Analysis of the Behavior in the Wind Tunnel of an Experimental Model of Savonius with Interlocking Cups with the Classic Ones with 2, 3 and 4 Semi-Cylindrical Cups

The paper is based on experiments conducted on the wind tunnel at low wind speeds (<9.5 m/s), on an experimental model of S-rotor wind turbine type with four blades and a D/H ratio of 1. Semi-cylindrical cups opposite 180 degrees are aerodynamically coupled by overlap and with an air passage gap to equalize the pressures. The formed channel is shaped to allow the same for pairs of blades at 90 degrees. The experimental model has an area of 0.025 m2 which represents 10% of the surface of the measuring section of the wind tunnel (0.25 m2). The behavior of the experimental model was compared with the experimental models of S-rotor with 2, 3 and 4 semi-cylindrical cups, with the same interception surface. The results confirm the better start of the experimental model by reducing dead zones and operating more evenly and stably over a longer range of wind speeds. The results confirm the validity of the proposed concept of interwoven aerodynamic coupling of semi-cylindrical cups.

Impact of Geometrical Imperfections on Estimation of Buckling and Limit Loads in a Silo Segment Using the Vibration Correlation Technique

The paper examines effectiveness of the vibration correlation technique which allows determining the buckling or limit loads by means of measured natural frequencies of structures. A steel silo segment with a corrugated wall, stiffened with cold-formed channel section columns was analysed. The investigations included numerical analyses of: linear buckling, dynamic eigenvalue and geometrically static non-linear problems. Both perfect and imperfect geometries were considered. Initial geometrical imperfections included first and second buckling and vibration mode shapes with three amplitudes. The vibration correlation technique proved to be useful in estimating limit or buckling loads. It was very efficient in the case of small and medium imperfection magnitudes. The significant deviations between the predicted and calculated buckling and limit loads occurred when large imperfections were considered.

Cold Formed Steel Channel Sections with Flange Stiffeners

In recent years the utilization of cold formed steel has been redoubled. This is because high strength to weight ratio of the cold formed steel. The thicknesses cold formed steel members usually range from 0.3 mm to 6.35 mm. The most used cold formed sections are C and Z sections. These sections can be used as secondary beams (purlins) for roof covering, side girts, decks, and panels. Scope of this present study is to investigate the effect on load carrying capacity of cold formed channel sections provided with flange stiffeners. In this project, eighteen numbers of channel sections were analysed by keeping the height to thickness ratio (h/t) as constant and by varying flange width to thickness ratio (b/t) using Ansys 14.0. The h/t ratio and b/t ratio considered are 50 and 25, 35, 45 respectively. The thickness and span of all specimens were kept as 2 mm and 1500 mm respectively. Simply supported boundary condition and two points loading was adopted for both the numerical and experimental analysis. Three numbers of channel sections were fabricated and tested experimentally to check the consistency of results with numerical analysis. The ultimate load and deformed shape of three specimens were obtained from experimental results are compared with the analytical results acquired from Ansys 14.0