Applied Mechanics and Materials Vol. 617

Abstract: The paper presents an analysis of wind effects acting upon the structures having an irregular shape. The calculation of pressure distribution around the perimeter of irregularly-shaped structure is presented. The example shows the analysis techniques employing both values from the valid standards and results of a numerical calculation of flux of an irregularly shaped structure.

Abstract: This paper deals with determination of the parameters of simulated boundary layer in newly built Boundary Layer Wind Tunnel (BLWT). Short description of tunnel, measuring devices and possibilities of using of tunnel are mentioned here. All measurements, which were necessary for basic analysis of simulated natural wind, are shortly mentioned. The main part of this paper is devoted to additional measurements, which were necessary for detection of influences of boundary effects in part of the cross-section of tunnel where the calibration of Hot-wire anemometer is usually done. These boundary effects evoke deceleration of the wind velocity in given area. Description of additional measurements and obtained results are presented at the end of this paper.

Abstract: In the present article the response of layered plates to the effects of wind is analyzed. The computational model of layered plate meets the conditions of equilibrium shear stresses at the contact layers. The numerical experiment is applied to the layered glass plate with hinge supports at its edges. The dynamic effect of wind is analyzed in a dynamic calculation.

Abstract: This paper presents an analysis of the response of masts of power lines to wind gusts. The computational model of the masts is designed in two variants. The computational model of the first variant is the mast, in which the weight of insulators and conductors has been neglected. In the second variant, the effects of mass of insulators and conductors are modeled as a double pendulum. The values of wind pressure were obtained using a record of wind velocity.

Abstract: Flow characteristics contraction of rectangular cross-section are investigated numerically and experimentally so as to gain an additional insight into the contraction design. They observed velocity field and turbulent intensity in the area of contraction and downstream of it. Individual numerical models sofware Ansys Fluent are evaluated and compared with measurements in a wind tunnel.

Abstract: Wind tunnel measurements of vortex shedding behind cooling tower models were performed in VZLU. Two variants of cooling tower models were used, i.e. model with smooth wall outer surface and model with rough wall surface. Measurements were conducted using hot-wire anemometer. Time signal from the anemometer was transformed using Fast-Fourier routine into frequency spectrum. Measurements have shown significant differences between smooth and rough variant of model surface and dependency of vortex shedding frequency on Reynolds number.

Abstract: We study the response of a dynamic system to additive random noise and external determin- istic periodic force to investigate vibration of a slender prismatic beam in a cross flow with a turbulence component. The aim of the study is to find such parameter combinations, which should be avoided in practice to eliminate response amplitude increase due to the effect of the stochastic resonance. We assume the non-linear oscillator (beam) with one generalized degree of freedom in the divergence-like regime. It is described by the version of the Duffing equation. We conduct the theoretical investigation with the use of relevant Fokker-Planck equation together with verification by numerical simulation of corresponding stochastic differential system. Real characteristics of a sectional model, fixed in the special stand allowing the snap-through effect, in the wind tunnel are employed.

Abstract: For estimation of aerodynamic characteristics of cable-stayed footbridge deck a computational fluid dynamics (CFD) has been used. An incompressible fluid flow with Navier-Stokes equations has been applied. An adequate numerical model has been created to obtain accurate values of aerodynamic characteristics. Preliminary determination of simulation parameters have been estimated using laminar fluid flow model. Subsequently, Smagorinsky large-eddy simulation (LES) turbulent model has been applied with different simulation parameters to obtain converged values. The boundary layer separation regions and downwind vortex shedding has been observed.

Abstract: The article describes the effect of the crosswinds on the moving heavy road vehicles. It gives mathematical descriptions of two extreme situations originated from the crosswinds – side deflection from the directness and the rollover of the vehicles. It also analyzes the factors affecting the rate of the wind, as a cornering tire stiffness, instantaneous vehicle weight, axle load, the position of the center of gravity of the vehicle. Both situations present a greater risk for empty vehicles with tarpaulin superstructure, so some types of them are dealt.

Abstract: Accurate information about the wind resource and the wind energy potential is required for federal and local authority policy initiatives that will expand the use of wind energy. This paper presents the experience of creating an information-analytical system (IAS), based on GIS technologies, for wind energy potential (theoretical and practically achievable) of Leningrad and Pskov regions, located in the North-West of Russia. IAS consists of GIS database coupled with models for support of decision making for regional planning. The paper presents the general methodological approaches and possible practical difficulties during the creation of such systems.