Wyniki wyszukiwania - BazTech

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A Mean-Line Flow Model of Viscous Liquids in a Vortex Pump

Li Wenguang

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2022

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Vol. 26, No 2

1--18

EN

The axial, radial and tangential velocity profiles of six fluids were extracted from computational fluid dynamics simulation results at points in a pump chamber 1 mm distant from the blades in a vortex pump at the specific speed of 76. The critical radius was specified in the axial velocity radial profiles to determine the impeller inlet and outlet at six viscosities and part-load, design, and over-load points. A mean-line flow model and hydraulic loss model were built from the profiles. The incidence, incidence loss in the inlet, deviation angle, and slip factor in the outlet were calculated. The impeller theoretical head, pump hydraulic efficiency and volumetric efficiency were analyzed. It was shown that the axial, radial and tangential velocity profiles relate closely to the flow rate as usual, but also the viscosity, especially at low flow rates and in the inlet. The low flow rate and viscosity lead to near zero axial and radial velocities, a faster tangential velocity than the blade speed, negative incidence, and a small incidence loss coefficient in the inlet. The dimensionless critical radius ranged within 0.77–0.89 and reduces with the increasing flow rate and viscosity. The mean slip factor is between 0.11 and 0.20 and rises with the increasing flow rate and viscosity. The mean incidence loss coefficient is within 0.0020–0.15 and augments with the increasing flow rate but increases with the decreasing viscosity under part-load conditions. The theoretical head estimated by using the fluid tangential velocity between the outlet of the impeller and the inlet of the chamber is more reasonable.

2

Analysis of the dynamics of vehicle motion in case of sudden braking connected with damage of the tire

Kovalev Valery, Blyankinshtein Igor, Morozov Dmitry, Kazantsev Andrew

Transport Problems

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2020

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T. 15, z. 1

15--23

EN

One of the urgent problems to be solved in the analysis of road traffic accidents is the calculation of vehicle speed at the time of sudden braking. This makes it possible to determine the dynamics of further movement of the vehicle and to determine the technical ability of the driver to prevent a traffic collision. The article presents a metho employed in calculating the speed of the car at the time of sudden braking and determines the dynamics of movement up to its complete standstill. The correct calculation of the speed of movement allows us to obtain the reliability of the restored co-existence, as well as data for an objective analysis of the road traffic accident.

3

Zastosowanie modelu Eulera do wyznaczania kątów odchylenia strug za płatem

Iglewski T., Goraj Z.

Prace Instytutu Lotnictwa

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2000

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Nr 2 (161)

70-77

PL

Zastosowano przestrzenne równania Eulera do modelowania ruchu płynu nielepkiego wokół izolowanego płata. Przedstawiono sposób rozwiązywania tych równań metodą różnic skończonych na niejednorodenj siatce otaczającej opływany obiekt. Zaprezentowano możliwość stosowania siatek wieloblokowych jako sposób opisu skomplikowanych geometrii. Przedstawiono metodę łączenia siatek wieloblokowych. Równania Eulera wykorzystano do wyznaczania kąta odchylenia strug w przestrzeni za płatem. Otrzymane wyniki dla różnych geometrii porównano z wynikami z innych źródeł: tablic inżynierskich, wzorów analitycznych i danych eksperymentalnych.

EN

Three dimensional Euler equations in the conservative form were used to simulate flow field around separated wing. Finite-difference computation method, based on Mac Cormack technique for non-uniform, structured multiblock grig system is presented and applied to describe a wing of an arbitrary planform. This method was used to simulate downwash for several different wing configurations. Simulation results were compared to results from other sources as data sheets, analytical formulae and experimental data.

4

Ocena układu bryły trójpowierzchniowej z uwzględnieniem kąta odchylenia strug

Danilecki S.

Prace Instytutu Lotnictwa

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2000

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Nr 3-4 (162-163)

49-52

PL

Przedstawiona metoda uzupełnia zaproponowane wcześniej przez autora kryterium oceny porównawczej brył płatowca o kąt odchylenia strug. Metoda pozwala zminimalizować wartość oporu indukowanego, obliczonego z uwzględnieniem kąta odchylenia strug. Metoda adresowana jest do brył aerodynamicznych w układzie trójpowierzchniowym, dla których kąt odchylenia strug jest istotny.

EN

Presented method suplements comparison criterion of airframe shape (formerly presented by author), with effect of airstream downwash angle. Method allows to minimalise the value of inductive drag, computed with downwash angle consideration. Method adresses aerodynamic shapes in three-plane airframe acheme, for which the effect of airstream downwash angle is essential.