A class of adaptive disturbance tracking controllers (ADTCs) is augmented with disturbance and state estimation and adaptive state feedback, in which a controller and estimator, which are designed on the basis of a lower-order model, are used to control a higher-order nonlinear plant. The ADTC requires that the plant be almost strict positive real (ASPR) to ensure stability. In this paper, we s...

Draft tube of Francis type hydraulic turbine usually consists of: cone, elbow and diffuser. On the contrary, in some power stations an extra pipe should be added to the draft tube at the bottom of cone because of installation limitation. In this paper, this special case has been numerically studied. To this end CFD analysis was applied to simulate all parts of hydraulic turbine. A homogeneous m...

Marine current turbine commercial prototypes have now been deployed and arrays of multiple turbines under design. The tidal flows in which they operate are highly turbulent, but the characteristics of the inflow turbulence have not being considered in present design methods. This work considers the effects of inflow turbulence on the wake behind an actuator disc representation of a marine curre...

Flanged diffuser can improve hydrokinetic turbine efficiency. However, in the current literature it is still not clear if flange allows possibility of cavitation on its structure, and whether support high pressure variation. This work presents a Computational Fluid Dynamics (CFD) study effect flanged diffuser. The water flow through was evaluated using Reynolds Averaged Navier Stokes approach c...

Developing reliable tidal-energy turbines of a large size and capacity links to preservation the structural safety stability blades. In this study, bidirectional fluid–structure coupling method was applied analyze hydrodynamic performance characteristics blade tidal-stream turbine. Analyses were conducted on transient stable stresses, fatigue, deformations under influence water depth turbine ro...

Abstract: A refined assessment of tidal currents variability is a prerequisite for successful turbine deployment in the marine environment. However, the numerical evaluation of the tidal kinetic energy resource relies, most of the time, on integrated parameters, such as the averaged or maximum stream powers. Predictions from a high resolution three-dimensional model are exploited here to charac...

It is quite well known that the diffusers are required for efficient conversion of the dynamic head generated by the impeller in a centrifugal fan. Hence the flow into the diffuser passage plays a crucial role in determining the efficiency of conversion. The flow in the region bounded by the impeller exit and the diffuser entry i.e. the radial clearance space is generally considered to be highl...

One possible way to harness wind more efficiently in low-wind urban areas is place turbines inside a duct. A known issue of such approach due the flow separation that can occur at diffuser walls. This be avoided using channelled structure consisting duct and flap, also as multi-slot system. The present work describes effects flap geometry on turbine performance, through computational fluid dyna...