Wyniki wyszukiwania - BazTech

1

Static analysis of thin-walled beams using two-phase local-nonlocal integral model

Günay M. G.

Archives of Mechanics

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2023

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Vol. 75, nr 6

673--695

EN

A mathematical model is developed for static analysis of small-scale thinwalled beams having arbitrary cross sections. Constitutive relations of the thin-walled beams are defined upon the two-phase local-nonlocal mixture model with integral formulation. The developed model includes flexural-torsional coupling and warping effects. Governing equations of the thin-walled beams having nonlocal property are derived by using the principle of minimum potential energy. The displacement based finite element method is used to solve both local and nonlocal part of the model. The effect of the nonlocal parameters on the static behavior of micro-scale thin-walled beams having closed and open cross-sections is examined and discussed for various nonlocal parameters and boundary conditions.

2

Novel model for emptying of a self-pressurised nitrous oxide tank

Szymborski Jakub, Kardaś Dariusz

Archives of Thermodynamics

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2022

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Vol. 43, no 3

141--173

EN

Nitrous oxide is often used in the space industry, as an oxidiser or monopropellant, mostly in self-pressurised configurations. It has potential for growth in use due to the recent rising interest in green propellants. At the same time, modelling the behaviour of a self-pressurising nitrous oxide tank is a challenging task, and few accurate numerical models are currently available. Two-phase flow, heat transfer and rapid changes of mass and temperature in the investigated system all increase the difficulty of accurately predicting this process. To get a get better understanding of the emptying of a self-pressurised nitrous oxide tank, two models were developed: a phase equilibrium model (single node equilibrium), treating the control volume as a single node in equilibrium state, and a phase interface model, featuring a moving interface between parts of the investigated medium. The single node equilibrium model is a variation of equilibrium model previously described in the literature, while the phase interface model involves a novel approach. The results show that the models are able to capture general trends in the main parameters, such as pressure or temperature. The phase interface model predicts nitrous oxide as a liquid, a two-phase mixture, and vapour in the lower part of the tank, which is reflected in the dynamics of changes in pressure and mass flow rate. The models developed for self-pressurisation, while created for predicting nitrous oxide behaviour, could be adapted for other media in conditions near vapour– liquid equilibrium by adding appropriate state equations.

3

Dwupasmowy silnik reluktancyjny przełączalny przeznaczony do napędu robota kuchennego

Bogusz P., Korkosz M., Prokop J.

Maszyny Elektryczne : zeszyty problemowe

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2015

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Nr 1 (105)

21--26

PL

W robotach kuchennych zazwyczaj są stosowane silniki komutatorowe. Alternatywą dla nich są silniki z komutacją elektroniczną. Jedną z takich maszyn jest silnik reluktancyjny przełączalny. Autorzy proponują zastosowanie dwupasmowej konstrukcji silnika reluktancyjnego przełączalnego 4/2 do napędu robota kuchennego. Konstrukcja została opracowana z uwzględnieniem ograniczeń technologicznych napędu robota kuchennego. W pracy wyznaczono charakterystyki statyczne na bazie modelu polowego badanego silnika. Zostały wyznaczone przebiegi czasowe prądów i momentu elektromagnetycznego dla wybranych punktów pracy silnika. Zamieszczono wnioski dotyczące analizowanej konstrukcji.

EN

The commutator motos are usually used in food processors. Motors with electronic commutation can be a substitute for them, for example Switched Reluctance Machine (SRM). The authors propose the use of two-phase Switched Reluctance Machine 4/2 to drive a food processor. The motor construction was developed taking into account the technological limitations of a food processor drive. In the paper, the static characteristics based on the field model of tested motor were determined. The current waveforms and electromagnetic torque for the selected motor working points were determined. Conclusions concerning the analyzed construction were placed.

4

Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

Elazhary A., Soliman H.

Archives of Thermodynamics

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2012

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Vol. 33, no. 2

47-6

EN

An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 [ less than or equal to] JG [ less than or equal to] 10 m/s and 0.02 [ less than or equal to] JL [ less than or equal to] 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

5

Udział objętościowy gazu w dwufazowym przepływie opadającym gaz-ciecz w minikanałach równoległych

Miłaszewicz B.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2010

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vol. 339, z. 8

55--71

PL

W pracy zaprezentowano krótki przegląd metod wyznaczania udziałów objętościowych gazu w przypadku wystąpienia przepływu pęcherzykowego i korkowego. Przedstawiono wyniki pomiaru udziałów objętościowych gazu na podstawie badań własnych. Porównano otrzymane dane eksperymentalne z obliczonymi według wybranych modeli.

EN

The article presents short review of void fraction determination methods for bubble and slug flow. The results of research of void fraction in parallel minichannels have been presented. Measured void fractions were compared with calculated from existing models.

6

Badanie hydrodynamiki przepływu dwufazowego gaz-ciecz w minikanałach

Wengel M.

Zeszyty Naukowe. Inżynieria Środowiska / Politechnika Opolska

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2010

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vol. 339, z. 8

73--86

PL

W artykule przedstawiono próbę opisu zjawisk hydrodynamicznych zachodzących podczas przepływu dwufazowego gaz-ciecz w minikanałach w oparciu o badania eksperymentalne. Metodę wizualizacji przepływu oraz fluktuacje zmian poziomów szarości zarejestrowanych obrazów powiązano ze strukturami przepływu i dokonano oceny hydrodynamiki przepływu w zależności od średnicy hydraulicznej. Przeprowadzona analiza pozwoliła wykazać znaczące różnice w poszczególnych minikanałach.

EN

The article presents an attempt to describe the hydrodynamic phenomena occurring during the two-phase flow in gas-liquid minichannels based on experimental studies. The method of flow visualization and the fluctuation of gray level changes recorded images were related with the flow structures and made evaluation of the hydrodynamics of flow according to the hydraulic diameter.