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1
Content available remote One-Dimensional Unsteady Flow : a New Presentation of the Issue
100%
Dowkontt S. , Dowkontt G. A.
Machine Dynamics Research
|
2015
|
tom Vol. 39, No. 4
31-41
EN
The subject of the article is a one-dimensional unsteady flow. The authors introduce ζ , a new function which expresses the position of liquid planes in the flow relative to the positions they occupied when the fluid was at rest. This enabled the replacement of two partial differential equations of the first order included in the system of equations describing one-dimensional unsteady flow by a partial differential equation of the second order for function ζ .
2
Analiza wzajemnego oddziaływania w warunkach dynamicznych obciążeń mechanicznych zaworu wylotowego i gniazda „pływającego” silnika lotniczego dużej mocy
100%
Ostapski W. , Dowkontt S.
Logistyka
|
2015
|
tom nr 3
3646--3655, CD 1
PL
W pracy przedstawiono symulacje stanu naprężeń i odkształceń zaworu w trakcie dynamicznego osiadania na gnieździe pływającym głowicy silnika lotniczego tłokowego dużej mocy. Do modelu cyfrowego i symulacji wykorzystano programy ANSYS, ADAMS i LS-DYNA.
EN
The paper presents simulations of stress and deformation of the valve during dynamic subsidence on the “floating” socket in head of high powered piston aircraft engine. Digital model and simulation were made using ANSYS, ADAMS and LS-DYNA software.
3
Symulacja stanu naprężeniowo-odkształceniowego łożyska kulkowego w funkcji wewnętrznych parametrów geometrycznych w warunkach obciążeń próby trwałościowej
100%
Ostapski W. , Dowkontt S.
Logistyka
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2015
|
tom nr 3
3656--3668, CD 1
PL
Przyspieszone badania trwałościowe łożysk tocznych kulkowych zakończyły się uszkodzeniami bieżni wewnętrznej. W pracy przedstawiono symulację stanu naprężeń i odkształceń elementów łożyska w funkcji parametrów geometrycznych. Zachowano wymiary bazowe. Założono obciążenia zgodne z warunkami badań trwałościowych. Uwzględniono tolerancje osadzenia łożyska na czopie i w piaście. Analiza wyników symulacji wykazała niekorzystny skumulowany wpływ dużych naprężeń w próbie przyspieszonej (36% nośności dynamicznej) i naprężeń od wcisku bieżni wewnętrznej.
EN
Accelerated durability testing of rolling bearings ball ended with damage of their inner races. The paper presents the simulation of stress and deformation of the bearing as a function of geometrical parameters. It preserves the basic dimensions. There was established in accordance with the terms of the load durability testing. Includes the bearing tolerances on the journal and the hub. Analysis of simulation results showed a negative cumulative impact of large stresses in the accelerated test (36% of the basic dynamic load rating), and the stress of the interference of the inner race.
4
Content available remote Experimental and Simulation Studies on the Effect of Local Variations of the Hub Stiffness on Vibration Level in a System of Tapered Roller Bearings
100%
Ostapski W. , Dowkontt S.
Machine Dynamics Problems
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2009
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tom Vol. 33, No. 3
79-90
EN
In the paper, results of vibration measurements on brand new tapered roller bearings mounted to the support with a longitudinal channel are presented. The investigations were carried out in function of rotation speed of the shaft and axial loading applied to it. The bearings were lubricated by a solid oil. Numerical examinations were realised with the aid of CAD/CAE software and took into consideration real fit values, thermal and mechanical loadings of the bearing system which dad been recorded during experimental research.
5
Content available Integrals of the one-dimensional continuity equation
100%
Dowkontt S. , Dowkontt G.
TTS Technika Transportu Szynowego
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2016
|
tom R. 23, nr 12
77--81
EN
The authors analyze the method used by Cauchy and Lagrange to obtain the integral of continuity equation. The authors propose their own method of integration using Schwarz’ theorem. As a result, the authors obtain a greater number of possible solutions with a higher level of generality while also being able to identify the basic disadvantages of the Cauchy-Lagrangian method. Further, the authors conducted a detailed interpretation of the results of their solution.
6
On the velocity of spread for a one-dimensional unsteady flow
100%
Dowkontt S. , Dowkontt G. A.
Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska
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2017
|
tom z. 5/114
27--34
EN
Using the results of their earlier work the authors examine in details the issue of velocity of movement of flow front in one-dimensional transient flow. The authors identify the physical meaning of the symbols used and fragments of equations, as well define the basic properties and restrictions of the velocity of spread of the one-dimensional transient flow.
PL
Korzystając z wyników wcześniejszych swoich prac Autorzy rozpatrują szczegółowo zagadnienie prędkości przemieszania się czoła jednowymiarowego przepływu nieustalonego. Autorzy dokonują identyfikacji sensu fizycznego używanych symboli i fragmentów równań, a także określają podstawowe własności i ograniczenia prędkości rozprzestrzeniania się jednowymiarowego przepływu nieustalonego.
7
Content available remote Integrals of a One-Dimensional Continuity Equation Along the Trajectories of Liquid Planes
100%
Dowkontt S. , Dowkontt G.
Machine Dynamics Research
|
2018
|
tom Vol. 42, No. 4
17--31
EN
Authors presents the integration of a one-dimensional continuity equation of a new flow model, along the trajectories of liquid planes. That was made possible by expressing the fluid velocity u with partial derivatives of the function ζ - a function which expresses the position of liquid planes in the flow relative to the positions they occupied when the fluid was at rest. Consequently, the one-dimensional continuity equation has become integrable. This work was signaled in previous authors articles with a description of the process of obtaining formulas, that showing partial derivatives of the function ζ - by integrating a one-dimensional continuum equation along the fluid plane trajectory. In addition, this work is a complement of the previous works, in which the integral of the one-dimensional continuity equation along the straight lines x = const and t = const in the rectangular coordinate system x,t were derived. This work also includes the integral of the differential equation of liquid plane trajectories expressing the function η, which keeps a constant value along these trajectories. In addition, the content of the work consists a necessary explanations and, on the end, additional proof of the derived equations.
8
Content available Simulation and bench studies of the constructively and technologically modernized high performance piston aircraft engine. Stage I
80%
Ostapski W. , Wierzchoń T. , Rudnicki J. , Dowkontt S.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2017
|
tom Vol. 65, nr 1
93--105
EN
The paper presents an analysis of tribological wear of an assembly composed of cylinder liner and piston rings in a piston aircraft engine. In place of the previously used technology of gas nitriding of the cylinder liner (made out of 38CrAlMo6‒10 steel), formation of multi-component or composite layers by nitriding in plasma discharge environment was proposed. Also, a modification of the previously used chromium coating of the piston rings by plasma nitriding was proposed. A study on the structure and properties of surface layer diffusion manufactured by utilizing the phenomenon of cathode sputtering was carried out. Wear resistance tests were performed on a specially designed bench, with the use of isotope markers. Verification of each of the friction couples was based on using the wear of the ring as a function of the distance trip, and the roughness of the cylinder liner and ring.
9
Content available Erratum to: Simulation and bench studies of the constructively and technologically modernized high performance piston aircraft engine. Stage I
80%
Ostapski W. , Wierzchoń T. , Rudnicki J. , Dowkontt S.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2017
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tom Vol. 65, nr 2
273--275
EN
In Ostapski et al., Bull. Pol. Ac.: Tech 65(1), 93-105 (2017), doi: 10.1515/bpasts-2017-0012, an analysis of tribological wear of an assembly composed of cylinder liner and piston rings in a piston aircraft engine was presented. In place of the previously used technology of gas nitriding of the cylinder liner (made out of 38CrAlMo6-10 steel), formation of multi-component or composite layers by nitriding in plasma discharge environment was proposed. Also, a modification of the previously used chromium coating of the piston rings by plasma nitriding was proposed. A study on the structure and properties of surface layer diffusion manufactured by utilizing the phenomenon of cathode sputtering was carried out. Wear resistance tests were performed on a specially designed bench, with the use of isotope markers. Verification of each of the friction couples was based on using the wear of the ring as a function of the distance trip, and the roughness of the cylinder liner and ring. This note corrects flaws in illustrations published in the original paper.
10
Content available The vibration of prototype aircraft propeller speed reduction unit – test bench and FEM numerical simulation study
80%
Ostapski W. , Aromiński A. , Dowkontt S.
|
2014
|
nr 4
11
Content available Erratum to: Simulation and bench studies of the constructively and technologically modernized high performance piston aircraft engine. Stage I
80%
Ostapski W. , Wierzchoń T. , Rudnicki J. , Dowkontt S.
|
12
Content available The vibration of prototype aircraft propeller speed reduction unit – test bench and FEM numerical simulation study
80%
Ostapski W. , Aromiński A. , Dowkontt S.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2014
|
tom Vol. 62, nr 4
861--873
EN
The results of torsional shaft vibration bench tests for a prototype aircraft propeller speed reduction unit are presented in this paper. The study was conducted as a function of engine speed and lubrication conditions. 3D model of the propeller speed reduction unit was developed. By using the finite element method, normal modes frequencies were defined. The simulation was conducted both unloaded and loaded under nominal power conditions.
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