This paper analyses a set of velocity time histories which were obtained at fixed point in the bottom boundary layer tidal stream, 5 m from seabed, and where mean flow reached 2.5 s −1 . Considering two complete cycles near spring tide, streamwise turbulence intensity during non-slack was found to be approximately 12–13%, varying slightly between flood ebb tides. The ratio that transverse vertical intensities is typically 1 : 0.75 0.56, respectively. Velocity autospectra computed maximum...

An improved characterisation of the hydrodynamic blade loads due to onset turbulence is essential in order mitigate premature failures, reduce excessive levels conservativeness and ultimately ensure commercial viability tidal turbines. The literature focussing on fast flowing streams unsteady that are subsequently imparted rotors has previously been very limited. However, increased activity energy community led new investigations insights which reported this paper. It found through use...

An improved characterisation of the unsteady hydrodynamic loads on tidal turbine blades is necessary to enable more reliable predictions their fatigue life and avoid premature failures. To this end, paper presents a set blade-root bending moment responses for scale-model subjected an planar forcing in towing tank. In cases where boundary layer was believed be attached outer sections blade, out-of-plane amplitude flow up 15% greater than corresponding load measured steady exhibited phase-lead...

A three-dimensional numerical simulation of an interrupted microchannel heat sink is performed to investigate the pressure drop and transfer characteristics a nanofluid flow. In first part effect two different rib shapes on flow studied find optimum design. this water used as working fluid. For second present work, Al2O3/water with volume fractions modeled fluid, its performance compared water. Analysis shows that using ellipse ribs results in better rather than diamond no ribs. It was also...

Thermal and hydraulic characteristics of laminar nanofluid flow in square microchannel with longitudinal inner fins are numerically investigated. The external walls heated at constant heat flux four rectangular fixed on the internal walls. Four different types used as working fluids which SiO 2 , Al O 3 CuO ZnO dispersed pure water base fluid. Different volume fractions 1–2% nanoparticle diameters 30–60 nm employed. results show that has highest transfer rate among all tested nanofluids....

An analytical model for synthetic jet actuation based on the laws of fluid dynamics is presented. A actuator consists a cavity with driven wall and an orifice. Under actuation, oscillated, resulting in oscillatory flow through In model, modeled as single-degree-of-freedom mechanical system, which pneumatically coupled to cavity-orifice arrangement acting Helmholtz resonator. The latter was using unsteady form continuity Bernoulli equations loss term. validated against experimental data...

Small unmanned aerial vehicles (UAVs) are becoming more common as electronic systems decrease in size and weight. These aircraft fly below a Reynolds number of 250,000, where, clean flow, the wing boundary layer undergoes laminar-to-turbulent transition for significant portion chord. However, many UAVs at low altitude, where levels turbulence encountered due to terrain roughness. The present study was carried out understand how this turbulent flow changes performance UAV wing—in particular,...