Low-Speed Aerodynamic Analysis Using Four Different Turbulent Models of Solver of a Wind Turbine Shroud

This study presents the effect of four different turbulent models of solver on the aerodynamic analysis of a shroud at wind speed below 6 m/s. The converting shroud uses a combination of a cylindrical case and an inverted circular wing base which captures the wind from a 360° direction. The CFD models used are: the SST (Menter) k-ω model, the Reynolds Stress Transport (RST) model, the Improved Delay Detached Eddies Simulation model (IDDES) SST k-ω model and the Large Eddies Simulation Wall Adaptive model. It was found that all models have predicted a convergent surface pressure. The RST, the IDDES and the WALE LES are the only models which have well described regions of pressure gradient. They have all predicted a pressure difference between the planes (1–5) which shows a movement of the air from the lower plane 1 (inlet) to the higher plane 5 (outlet). The RST and IDDES have predicted better vorticities on the plane 1 (inlet). It was also found that the model RST, IDDES, and WALE LES have captured properly the area of turbulences across the internal region of the case. All models have predicted the point of flow separation. They have also revealed that the IDDES and the WALE LES can capture and model the wake eddies at different planes. Thus, they are the most appropriate for such simulation although demanding in computational power. The movement of air predicted by almost all models could be used to drive a turbine.

The theatre of Aitolian Makyneia

Remains of a recently excavated small theatre at the foot of a fortified hill, identified with Aitolian Makyneia, were studied on the basis of electronic surveying, CAD, graphical and analytical approximation techniques. This theatre, of the 4th or 3rd century BC, partly excavated on the hillside and built of large sandstone slabs, has an unusual shape, with its koilon consisting of a curvilinear wing of 14 rows of seats and an adjacent linear wing of three rows of blocks forming a single-row proedria. Geometric modelling of the theatre remains on the basis of graphical, and especially of analytical techniques, indicates that the circular wing of the koilon consists of equidistant, concentric rows of seats based on a design arc of 90° for the 1st row, with the corresponding chord normal to the linear wing. Possible poor remains of a skene were found oblique (81°) to the linear wing.

Exact Two-Dimensional Analysis of Circular Disk Spiral Groove Bearing (Part I)

Basic equations and idea of the method are described concerning the new two-dimensional theory of thin fluid film of spiral groove bearings. Two-dimensional inviscid flow theory of circular wing lattice is the basis of the proposed method. Detailed technique to perform numerical calculation has been established utilizing singularity method. Two-dimensional pressure formation of the fluid film is calculated together with load carrying capacity.