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  1. 11 Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
  2. 6 Archives of Thermodynamics
  3. 6 Inżynieria Chemiczna i Procesowa
  4. 4 International Journal of Applied Mechanics and Engineering
  5. 2 Acta of Bioengineering and Biomechanics
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  1. 3 2022
  2. 5 2021
  3. 4 2020
  4. 2 2019
  5. 1 2018
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  1. 3 Fadodun O. G.
  2. 3 Jeżowiecka-Kabsch K.
  3. 3 Strzelecka K.
  4. 3 Tuliszka-Sznitko E.
  5. 2 Al-Dulaimi M. A.
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1
Content available remote Heat transfer in a turbulent channel flow with a permeable wall
100%
Kuznetsov A. V. , Xiang P.
International Journal of Applied Mechanics and Engineering
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2006
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tom Vol. 11, no 3
705-713
EN
A problem of turbulent flow in a channel with a permeable wall recently considered in Hahn and Choi (2002) is extended to include heat transfer. A model is utilized to investigate this problem numerically. The modeling is based on the assumption that the flow in the channel is turbulent while in the porous block the flow remains laminar. The wall functions approach is utilized to determine the boundary conditions for the k and equations. The dependence of the Nusselt number on the Darcy and Reynolds numbers is investigated.
2
CAD/CFD Interaction in Sub Sea Vehicle Design
80%
Fuglestad A. L. , Grahl-Madsen M.
|
2004
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tom Vol. 9, No. sp. I
5--15
EN
The present paper report on the use of an interface tool between software for CAD (Computer Assisted Design) and CFD (Computational Fluid Dynamics). Experimental obtained data for the drag force acting on a model prototype of the HUGIN 3000 and data obtained from a Computer Aided Analysis of the drag force carried out by CFD, is also presented. The HUGIN 3000 was developed in the nineties, by Kongsberg Maritime and FFl (Norwegian Defence Research Establishment). The experimental results in this paper, origins from a model test carried out by Marintek. The range of Reynolds numbers for both the experimental data and the computational results is 2.707x107 to 1.146x10 sup>6. The agreement between the experimental data and the computed results is good. Panicularly for the highest Reynolds numbers, the prediction of drag force by CFD seems to be remarkable good.
3
Content available remote The Lattice Boltzmann method for fluid mixing: a comparison with the finite element method
80%
Egidi N. , Misici L. , Piergallini R. , Tosi F.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2004
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tom Vol. 8, No 1
5-15
EN
In this article we study three-dimensional mixing of an incompressible viscous fluid subjected to the force of rotating blades in a vessel, with a low Reynolds number. The results obtained with the lattice Boltzmann method are compared with the ones previously obtained using the finite element method. All the qualitative and quantitative parameters of the two simulations agree.
4
Content available Numerical investigation for convective heat transfer of nanofluid laminar flow inside a circular pipe by applying various models
70%
Saeed F. R. , Al-Dulaimi M. A.
Archives of Thermodynamics
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2021
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tom Vol. 42, no 1
71--95
EN
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.
5
Content available Development of a source code to analyze the effect of Reynolds number on a square lid driven cavity
60%
Rahi K. H. , Mortuza G. M. , Al-Faruk A.
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tom Vol. 2, No 2
147--154
EN
Numerical simulations of two-dimensional, steady, incompressible lid driven flow in a square cavity were investigated in this work. A commercial finite volume package of ANSYS-FLUENT was used to analyze and visualize the nature of the flow inside the cavity at different Reynolds Numbers. In addition, a MATLAB code was developed and validated by comparing the results with the reference values from literature. Staggered grid was employed in the discretization of the cavity to avoid checkerboard pressure while developing the code. The governing equations were discretized in terms of velocity and pressure fields. The artificial compressibility method was used to de-couple the pressure and velocity terms in the governing equations. A 129×129 grid system was used in both cases. The effects of Reynolds number (100≤ Re ≤ 1000) on the flow characteristics were illustrated through an analysis of stream function, velocity vector, pressure co-efficient and velocity contours. The thinning of the wall boundary layers with an increase in the Reynolds number is evident from the u and v velocity profiles along the vertical and horizontal lines at the geometric center, although the rate of this thinning is very slow for Re> 5000.
6
Content available Pomiar kryzą segmentową strumienia medium dla małych liczb Reynoldsa
60%
Mrowiec A. , Kasprzak D.
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
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2016
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tom Nr 49
75--78
PL
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.
EN
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.
7
The influence of early stages of development of wind waves on the effective roughness of the water free surface
60%
Druet C. , Siwecki R.
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tom 18
8
Content available remote Experimental assessment of the drag coefficient during butterfly swimming in hydraulic flume
60%
Taiar R. , Bertucci W. , Letellier T. , Benkemis I. , Toshev Y.
Acta of Bioengineering and Biomechanics
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2005
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tom Vol. 7, nr 2
98-108
EN
A body when moving in a fluid is to withstand drag that is proportional to the drag coefficient, the frontal surface area, and the square of the body velocity relative to the fluid velocity (VOGEL [14]). The aim of our study was to determine the relationships between the drag coefficient (CD) and the Reynolds number (Re) for a high-level swimmer. In TAIAR et al. [12], three most propulsive butterfly positions have been defined: the end of the external sweep (beginning of the cycle), the end of the internal sweep (middle of the cycle), and the end of the thrust (end of the cycle). These three positions were reproduced using real-size mannequins articulated ui real-velocity conditions. Experiments have been done ui the large-scale hydraulic flume of the University' of Nantes. Two types of the curves CD (Re) were obtained: for the "best swimmer" and for ''other swimmers". Following the swimming of the ex-word champion Pankratov during the World Championship m Rome (1994) the mannequin representing the "best swimmer" has been positioned similarly to the ex-world champion at the beginning, in the middle and at the end of cycle. The body positions of Pankratov have been obtained using the image analysis software Schleihaui 4.0. In order to obtain the curves CD (Re) representing "other swimmers", the body positions of lower-level swimmers have been used at the beginning, in the middle and at the end of swimming cycle. The two types of curves show well the gap between the techniques of the "best swimmer" and "other swimmers". Our study shows the importance of the body position dining the swimming cycle to minimizing the drug and to assuring better propulsion, i.e. better performance. The results show that the most effective swimmers optimise the body positions in order to reduce the frontal surface and therefore to minimize the drag.
9
Anomalne zjawisko przepływowe wywołane dodatkami polimerowo-micelarnymi
60%
Matras Z. , Walczak S.
Inżynieria Chemiczna i Procesowa
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2006
|
tom T. 27, z. 3/1
965-974
PL
Przedstawiono zjawisko redukcji oporów przepływu przez jednoczesne dodanie do rozpuszczalnika wielkocząsteczkowego polimeru i substancji powierzchniowo czynnej. W takim przypadku strefa przejścia między ruchem laminarnym i turbulentnym jest znacznie rozszerzona i przesuwa się w kierunku większych liczb Reynoldsa w porównaniu z przypadkami dodania do rozpuszczalnika jedynie polimeru lub wyłącznie substancji powierzchniowo czynnej. Przedstawiono i przeanalizowano wstępne wyniki badań doświadczalnych.
EN
The phenomena of drag reduction by means of surfactant and high molecular polymer added simultaneously to the solvent are presented and discussed. It appears that transition zone between laminar and turbulent flow extends towards larger Reynolds numbers in comparison with those occurring in the case of high molecular polymer or surfactant added separately. Initial experimental results are presented and examined.
10
Wpływ liczby Reynoldsa na strukturę pola prędkości za rozszerzeniem rury
60%
Jeżowiecka-Kabsch K. , Strzelecka K.
Inżynieria Chemiczna i Procesowa
|
2006
|
tom T. 27, z. 3/1
875-887
PL
Metodą anemometrii laserowej (LDA) wykonano pomiary prędkości miejscowych (uśrednionych i fluktuacyjnych) za nagłym osiowosymetrycznym rozszerzeniem rury. Zbadano przepływy o liczbach Reynoldsa Red (1000; 100 000) przez rury z dwoma znacznie różniącymi się stopniami rozszerzenia d/D = (0,53; 0,82). Na podstawie otrzymanych wyników wyznaczono pola prędkości uśrednionych, granice rozdziału strugi tranzytowej i stref recyrkulacji oraz pola względnych fluktuacji prędkości w obszarze za rozszerzeniem rury dla różnych liczb Reynoldsa.
EN
Local velocity measurements (mean and fluctuational) behind pipe axisymmetric sudden expansion have been obtained with laser-Doppler anemometer techniques. Flows with Reynolds numbers (Red) from 1000 to 100 000, for two different values of diameter ratio d/D = (0,53; 0,82) were investigated. Mean velocity distribution, jet boundary, recirculation zones and relative velocity fluctuations behind pipe sudden expansion are presented for various Reynolds numbers.
11
Content available remote Modelowanie turbulencji w obszarze uderzenia kołowej strugi
60%
Bartoszewicz J. , Bogusławski L.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2000
|
tom nr 117, vol. 2
21-26
PL
W pracy przedstawiono wyniki analizy numerycznej oraz własnych badań eksperymentalnych, dotyczących kształtowania się turbulencji w obszarze uderzenia oraz początkowego odcinka spływu wzdłuż ściany w osiowosymetrycznej strudze uderzającej. Rozwiązywany numerycznie układ równań transportu uzupełniony został o model turbulencji k-ε dla dużych liczb Reynoldsa oraz logarytmiczne prawo ściany. Badania wykonano przy użyciu stałotemperaturowych sond drutowych oraz rurką Pitota. Wyznaczono rozkłady wartości średnich prędkości i ciśnienia oraz parametrów turbulencji w obszarze uderzenia.
EN
In the paper are presented results of numerical analysis and experimental investigations of turbulence variations in impinging region and along wall in axisymmetric impinging jet. Numerical system of transport equations was complete by high-Reynolds turbulence model and logarithmic low of wall. Constant temperature anemometer with "hot-wire" probe and Pitot probe was used. Calculated distribution of average value and turbulence of parameters in impinging region are presented.
12
Content available remote Zależności opisujące zmianę turbulentnej liczby Prandtla w przepływie realizowanym w rurze
60%
Rup K. , Soczówka M.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2000
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tom nr 117, vol. 2
169-174
PL
Praca prezentuje rezultaty obliczeń numerycznych wykonanych dla przepływu przez rurę kołową wody i powietrza z wymianą ciepła. W obliczeniach uwzględniono trzy warianty zmian turbulentnej liczby Prandtla Pr1, po przekroju poprzecznym rury. Wyniki obliczeń porównano z dostępnymi wynikami badań doświadczalnych w literaturze.
EN
The paper presents results of numerical calculations of turbulent exchange of momentum and heat in the flow of air and water in circular pipe. Solutions included three variants of changes of turbulent Prandtl number across the pipe. The obtained results were compared with corresponding results of experimental works available in literature.
13
Content available Performance analysis of three sides solar air heater having roughness elements as a combination of multiple-v and transverse wire on the absorber plate
60%
Kumar D. , Prasad L.
Archives of Thermodynamics
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2020
|
tom Vol. 41, no 3
125--146
EN
Artificial roughness has been found to enhance the thermal performance from the collector to air in the solar air heater duct. This paper presents the results of experimental investigation on thermal performance of three sides solar air heater roughened with combination of multiple-v and transverse wire. The range of variation of system and operating parameters is investigated within the limits of relative roughness pitch of 10−25, relative roughness height of 0.018 −0.042, angle of attack of 30°−75° at varying flow Reynolds number in the of range of 3000−12000 for fixed value of relative roughness width of 6. The augmentation in fluid temperature flowing under three side’s roughened duct is found to be 36.57% more than that of one side roughened duct. The maximum thermal efficiency is obtained at relative roughness pitch of 10 and relative roughness height of 0.042, and angle of attack of 60°. The augmentation in thermal efficiency of three sides over those of one side roughened duct is found to be 46−57% for varying values of relative roughness pitch, 38−50% for varying values of relative roughness height, and 40−46% for varying values of angle of attack.
14
Analiza porównawcza wybranych modeli ruchu cząstki sferycznej w jednowymiarowym przepływie dwufazowym
60%
Panas A. , Fafiński T.
Modelowanie Inżynierskie
|
2008
|
tom T. 5, nr 36
387-394
PL
W pracy porównano wybrane modele ruchu kropli traktowanej jako nieodkształcalna cząstka sferyczna w polu przepływu gazu. Bezpośrednim celem prezentowanej analizy było określenie różnic pomiędzy rozwiązaniami zagadnienia ruchu kropli uzyskiwanymi przy zastosowaniu różnych przybliżeń dla wyrażenia składowej sił aerodynamicznych w równaniach ruchu. Analizowano wybrane przybliżenia aproksymacyjne dla współczynnika oporu kropli w szerokim zakresie zmienności liczby Reynoldsa oraz rozwiązania analityczne i numeryczne zagadnienia przyspieszania kropli w przepływie jednowymiarowym.
EN
Modelling results of an aerosol droplet motion in gaseous fluid have been discussed. The analysis is focused on differences between the results obtained for different approximations of the aerodynamic force component in the governing equation of motion. The drag force has been modelled applying selected expressions for the drag coefficient in a wide range of instantaneous Reynolds number. The droplet has been considered as a rigid (non – deformable) spherical particle. Results of analytical calculations have been compared with the outcomes of numerical calculations. Numerical analysis has been performed using popular CFD FLUENT and COMSOL packages. Some typical expressions for the particle drag coefficient have been considered. For the simplicity sake the analysis has been limited to a particle response to a one-dimensional flow. The main goal of the whole analysis is to clarify picture of complex heat and mass transfer phenomena in two-phase duct flows in icing conditions. The obtained results will enable verification of a CFD analysis for cases of a more complicated flow geometry.
15
Stanowisko pomiarowe do wyznaczania parametrów przepływu wody w rurociągach
60%
Torbus S. A. , Grzembski M. , Prałat K.
Rynek Energii
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2020
|
tom Nr 6
21--29
PL
W części teoretycznej pracy scharakteryzowano elementy stanowiska pomiarowego wraz z budową i zasadą ich działania. Przedstawiono również algorytm przeprowadzania pomiarów, których wyniki umożliwiają wyznaczenie wartości liczby Reynoldsa, liczby (współczynnika) przepływu i rodzaju przepływu. Praktyczna część pracy polegała na zbudowaniu stanowiska pomiarowego, umożliwiającego wyznaczenie parametrów przepływu wody w rurociągu zgodnie z aktualnie stosowanymi w przemyśle metodami i przyrządami pomiarowymi. Przeprowadzono szereg pomiarów i obliczeń, a następnie dokonano analizy uzyskanych wyników i sformułowano wnioski.
EN
The theoretical part of this paper presented elements of the measuring stand with the construction and principle of their operation. Also presented measurement algorithm, the results of which allow determining the value of Reynolds number, number (coefficient) of flow and type of flow. The aim of the practical part of thesis was to build a measuring position enabling the determination of water parameters in the pipeline in accordance with measurement methods and instruments currently used in industry. A number of measurements and calculations were carried out, and then the results obtained were analyzed and conclusions were formulated.
16
Content available remote Homogeneous / heterogeneous condensation dynamics in turbulent low pressure turbine flows
60%
Winkler G. , Heiler M. , Schnerr G. H.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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1999
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tom nr 115
445--456
EN
This paper is dedicated to gain a better understanding of condensation phenomena in turbulent transonic environment. A 2-D finite volume code has been developed that does also include three different condensation models: pure homogeneous, pure heterogeneous and simultaneous homogeneous/heterogeneous condensation, as well as imperfect gas effects. To be applicable to a variety of technical problems, the code has been extended by a low Reynolds number two equation turbulence model [2 , 14] . The results show excellent agreement with experiments. (Applications: steam turbine L, tip section of steam turbine Bak).
17
Content available Numerical investigation and sensitivity analysis of turbulent heat transfer and pressure drop of Al2O3/H2O nanofluid in straight pipe using response surface methodology
60%
Fadodun O. G. , Amosun A. A. , Salau A. O. , Olaloye D. O. , Ogundeji J. A. , Ibitoye F. I. , Balogun F. A.
Archives of Thermodynamics
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2020
|
tom Vol. 41, no 1
3--30
EN
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.
18
Content available Numerical investigation for convective heat transfer of nanofluid laminar flow inside a circular pipe by applying various models
60%
Saeed F. R. , Al-Dulaimi M. A. , Saeed F. R. , Al-Dulaimi M. A.
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19
Content available Numerical investigation and sensitivity analysis of turbulent heat transfer and pressure drop of Al2O3/H2O nanofluid in straight pipe using response surface methodology
60%
Fadodun O. G. , Amosun A. A. , Salau A. O. , Olaloye D. O. , Ogundeji J. A. , Ibitoye F. I. , Balogun F. A. , Fadodun O. G. , Amosun A. A. , Salau A. O. , Olaloye D. O. , Ogundeji J. A. , Ibitoye F. I. , Balogun F. A.
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nr 1
20
Content available Analysis of selected aspects of a tank gassing-up process on board liquefied petroleum gas carrier. Part I
60%
Wieczorek A. , Wieczorek A.
Archives of Thermodynamics
|
2021
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