Spectral analysis of the boundary layer on a plunging airfoil

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.The effects of periodic unsteady flow through plunging motion on the boundary layer transition along the suction surface of a typical wind turbine blade section are experimentally investigated The state of the boundary layer at different conditions was determined using multiple hot-film sensors through the frequency domain analysis. The appearance of laminar/turbulent spikes at dominated frequencies revealed the boundary layer characteristics. Power spectral of the hot­-film signals showed that the transition locations as well as the separation region were a function of the reduced frequency and mean angle of attack.ej201

Computational study of a battle damaged finite aspect ratio wing

Numerical studies have been carried out on a battle damaged NACA 641-412 half wing of aspect ratio 8.2 at a Reynolds number of 5.5 x 105. The simulated gunfire damage was represented by a single hole with a diameter of 0.2 wing chord. The hole was centred at half chord and at spanwise locations of 450mm and 650mm from wing root. Computational Fluid Dynamics (CFD) results have been compared with experimental data and a general overall good agreement has been obtained, in the flow features introduced by the damage. Furthermore, the flow field inside the damage hole and in the region downstream of the jet have been analysed in more detail using CFD

Low reynolds number airfoil optimization for wind turbine applications using genetic algorithm

Optimization of a low Reynolds number airfoil for use in small wind turbines is carried out using a Genetic Algorithm (GA) optimization technique. With the aim of creating a roughness insensitive airfoil for the tip region of turbine blades, a multi-objective genetic algorithm code is developed. A review of existing parameterization and optimization methods are presented along with the strategies applied to optimize the airfoil in this study. A composite Bezier curve is used to parameterize the airfoil. The resulting airfoil, the USPT2 has a maximum thickness of 10% and shows insensitivity to roughness at the optimized angles and at other angles of attack as well. The characteristics of USPT2 are studies by comparing it against the popular SG6043 airfoil. While a slight loss in lift is noticed for both airfoils, the drag increments due to early transition are noticeable as well. The airfoil is also studied using CFD and wind tunnel experiments during free and forced transition. The USPT2 airfoil will be useful in small wind turbines for locations where blade soiling is likely or where other flow phenomena may cause early transition of the boundary layer

Small molecule antagonists of melanopsin-mediated phototransduction

Melanopsin, expressed in a subset of retinal ganglion cells, mediates behavioral adaptation to ambient light and other non-image forming photic responses. This has raised the possibility that pharmacological manipulation of melanopsin can modulate several CNS responses including photophobia, sleep, circadian rhythms and neuroendocrine function. Here we describe the identification of a potent synthetic melanopsin antagonist with in vivo activity. Novel sulfonamide compounds inhibiting melanopsin (opsinamides) compete with retinal binding to melanopsin and inhibit its function without affecting rod/cone mediated responses. In vivo administration of opsinamides to mice specifically and reversibly modified melanopsin-dependent light responses including the pupillary light reflex and light aversion. The discovery of opsinamides raises the prospect of therapeutic control of the melanopsin phototransduction system to regulate light-dependent behavior and remediate pathological conditions