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1

Simulation of incompressible flow past a bluff cylinder by means of a discrete vortex method

Frączak J. W., Burka E. S.

Transactions of the Institute of Fluid-Flow Machinery

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2004

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nr 115

69-81

EN

A two-dimensional viscous, incompressible, unsteady flow past a bluff cylinder with sharp edges is simulated using a purely deterministic Lagrangian model incorporating viscous effects (diffusion and no-slip boundary condition). The method applied is based on a combination of the discrete vortex and the panel method. The viscous diffusion effect is simulated by means of the diffusion velocity method. The evolution of vortical flow past a square cylinder after its impulsive start and motion with constant velocity in resting liquid is simulated for moderate Reynolds numbers and several different angles of incidence.

2

Pomiar natężenia przepływu pulsacyjnego

Burka E., S.

Zeszyty Naukowe Politechniki Białostockiej. Budowa i Eksploatacja Maszyn

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2002

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Z. 9

29--44

PL

Praca stanowi wycinek opracowania zagadnienia przepływomierzy laminarnych do pomiaru natężenia przepływu pulsacyjnego. W pracy rozwiązano analitycznie zagadnienie rozkładu prędkości płynu nieściśliwego w zamkniętych kanałach prostoosiowych o przekroju trójkątnym oraz wyznaczono zależność funkcyjną zachodzącą pomiędzy spadkiem hydraulicznym a prędkością średnią w przekroju poprzecznym. Następnie podjęto zadanie doświadczalnego sprawdzenia zależności funkcyjnej , wyprowadzonej postaci równania i przedstawiono wyniki przeprowadzonych badań oraz zaprezentowano przepływomierz prototypowy.

EN

This paper is a fragment of a work devoted to the problem of laminar flowmeters for measuring pulsation flow output. In the first part of the paper the author uses the variation method to reduce the problem, of a fixed laminar flow through a rectiaxial duct with a triangular cross-section to an ordinary differential equation with boundary condition. This permits the determination of velocity distribution in the cross section and of the functional relation between the hydraulic drop and the mean velocity (11) in a duct whose cross-section is an equilateral triangle. The second part of the paper contains the experimental results proving the validity of the theoretical deductions.

3

Cavitation in hydraulic machinery

Burka E. S.

Transactions of the Institute of Fluid-Flow Machinery

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2002

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nr 110

7-19

EN

The phenomenon of cavitation can be revealed, among others, in technics by decreased efficiency of machinery and installations, in medicine by negative action on heart and circulatory system, in biology by disintegration of erythrocytes and bacteria. Cavitation penetrates each year deeper and deeper to many regions of technics, chemistry, biology and medicine. Cavotation as the process of formation of fluid discontinuity under negative pressures is a very complex phenomenon and depends on fluid parameters and its motion. For the time being no consistent theory of the cavitation phenomenon was produced that would include all fluid properties. Several simple cases were only analyzed. The results of that analysis give a flavour of cavitation phenomenon, sufficient enough to make preliminary considerations of the influence of basic factors (pressure, temperature, velocity) on the course of that phenomenon. The change of the motion character, caused by cavitation, results in the change in pressure distribution of the whole flow area and in such away affects the phenomenon itself. In this paper individual phases of that phenomenon are examined: a) initial phase of cavitation formation; b) phase of developing cavitation, and c) phase of fully developed cavitation.

4

Zagadnienia fizyki kawitacji

Burka E. S.

Zeszyty Naukowe Politechniki Białostockiej. Budowa i Eksploatacja Maszyn

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2001

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Z. 8

43-50

PL

Praca ma na celu zwrócenie uwagi na bardzo aktualny dziś problem hydrodynamiki, jakim jest zjawisko kawitacji, niosące za sobą m.in.: w technice - obniżenie sprawności maszyn i urządzeń oraz erozję kawitacyjną, w medycynie - ujemne oddziaływanie na mięsień sercowy i układ krążenia, w biologii - rozkład czerwonych ciałek krwi i bakterii. Rozpatrzono poszczególne fazy tego zjawiska: początkową - tworzenia się kawitacji, fazę rozwoju i fazę kawitacji w pełni rozwiniętej.

EN

The phenomenon of cavitation is followed, among others, in technics by decreased efficiency of machinery and installations, in medicine by negative action on heart and circulatory system, in biology by disintegration of erythrocytes and bacteria. Cavitation penetrates each year deeper and deeper to many regions of technics, chemistry, biology and medicine. Cavitation as the process of formation of fluid discontinuity under negative pressures is a very complex phenomenon and depends on fluid parameters and its motion. For the time being no consistent theory of the cavitation phenomenon was produced that would include all fluid properties. Several simple cases were only analyzed. The results of that analysis give a view of cavitation phenomenon, sufficient enough to make preliminary considerations on the influence of basic factors (pressure, temperature, velocity) on the course of that phenomenon. The change itself of the motion character caused by cavitation results in the change in pressure distribution of the whole flow area and by that influence the phenomenon itself. In this paper individual phases of that phenomenon are examined: a) initial phase of cavitation formation; b) phase of developing cavitation, and c) phase of full cavitation.

5

In memory of Professor Robert Szewalski

Burka E. S.

Turbulence : international journal

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2000

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Vol. 6-7

7-25