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Your search keyword '"Štigler, Jaroslav"' showing total 4 results
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4 results on '"Štigler, Jaroslav"'

1. Overshot water wheel efficiency measurements for low heads and low flowrates

Author

Štigler Jaroslav

Subjects
Physics, QC1-999
Abstract

Utilizing of low renewable energy sources is an actual topic nowadays. This paper is focused on the locations with the low hydro-energy potential. It means locations with a head about 1m and flow rates about tens of litres per second. Hydro turbines for such parameters belong to the pico-turbines. It is not easy to design the hydro-turbine for such parameters with an acceptable efficiency. One of the possibilities is to use a water wheel. It is possible to find in a literature that the efficiency of overshot water wheels achieves 85%. This is the very good efficiency. It is not so easy to find some experimental data which proves this statement. Aims of this work are to design a simple manufactured overshot water wheel, measure the hydraulic efficiency of this wheel for wide range of parameters, finding an effect of the leading edge adjusting and the effect of the channel outflow edge position on the water wheel efficiency.

Published
2022
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3. Bingham liquid flow between two cylinders induced by inner ring rotation

Author

Fialová Simona and Štigler Jaroslav

Subjects
Materials science, media_common.quotation_subject, Rotational speed, Mechanics, Radius, Concentric, Rotation, Physics::Fluid Dynamics, Fluid dynamics, Newtonian fluid, Astrophysics::Earth and Planetary Astrophysics, Eccentricity (behavior), Bingham plastic, media_common
Abstract

This paper deals with the fluid flow between two cylinders induced by inner ring rotation. The gap width between the cylinders, in case that they are both concentric, is 1mm, the gap and inner ring radius ratio 0.013 and the radius ratio 0.987. Attention is focused on rotation speed and eccentricity influence on the flow. Calculations were done for both Newtonian liquid and Bingham plastic liquid with the yield stress threshold 50 Pa.

Published
2017

4. Contribution to investigation of turbulent mean-flow velocity profile in pipe of circular cross-section

Author

Štigler Jaroslav

Subjects
Physics::Fluid Dynamics, Cross section (physics), Classical mechanics, Density distribution, Basis (linear algebra), Flow (mathematics), Turbulence, Mean flow velocity, Mechanics, Vorticity, Mathematics
Abstract

This paper deals with problem of mean-flow velocity profiles for a turbulent flow in a pipe of circular cross-section. There are mentioned some very well-known analytical formulas of mean-flow velocity profiles and also new formulas based on the vorticity density distribution over the pipe cross-section. All of them are analyzed and compared with a measurement. There is given an explanation of all coefficients and their physical meaning. Some formulas for the coefficients are improved on the basis of experimental data. There is also a discussion about the precision of all mean-flow velocity profiles and there are given some ideas why they don’t fit well in some regions of flow at the end of the paper.

Published
2016

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