Engineering; 2020, 4, 3; 285--294
2544-0780
2544-1671
Pojawia się w:
Journal of Mechanical and Energy Engineering
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:
Numerical investigation for convective heat transfer of nanofluid laminar flow inside a circular pipe by applying various models
Autorzy:
Saeed, Farqad Rasheed
Al-Dulaimi, Marwah Abdulkareem
Powiązania:
https://bibliotekanauki.pl/articles/1845502.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convective heat transfer
Reynolds number
nanofluid
single-phase flow
thermophysical properties
Opis:
The work presents a numerical investigation for the convective heat transfer of nanofluids under a laminar flow inside a straight tube. Different models applied to investigate the improvement in convective heat transfer, and Nusselt number in comparison with the experimental data. The impact of temperature dependence, temperature independence, and Brownian motion, was studied through the used models. In addition, temperature distribution and velocity field discussed through the presented models. Various concentrations of nanoparticles are used to explore the results of each equation with more precision. It was shown that achieving the solution through specific models could provide better consistency between obtained results and experimental data than the others.
Źródło:
Archives of Thermodynamics; 2021, 42, 1; 71-95
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation and sensitivity analysis of entropy generation of Al2O3/H2O nanofluid in turbulent regime using response surface methodology
Autorzy:
Fadodun, Olatomide G.
Olokuntoye, Bolanle A.
Salau, Ayodeji O.
Amosun, Adebimpe A.
Powiązania:
https://bibliotekanauki.pl/articles/240104.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
entropy production
Reynolds number
response-surface-methodology
nanofluid
single-phase flow
Opis:
This work investigates the effect of Reynolds number, nanoparticle volume ratio, nanoparticle size and entrance temperature on the rate of entropy generation in Al2O3 /H2O nanofluid flowing through a pipe in the turbulent regime. The Reynolds average Navier-Stokes and energy equations were solved using the standard k-ε turbulent model and the central composite method was used for the design of experiment. Based on the number of variables and levels, the condition of 30 runs was defined and 30 simulations were run. The result of the regression model obtained showed that all the input variables and some interaction between the variables are statistically significant to the entropy production. Furthermore, the sensitivity analysis result shows that the Reynolds number, the nanoparticle volume ratio and the entrance temperature have negative sensitivity while the nanoparticle size has positive sensitivity.
Źródło:
Archives of Thermodynamics; 2020, 41, 2; 119-146
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat transfer study from square cylinder immersed in water-based nanofluid: Effect of orientation
Autorzy:
Kaur, Jaspinder
Ratar, Jatinder Kumar
Tiwari, Anurag Kumar
Powiązania:
https://bibliotekanauki.pl/articles/2173435.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
inclined square cylinder
nanofluids
Reynolds number
Prandtl number
steady flow
regime
nanopłyn
liczba Reynoldsa
liczba Prandtla
przepływ stały
Opis:
Heat transfer study from the heated square cylinder at a different orientation angle to the stream of nanofluids has been investigated numerically. CuO-based nanofluids were used to elucidate the significant effect of parameters: Reynolds number (1–40), nanoparticle volume fraction (0.00–0.05), the diameter of the NPs (30–100 mn) and the orientation of square cylinder (0–90). The numerical results were expressed in terms of isotherm contours and average Nusselt number to explain the effect of relevant parameters. Over the range of conditions, the separation of the boundary layers of nanofluids increased with the size of the NPs as compared to pure water. NPs volume fraction and its size had a significant effect on heat transfer rate. The square cylinder of orientation angle (45) gained a more efficient heat transfer cylinder than other orientation angles. Finally, the correlations were developed for the average Nusselt number in terms of the relevant parameters for 45 orientation of the cylinder for new applications.
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 243--250
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation on the transition of fluid flow characteristics through a rotating curved duct
Autorzy:
Hasan, Mohammad Sanjeed
Islam, MD. Sirajul
Badsha, MD. Faisal
Mondal, Rabindra Nath
Lorenzini, Giulio
Powiązania:
https://bibliotekanauki.pl/articles/1839803.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
wymiana ciepła
przepływ wtórny
liczba Taylora
rotating curved duct
Taylor number
flow transition
secondary flow
heat transfer
Opis:
Time-dependent flow investigation through rotating curved ducts is utilized immensely in rotating machinery and metal industry. In the ongoing exploration, time-dependent solutions with flow transition through a rotating curved square duct of curvature ratio 0.009 have been performed. Numerical calculations are carried out for constant pressure gradient force, the Dean number Dn = 1000 and the Grashof number Gr = 100 over a wide range of the Taylor number values […] for both positive and negative rotation of the duct. The software Code:Blocks has been employed as the second programming tool to obtain numerical solutions. First, time evolution calculations of the unsteady solutions have been performed for positive rotation. To clearly understand the characteristics of regular and irregular oscillations, phase spaces of the time evolution results have been enumerated. Then the calculations have been further attempted for negative rotation and it is found that the unsteady flow shows different flow instabilities if Tr is increased or decreased in the positive or in the negative direction. Two types of flow velocities such as axial flow and secondary flow and temperature profiles have been exposed, and it is found that there appear two- to four-vortex asymmetric solutions for the oscillating flows for both positive and negative rotation whereas only two-vortex for the steady-state solution for positive rotation but four-vortex for negative rotation. From the axial flow pattern, it is observed that two high-velocity regions have been created for the oscillating flows. As a consequence of the change of flow velocity with respect to time, the fluid flow is mixed up in a great deal which enhances heat transfer in the fluid.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 3; 45-63
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pomiar kryzą segmentową strumienia medium dla małych liczb Reynoldsa
Measurement with segmental orifice of flow medium for small Reynolds numbers
Autorzy:
Mrowiec, A.
Kasprzak, D.
Powiązania:
https://bibliotekanauki.pl/articles/267014.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Tematy:
kryza segmentowa
liczba Reynoldsa
współczynnik przepływu
segmental orifice
Reynolds number
flow factor
Opis:
Podstawowym surowcem energetycznym w Polsce jest węgiel. W ostatnich latach podejmowano próby spalania koloidalnych zawiesin pyłu węglowego w oleju napędowym lub opałowym. Przy pomiarach przepływu takich zawiesin, może dochodzić do wytrącania i zalegania w układach przesyłowych osadów, co w efekcie może prowadzić do zaburzeń strumienia przepływu. Wiarygodność pomiaru tego parametru, mogą zapewnić kryzy segmentowe. W artykule zaprezentowano wyniki badań przepływowych kryz segmentowych z przytarczowym punktowym odbiorem ciśnienia różnicowego, przy niewielkich liczbach Reynoldsa oraz symulacje numeryczne dla wybranej kryzy. W badaniach jako medium wykorzystano wodę.
In Poland coal is the main energy resource. As part of the conducted research attempts were made at using suspensoids containing coal dust in gas oil and furnace oil. This leads to a reduction in NOx and SOx percentage without the need for an expensive desulphurization and dust extraction installation. However, there is a need for using cheap but reliable systems to measure the flow of the injected fuel. In real operating conditions various residues may often deposit in fuel transmission systems, which in turn can lead to flow fluctuations. Reliable flow factor measurement requirements can be met by segmental orifices. In the article, based on a research and measurement station, presented were the results of flow measurements with segmental orifices with point reception of differential pressure for small Reynolds numbers as well as numerical simulations. For the selected segmental orifice the flow factor characteristic in the function of the Reynolds number was calculated. In the research, water was used as the medium; the next stage of the research will involve the realization of the proposed solution with the use of hydraulic oil.
Źródło:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2016, 49; 75-78
1425-5766
2353-1290
Pojawia się w:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and validation of a single-jack variable Mach number nozzle in a cryogenic transonic wind tunnel
Autorzy:
Yu, Chengguo
Zhang, Zhili
Wang, Ning
Nie, Xutao
Peng, Qiang
Chen, Zhenhua
Powiązania:
https://bibliotekanauki.pl/articles/2200829.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
cryogenic
flow uniformity
single-jack nozzle
transonic wind tunnel
variable
Mach number
Opis:
The wind tunnel with variable Mach numbers controlled by a single jack is highly desired in the aerospace, automobile and building industry due to its superior controllability and working range. Decreasing the temperature of a test gas is an efficient and economical approach to achieving higher Reynolds numbers that accommodate all working statuses of test subjects, which however, brings new challenges to the wind tunnel design nowadays. This paper proposes a new design concept of a single-jack variable Mach number nozzle based on its particular cryogenic characteristics, as the nozzle is the core structure to achieve variable Mach numbers. The contours of the nozzle under different Reynolds numbers and Mach numbers are modeled and solved by an incomplete elliptic integral, followed by modification with cryogenic characteristics. A 0.3-m cryogenic wind tunnel is utilized as a validation platform for the nozzle design, resulting in designed contours being in line with the measured contours. Moreover, the root means square (RMS) deviations of Mach number 1.3 at the core position are controlled within 0.011 in low and high temperatures, which surpasses the other existing wind tunnels.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 4; 719--732
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of selected aspects of a tank gassing-up process on board liquefied petroleum gas carrier. Part I
Autorzy:
Wieczorek, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/1845464.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convective heat transfer
Reynolds number
nanofluid
single
wall
carbon
nanotube
SWCNT
laminar flow
Opis:
The paper is a thermodynamics analysis of the removal of any inert gas from the tank using the vapors of any liquefied petroleum gas cargo (called cargo tank gassing-up operation). For this purpose, a thermodynamic model was created which considers two boundary cases of this process. The first is a ‘piston pushing’ of inert gas using liquefied petroleum gas vapour. The second case is complete mixing of both gases and removal the mixture from the tank to the atmosphere until desired concentration or amount of liquefied petroleum gas cargo in the tank is reached. Calculations make it possible to determine the amount of a gas used to complete the operation and its loss incurred as a result of total mixing of both gases.
Źródło:
Archives of Thermodynamics; 2021, 42, 2; 43-58
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of convective heat transfer of single wall carbon nanotube nanofluid laminar flow inside a circular tube
Autorzy:
Saeed, Farqad Rasheed
Jasim, Marwah A.
Mahmood, Natheer B.
Jaffar, Zahraa M.
Powiązania:
https://bibliotekanauki.pl/articles/1845470.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
convective heat transfer
reynolds number
nanofluid
single
wall
carbon
nanotube
SWCNT
laminar flow
Opis:
This study presents the behavior of a single wall carbon nanotube (SWCNT)/water nanofluid for convective laminar flow inside a straight circular pipe heated by a constant heat flux. Five volume fractions of SWCNT were used to investigate their effect on the heat transfer coefficient, Nusselt number, temperature distribution and velocity field in comparison with pure water flow. One model for each property was tested to calculate the effective thermal conductivity, effective dynamic viscosity, and effective specific heat of the SWCNT/water mixture. The models were extracted from experimental data of a previous work. The outcomes indicate that the rheological behavior of SWCNT introduces a special effect on the SWCNT/water properties, which vary with SWCNT volume fraction. The results show an improvement in the heat transfer coefficient with increasing volume fraction of nanoparticles. The velocity of SWCNT/water nanofluid increased by adding SWCNT nanoparticles, and the maximum increase was registered at 0.05% SWCNT volume fraction. The mixture temperature is increased with the axial distance of the pipe but a reduction in temperature distribution is observed with the increasing SWCNT volume fraction, which reflects the effect of thermophysical properties of the mixture.
Źródło:
Archives of Thermodynamics; 2021, 42, 2; 103-119
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Numerical Study of Combined Natural and Marangoni Convection in a Square Cavity
Autorzy:
Cicek, K.
Baytas, A.
Powiązania:
https://bibliotekanauki.pl/articles/116928.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Numerical Study
Square Cavity
natural convection
Marangoni Convection
Buoyancy-Driven Flow
Thermo Capillary Flow
Navier-Stokes Equations
Rayleigh Number
Opis:
Through the aim of this study, the effects of combined buoyancy-driven flows and thermo capillary flows, which are emerged from temperature differences, on fluid flow and heat transfer numerically investigated with differentially heated side walls in a free surface square cavity. The study has been accomplished with three milestones to achieve the right solutions. For every milestone Navier-Stokes, continuity and energy equations are discretized by using finite volume method and grids with 52 x 52 control volumes. Results are presented Pr=1, Pr=7 and Pr=100. The effect of positive and negative Marangoni number on fluid flow and heat transfer at different Rayleigh number are considered and discussed.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2009, 3, 2; 173-178
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Catalytic reactor as a resistance element of ICE exhaust system
Autorzy:
Postrzednik, S.
Żmudka, Z.
Powiązania:
https://bibliotekanauki.pl/articles/242786.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
internal combustion engine
catalytic converter
pressure drop
local and linear flow resistance
resistance number
Opis:
Selected problems connected with operation of catalytic reactors are presented. Conversion rate of harmful substances is the principal parameter of catalyst work in respect of ecology. However, resistance of exhaust gas flow through the catalytic converter is also essential problem, apart from its chemical efficiency because fitting the catalyst in exhaust system alters flow characteristic of this system significantly. Catalytic converter can be treated as local or linear resistance element of exhaust system. The first model, in which flow resistance generated by a catalyst is treated as local resistance, is more simplified. Resistance number of the converter was calculated using Darcy model. In the second case, exhaust gas flow resistance through catalyst is treated as linear resistance with energy dissipation (linear frictional resistance) distributed linearly along way of exhaust gas flow. Friction number for the tested converter was calculated and analysed. The problem has been illustrated by results of experimental researches of three-way catalytic converter installed in exhaust system of spark ignition engine and its basic analysis.
Źródło:
Journal of KONES; 2007, 14, 4; 351-356
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat transfer and friction characteristics in three-side solar air heaters with the combination of multi-v and transverse wire roughness
Autorzy:
Kumar, Dhananjay
Powiązania:
https://bibliotekanauki.pl/articles/2204071.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
absorber plate
fluid flow
heat transfer
solar air heater
reynolds number
relative roughness height
Opis:
The present paper describes the experimental analysis of heat transfer and friction factor for glass protected three-side artificially roughened rectangular duct solar air heaters (SAHs) having an arrangement of multiple-v and transverse wires (top wall multi-v and two side walls transverse) under the absorber plate, and compares their performance with that of one-side roughened solar air heaters under similar operating conditions. The investigated three-side solar air heaters are characterized by a larger rate of heat transfer and friction factor as compared to one-side artificially roughened SAHs by 24–76% and 4–36%, respectively, for the identical operating parameters. The air temperature below the three-side rugged duct is by 34.6% higher than that of the one-side roughened duct. Three-side solar air heaters are superior as compared to one-side artificially roughened solar air heaters qualitatively and quantitatively both.
Źródło:
Archives of Thermodynamics; 2023, 44, 1; 63--87
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transient velocity and steady state entropy generation in a microfluidic Couette flow containing charged nano particles
Autorzy:
Gorla, R. S. R.
Gireesha, B. J.
Powiązania:
https://bibliotekanauki.pl/articles/264851.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
transient velocity
steady state entropy generation
microfluidic Couette flow
charged nanoparticles
Bejan number and Brinkman number
przepływ Couette'a
liczba Brinkmana
nanocząsteczki
Opis:
An analysis has been provided to determine the transient velocity and steady state entropy generation in a microfluidic Couette flow influenced by electro-kinetic effect of charged nanoparticles. The equation for calculating the Couette flow velocity profile is derived for transient flow. The solutions for momentum and energy equations are used to get the exact solution for the dimensionless velocity ratio and dimensionless entropy generation number. The effects of the dimensionless entropy generation number, Bejan number, irreversibility ratio, entropy generation due to fluid friction and due to heat transfer on dimensionless time, relative channel height, Brinkman number, dimensionless temperature ratio, nanoparticle volume fraction are analyzed.
Źródło:
International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 787-804
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review of Methods and Algorithms for Modelling Transportation Networks Based on Graph Theory
Przegląd metod i algorytmów modelowania sieci transportowych opartych na teorii grafów
Autorzy:
Guze, S.
Powiązania:
https://bibliotekanauki.pl/articles/341823.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Morski w Gdyni. Wydawnictwo Uniwersytetu Morskiego w Gdyni
Tematy:
knapsack problem
domination number
bondage-connected number
MST
maximal flow
transportation network
vulnerability
problem plecakowy
liczba dominowania
liczba zniewolenia spójnego
maksymalny przepływ
sieć transportowa
wrażliwość sieci
Opis:
One of the best ways of modelling a transport network is to use a graph with vertices and edges. They represent nodes and arcs of such network respectively. Graph theory gives dozens of parameters or characteristics, including a connectivity, spanning trees or the different types of domination number and problems related to it. The main aim of the paper is to show graph theory methods and algorithms helpful in modelling and optimization of a transportation network. Firstly, the descriptions of basic notations in graph theory are introduced. Next, the concepts of domination, bondage number, edge-subdivision and their implementations to the transportation network description and modeling are proposed. Moreover, the algorithms for finding spanning tree or maximal flow in networks are presented. Finally, the possible usage of distinguishing concepts to exemplary transportation network is shown. The conclusions and future directions of work are presented at the end of the paper.
Jednym z najlepszych sposobów modelowania sieci transportowej jest użycie grafu z wierzchołkami i krawędziami. Reprezentują one odpowiednio węzły i łuki takiej sieci. Teoria grafów daje możliwość użycia dziesiątek parametrów lub charakterystyk, w tym spójności, drzew spinających lub różnych typów liczb dominowania i związanych z tym problemów. Głównym celem artykułu jest przedstawienie metod i algorytmów teorii grafów pomocnych w modelowaniu i optymalizacji sieci transportowej. Po pierwsze, wprowadzono opisy podstawowych pojęć w teorii grafów. Następnie zaprezentowano koncepcje dominowania, liczby zniewolenia czy podziału krawędzi grafu oraz ich implementacji do opisu i modelowania sieci transportowej. Ponadto przedstawiono algorytmy do wyszukiwania drzewa opinającego i maksymalnego przepływu w sieciach. Wreszcie pokazano możliwe sposoby wykorzystania wyróżnionych koncepcji do przykładu sieci transportowej. Na zakończenia przedstawiono wnioski i przyszłe kierunki prac.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Gdyni; 2018, 107; 25-39
1644-1818
2451-2486
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Gdyni
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sprawdzenie możliwości pomiaru kryzą mimośrodową strumienia medium dla małych liczb Reynoldsa
Analysis of the Possibilities of Measurement with Eccentric Orifice of Flow Medium for Small Reynolds Numbers
Autorzy:
Kasprzak, D.
Mrowiec, A.
Powiązania:
https://bibliotekanauki.pl/articles/275070.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:
kryza mimośrodowa
liczba Reynoldsa
współczynnik przepływu
przetwornik różnicy ciśnienia
eccentric orifice
Reynolds number
flow factor
differential pressure sensor
Opis:
Węgiel to podstawowy surowiec energetyczny w Polsce. Od połowy ubiegłego wieku podejmowano próby spalania koloidalnych zawiesin pyłu węglowego w oleju napędowym lub opałowym. Ze względów ekonomicznych podjęto badania nad wykorzystaniem koloidalnych zawiesin wodno-węglowych CWL (Coal-Water Liquid), jako paliwa w energetyce ciepłowniczej. Pozwala to na obniżenie zawartości NOx i SOx bez konieczności inwestowania w drogie układy odsiarczania i odpylania, co jest atutem ekologicznym i ekonomicznym. Wymagane, ze względów technologicznych, układy pomiaru strumienia dostarczanego paliwa, powinny być tanie w eksploatacji, niezawodne oraz odporne na zanieczyszczenia. Warunki te mogą spełnić kryzy mimośrodowe lub segmentowe. W artykule przedstawiono stanowisko doświadczalno-pomiarowe, pozwalające na przeprowadzenie przepływowych badań wstępnych, kryz mimośrodowych z punktowym odbiorem ciśnienia różnicowego, przy małych liczbach Reynoldsa. Wyniki wykonanych pomiarów charakterystyk przepływowych oraz symulacji numerycznych przedstawiono w tabelach i na wykresach. Dla wybranej kryzy mimośrodowej wyznaczono wartość współczynnika przepływu C w funkcji liczby Reynoldsa. Przedstawione w artykule analizy dotyczą przepływu wody. Planowane są dalsze badania dla oleju hydraulicznego.
The energy industry in Poland is mostly based on coal as an energy resource. Until the half of the previous century studies and attempts were made at burning coal dust-based suspensoids in gas oil and furnace oil, with positive results. For economic reasons, studies and attempts were made at using coal and water-based CWL (Coal-Water Liquid) suspensoids as fuel in the heating industry. Using this fuel leads to a reduction in NOx and SOx percentage without the need for an expensive desulphurization and dust extraction installation, which is a huge economic and ecological advantage. For technological reasons required are systems for measuring the flow of the injected fuel that are cheap in use, reliable and residue-resistant. These requirements can be met by segmental and eccentric orifices. In the article, presented was a research and measurement station which enables its users to conduct introductory flow measurements for eccentric orifices with point reception of differential pressure for small Reynolds numbers. The results of the flow characteristic measurements as well as of numerical simulations were presented in the form of tables and charts. For the selected eccentric orifice the C flow parameter in the Reynolds number function was determined. The analysis of the study results presented in the article refers to the flow of water. The next planned stage of the research will involve flow studies and measurements with the use of hydraulic oil as the medium.
Źródło:
Pomiary Automatyka Robotyka; 2016, 20, 2; 25-28
1427-9126
Pojawia się w:
Pomiary Automatyka Robotyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 44

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