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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.

Basic aim of this paper is to bring out the characteristics of the T-junctions. T-junction consists of the one straight pipe and the adjacent branch which can be inclined under various angle γ. These characteristics were done for the T-junctions with equal diameters of all branches and for five different angles of the adjacent branch. There is also included comparison between characteristics obtained by the numerical calculation and by the experiment in this paper.

Abstract: This paper deals with the fluid flow in the T-junction with the 90°C angle of the adjacent branch and with the 50mm diameter of each branch. The flow is organized as a combining flow. It means that there are two inlet branches and only one outlet branch. There are two possible kinds of the flow combinations for this T-junction. The CFD calculations and the PIV measurements were done for both flow combinations. Its comparison is presented in this paper. [Copyright &y& Elsevier]

The derivation of the mean velocity profile for a given vorticity distribution over the pipe cross-section is presented in this paper1. The velocity profile and the vorticity distribution are axisymmetric, which means that the radius is the only variable. The importance of the vortex field for the flow analysis is discussed in the paper. The polynomial function with four free parameters is chosen for the vorticity distribution. Free parameters of this function are determined using boundary conditions. There are also two free exponents in the polynomial. These exponents are determined based on the comparison of this analytical formula with experimental data. Experimental data are taken from the Princeton superpipe data which consist of 26 velocity profiles for a wide range of Reynolds numbers (Re). This analytical formula for the mean velocity profile is more precise than the previous one and it is possible to use it for the wide range of Reynolds number <31,577; 35,259,000>. This formula is easy to use, to integrate, or to derivate. The empirical formulas for the profile parameters as a function of Re are also included in this paper. All information for the mean velocity profile prediction in the mentioned Re range are in the paper. It means that it is necessary to know the average velocity v(av), the pipe radius R, and Re to be able to predict the turbulent mean velocity profile in a pipe. [ABSTRACT FROM AUTHOR]