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Utility-scale projects for hydrokinetic energy extraction from rivers, tidal or ocean currents could include tens to hundreds of turbines in densely-packed hydro farms. The aim of the present paper is to obtain a better understanding of the power production and wakes generated by several devices modeling a straight array of horizontal-axis water turbines in a hydro farm. To accomplish this, stereo particle image velocimetry experiments were carried out to measure the flow properties upstream and downstream of the devices in the array including up to four elements. The study also provides measured values of power and thrust coefficients of the model turbines using strain gauges installed directly on the rotor shaft. The current laboratory experiments provide data on the efficiency of water turbines in arrays or in a hydro farm arranged in a single line.

Oscillations of an isolated thin magnetic tube at various depths of the convective zone and in the atmosphere of the Sun are investigated in the present work in the approximation of ideal magnetic gas-dynamics. These oscillations are the source of generation of acoustic waves whose transition in weak shock waves provides anomalous heating of the solar atmosphere. The modes of small-amplitude linear oscillations at various depths of the convective zone are investigated. The loss of stability of equilibrium of the magnetic tube which is initially at rest in the convective zone as well as the nonlinear large-scale oscillations of the tube and tube emergence into the solar atmosphere are independently investigated. The results obtained are fundamental for research of sunspot generation and physics of solar activity, they are important for analysis of generation and tine evolution of global magnetic structures, solar wind, and some other astrophysical phenomena., See also ADM001433. International Conference on Methods of Aerophysical Research (11th). Held in Novosibirsk, Russia on 1-7 Jul 2002. Prepared in cooperation with Russian Academy of Sciences Inst. of Thermophysics, Novosibirsk, Russia.

The low chromosphere heating by the series of shock waves is investigated. Waves are initially generated in the solar photo sphere. Due to propagation in the strong stratified solar atmosphere the waves are overturning to the shock waves. The goal of present paper is to investigate it using 2D approximation. To describe the solar atmosphere one-fluid hydrodynamics with taken into consideration radiative heat transfer and absence of the thermodynamic equilibrium is used. Computer modeling is performed for one-and two-dimensional formulation of problem. The results obtained are important for understanding the physics of star atmospheres reaction on the dynamical disturbances like flares mass surges and heating by penetrating convection., See also ADM001433. International Conference on Methods of Aerophysical Research (11th). Held in Novosibirsk, Russia on 1-7 Jul 2002. Prepared in cooperation with Russian Academy of Sciences.