Topic
Freestream
About: Freestream is a research topic. Over the lifetime, 3428 publications have been published within this topic receiving 56147 citations.
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TL;DR: In this article, the results from a set of incompressible, shear-layer flow experiments, at high Reynolds number (Re_δ ≡ ρΔUδ_T(x)/μ ≃ 2×10^5), in which the inflow conditions of shearlayer formation were varied (δ is the temperature-rise thickness for chemically-reacting shear layers).
Abstract: We report on the results from a set of incompressible, shear-layer flow experiments, at high Reynolds number (Re_δ ≡ ρΔUδ_T(x)/μ ≃ 2×10^5), in which the inflow conditions of shear-layer formation were varied (δ_T is the temperature-rise thickness for chemically-reacting shear layers). Both inert and chemically-reacting flows were investigated, the latter employing the (H_2+NO)/F_2 chemical system in the kinetically-fast regime to measure molecular mixing. Inflow conditions were varied by perturbing each, or both, boundary layers on the splitter plate separating the two freestream flows, upstream of shear-layer formation. The results of the chemically-reacting ‘flip experiments’ reveal that seemingly small changes in inflow conditions can have a significant influence not only on the large-scale structure and shear-layer growth rate, as had been documented previously, but also on molecular mixing and chemical-product formation, far downstream of the inflow region.
110 citations
TL;DR: In this paper, a method to determine the position of the separation point on the rotating blade, based on the chordwise pressure gradient in the separated area, is proposed to evaluate rotation and turbulence effects on a wind turbine blade aerodynamics, focusing particularly on stall mechanisms.
110 citations
TL;DR: In this article, an oscillating freestream over a stationary S809 airfoil is simulated numerically using ANSYS Fluent 12.1 and compared with aerodynamic coefficients from existing experimental and semi-empirical data.
108 citations
TL;DR: In this article, the effectiveness and heat transfer coefficient of a film cooling system in which air was used both for the film and for the freestream fluids were investigated. But, as in past experience with such systems, separate specifications were needed for injection velocities greater and less than the free-stream velocity.
Abstract: Experimental results are presented for the effectiveness and heat- transfer coefficient of a film cooling system in which air was used both for the film and for the freestream fluids. Injection occurred at a single tangential slot near the leading edge of the plate, and the slot size was varied. All flows were turbulent, and the injection velocities covered a range from much less to much greater than the free-stream velocity. Correlations were realized for both the effectiveness and the heat-transfer coefficient and, as in past experience with such systems, separate specifications were needed for injection velocities greater and less than the free-stream velocity. (auth)
108 citations
TL;DR: In this article, the authors investigate energy harvesting from vortex-induced vibrations of a freely moving rigid circular cylinder with a piezoelectric transducer attached to its transverse degree of freedom and determine the power levels that can be generated from these vibrations and variations of these levels with the freestream velocity.
Abstract: We investigate energy harvesting from vortex-induced vibrations of a freely moving rigid circular cylinder with a piezoelectric transducer attached to its transverse degree of freedom. The power levels that can be generated from these vibrations and variations of these levels with the freestream velocity are determined. A mathematical model that accounts for the coupled lift force, cylinder motion, and harvested voltage is presented. Linear analysis is performed to determine the effect of the electrical load resistance of the transducer on the natural frequency of the cylinder and the onset of synchronization (the shedding frequency is equal to the cylinder oscillating frequency) region. The impact of the nonlinearities on the cylinder response and harvested energy is investigated. The results show that the load resistance shifts the onset of synchronization to higher freestream velocities. For two different system parameters, the results show that the nonlinearities result in a hardening behavior for some values of the load resistance.
106 citations