Wyniki wyszukiwania - BazTech

1

Numerical Simulation of the Condensing Effect of Different Suction Slots on Fiber Strands in a Compact Siro Spinning Machine with Lattice Apron

Han Chenchen, Gao Weidong, Chen Lifen

Autex Research Journal

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2020

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Vol. 20, no. 1

1--10

EN

Compact-siro spun with lattice apron combines compact spinning and siro spinning, and is widely put into practice. In this paper, compact-siro spun models with the parallel shaped slots, oblique parallel shaped slots and V-shaped slots were simulated. Based on the airflow data in the condensing zone, the geometrical model of single fiber is built, and then the trajectory of single fiber can be got. The morphological changes and movement process of fiber strands in the flow field of condensing zone were verified by the comparison experiments of yarn morphology, hairiness, tensile and evenness properties. The results showed that the V-shaped slot achieved the optimal agglomeration effect and yarn performance. The theory analysis gives foundation and explanation for the experiment, and also provides a theoretical basis for optimizing the properties of compact-siro yarn in production practice.

2

Effect of two distinct patches of Myriophyllum species on downstream turbulence in a natural river

Przyborowski Łukasz, Łoboda Anna Maria, Bialik Robert Józef

Acta Geophysica

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2019

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Vol. 67, no. 3

987--997

EN

Velocity profiles upstream and downstream of two aquatic plant species that are similar in morphology but differ in patch structures were measured in a natural river. Turbulence statistics were analyzed after thorough data filtering. In the wake of the M. alterniflorum, which was a slender, 0.3 m wide and 1.2 m long patch of aspect ratio 1:4, there were distinctive peaks in both, turbulence intensity and turbulent kinetic energy, which indicated increased lateral mixing. In contrast to the M. alterniflorum, turbulence statistics in the wake of the M. spicatum, which was the larger, 2 m wide and 2.4 m long patch of aspect ratio 1:1.5, indicated increased lateral shear of a greater magnitude. The turbulent kinetic energy was diminished in the closest layer to the bed downstream the both plants, although, in the case of M. alterniflorum, the observed values were similar to those upstream. The occurrence of the mixing layer below the height of M. spicatum was visible in the power spectral density plot. In both cases, ejections in the wake diminished in favor of other coherent structures. The shape and configuration of a patch are decisive factors governing the occurrence of flow instabilities downstream of the patch.

3

Three-dimensional computational fluid dynamics modelling of a proton exchange membrane fuel cell with a serpentine micro-channel design

Zinko T., Jaworski Z., Pianko-Oprych P.

Chemical and Process Engineering

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2018

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Vol. 39, nr 2

143-–154

EN

The aim of this paper was to demonstrate the feasibility of using a Computational Fluid Dynamics tool for the design of a novel Proton Exchange Membrane Fuel Cell and to investigate the performance of serpentine micro-channel flow fields. A three-dimensional steady state model consisting of momentum, heat, species and charge conservation equations in combination with electrochemical equations has been developed. The design of the PEMFC involved electrolyte membrane, anode and cathode catalyst layers, anode and cathode gas diffusion layers, two collectors and serpentine micro-channels of air and fuel. The distributions of mass fraction, temperature, pressure drop and gas flows through the PEMFC were studied. The current density was predicted in a wide scope of voltage. The current density – voltage curve and power characteristic of the analysed PEMFC design were obtained. A validation study showed that the developed model was able to assess the PEMFC performance.

4

Three dimensional flow and mass transfer analysis of a second grade fluid in a porous channel with a lower stretching wall

Khan N. A., Naz F.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 2

359--376

EN

This investigation analyses a three dimensional flow and mass transfer of a second grade fluid over a porous stretching wall in the presence of suction or injection. The equations governing the flow are attained in terms of partial differential equations. A similarity transformation has been utilized for the transformation of partial differential equations into the ordinary differential equations. The solutions of the nonlinear systems are given by the homotopy analysis method (HAM). A comparative study with the previous results of a viscous fluid has been made. The convergence of the series solution has also been considered explicitly. The influence of admissible parameters on the flows is delineated through graphs and appropriate results are presented. In addition, it is found that instantaneous suction and injection reduce viscous drag on the stretching sheet. It is also shown that suction or injection of a fluid through the surface is an example of mass transfer and it can change the flow field.

5

Effect of the numerical grid density on the modelling of fluid flow in a stirred tank with a PMT impeller

Story A., Jaworski Z.

Czasopismo Techniczne. Chemia

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2014

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R. 111, z. 2-Ch

115--123

EN

The paper present the results of numerical simulations performed for a stirred tank equipped with a PMT type impeller, filled up with a Newtonian fluid. The effects of the grid density and mesh quality and also of the simulation mode on the modelling of fluid flow in a stirred tank were studied. The results are compared with literature data obtained from LDA measurements. It was found that denser numerical grids give more detailed information about generated flow field near the impeller blades. Additionally, better compatibility of predicting and experimental results was obtained in the case of the transient mode simulation, what also demonstrates a significant effect of the angular position of the impeller against baffles on the generated velocity field.

PL

W artykule przedstawiono wyniki symulacji numerycznych prowadzonych dla mieszalnika z mieszadłem typu PMT, wypełnionego cieczą newtonowską. Zbadano wpływ gęstości i jakości siatki numerycznej oraz trybu prowadzenia symulacji numerycznych na modelowanie pola prędkości cieczy w mieszalniku. Wyniki porównano z literaturowymi danymi eksperymentalnymi z pomiarów LDA. Stwierdzono, że gęstsza siatka numeryczna daje bardziej szczegółowe informacje o generowanym polu prędkości w pobliżu łopatek mieszadła. Dodatkowo lepszą zgodność wyników przewidywanych z doświadczalnymi otrzymano w przypadku prowadzenia symulacji w trybie nieustalonym, co świadczy o dużym wpływie kątowego położenia mieszadła względem przegród na generowane pole prędkości.

6

Numeryczne modelowanie dwuwymiarowego pola przepływu na obszarach zalewowych

Siuta T.

Czasopismo Techniczne. Środowisko

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2011

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R. 108, z. 2-Ś

219-225

PL

W artykule przedstawiono i poddano analizie przykładowe wyniki symulacji numerycznej dwuwymiarowego pola ustalonego przepływu na terenach zalewowych podgórskiej rzeki Raby tuż poniżej zbiornika retencyjnego w Dobczycach. Obliczenia mają charakter poglądowy i mają na celu przedstawienie tych wyników z rozwiązania dwuwymiarowego, których nie można otrzymać za pomocą konwencjonalnych modeli jednowymiarowych, powszechnie stosowanych przy wyznaczaniu stref zalewu. Wyniki obliczeń wykorzystano do wyznaczania potencjalnych stref zalewu, będącego skutkiem przerwania lub przelania się wody przez koronę wału.

EN

In the paper the results of numerical simulation of steady 2D flow field at floodplains of Raba river just downstream of Dobczyce reservoir were presented. The purpose of this calculation is presentation of qualitative hydraulics effects which are unattainable by conventional 1D models widely applied in the field of floodplains determination. This hydraulics effects concern the potential flow due to levee breach or levee overtopping mainly.

7

Modelowanie numeryczne pola przepływu wokół budynków

Folusiak M.

Prace Instytutu Lotnictwa

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2008

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Nr 3-4 (194-195)

171-175

PL

W artykule przedstawiono wyniki dwu- i trójwymiarowych symulacji numerycznych opływu budynków wykonanvch z wykorzystaniem pakietu obliczeniowego ANSYS Fluent. Rozpatrzono cztery przypadki obliczeniowe budynków o różnej szerokości.

EN

In this paprer, results of two- and three-dimensional numerical investigations on the flow field near buildings, which were performed using ANSYS Fluent, are presented. For numerical cases of buildings of different width were investigated.

8

Application of a Stereo PIV system for investigations of flow fields in towing tank and cavitation tunnel

Anschau P., Mach K. P.

Archives of Civil and Mechanical Engineering

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2007

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Vol. 7, no 3

5-17

EN

A newly installed submersible stereo PIV system, designed for the use in the towing tank and operating perpendicular to the main flow direction, is described. This Stereo ParticIe Image Velocimetry system allows the contactfree, 3-dimensional determination of velocity fields in the towing tank and cavitation tunneI. Flow conditions can be analyzed with a resolution of a few thousand points simultaneously, with a frame rate of up to 15 pictures per second, providing a good insight into flow characteristics without disturbing the flow. The paper will describe two applications of the system that have already been carried out (propeller in open water condition and in the cavitation tunnel) and will discuss merits and disadvantages of the new system. The potentials for validation of CFD calculations will be shortly discussed. Future plans for further applications of the system will be introduced.

PL

Opisany został niedawno uruchomiony podwodny system stereowizyjny PIV (ParticIe Image Velocimetry), przeznaczony do pomiarów w basenie holowniczym i pracujący prostopadle do głównego kierunku przepływu. System pozwala na bezkontaktowy pomiar trójwymiarowego pola prędkości w basenie holowniczym i w tunelu kawitacyjnym. Przepływ może być analizowany z rozdzielczością kilku tysięcy punktów jednocześnie, z częstotliwością do 15 klatek na sekundę, co daje dobry wgląd w pole prędkości bez zakłócania przepływu. Referat opisuje dwa przypadki zastosowania (pędnik odosobniony w basenie holowniczym i w tunelu kawitacyjnym), oraz zalety i wady nowego systemu. Krótko omówione zostały możliwości weryfikacji obliczeń CFD. Przedstawiono plany zastosowania systemu w przyszłości.

9

Deviation and profile losses in a turbine cascade at off-design incidences

Willinger R., Haselbacher H.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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1999

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nr 115

431--443

EN

This paper presents details of an investigation of the two-dimensional flow field in a linear turbine cascade at off-design incidences. The cascade geometry corresponds to the tip section of a moving blade row of a gas turbine of recent design. Six different inlet flow angles, ranging from high positive incidence to high negative incidence, have been investigated experimentally. A three hole pressure probe was traversed immediately downstream of the trailing edge plane. Further work concerned the computation of the cascade flow field with a finite-element based Navier-Stokes solver. The k/ɛ-model was used to account for the turbulent behavior of the flow. The measurement and computational results are compared with an established profile incidence loss correlation.