Vortical structure in the wake of a transverse jet

Structural features resulting from the interaction of a turbulent jet issuing transversely into a uniform stream are described with the help of flow visualization and hot-wire anemometry. Jet-to-crossflow velocity ratios from 2 to 10 were investigated at crossflow Reynolds numbers from 3800 to 11400. In particular, the origin and formation of the vortices in the wake are described and shown to be fundamentally different from the well-known phenomenon of vortex shedding from solid bluff bodies. The flow around a transverse jet does not separate from the jet and does not shed vorticity into the wake. Instead, the wake vortices have their origins in the laminar boundary layer of the wall from which the jet issues. It is argued that the closed flow around the jet imposes an adverse pressure gradient on the wall, on the downstream lateral sides of the jet, provoking 'separation events’ in the wall boundary layer on each side. These result in eruptions of boundary-layer fluid and formation of wake vortices that are convected downstream. The measured wake Strouhal frequencies, which depend on the jet-crossflow velocity ratio, match the measured frequencies of the separation events. The wake structure is most orderly and the corresponding wake Strouhal number (0.13) is most sharply defined for velocity ratios near the value 4. Measured wake profiles show deficits of both momentum and total pressure

Wind towers - design of flange ring connection

Today, wind power is second largest available renewable resource of energy, with 870 TW (terawatts). Large wind farms, with hundreds of wind towers are big opportunity for steel production industry. Designers and manufacturers of wind towers pay special attention on every single detail, always looking for some new solutions, trying to reduce price of wind towers. Some of the most interesting design and manufacturing details are connections used to assemble sections of tubular steel towers supporting wind turbins. There is traditional and actually more used flange ring connection and on the other side, as a new proposal which is used more and more, friction connection. In this paper theoretic basis of design of flange ring connection of wind towers is give

Design of class 4 cross section in axial compression according to EUROCODE 3

In this paper theoretic basis of design of class 4 cross section in axial compression according to EN1993-1-5 is given. Design procedure is given as an flow chart and ilustrated with an worked example. Plate buckling is treated localy and globaly through the concept of effective cross sections. Interaction between plate-like and column-like behaviour of panels is carried out thought buckling reduction factors and final effective area of cross section

Wind towers - design of flange ring connection

Today, wind power is second largest available renewable resource of energy, with 870 TW (terawatts). Large wind farms, with hundreds of wind towers are big opportunity for steel production industry. Designers and manufacturers of wind towers pay special attention on every single detail, always looking for some new solutions, trying to reduce price of wind towers. Some of the most interesting design and manufacturing details are connections used to assemble sections of tubular steel towers supporting wind turbins. There is traditional and actually more used flange ring connection and on the other side, as a new proposal which is used more and more, friction connection. In this paper theoretic basis of design of flange ring connection of wind towers is give

Design of class 4 cross section in axial compression according to EUROCODE 3

In this paper theoretic basis of design of class 4 cross section in axial compression according to EN1993-1-5 is given. Design procedure is given as an flow chart and ilustrated with an worked example. Plate buckling is treated localy and globaly through the concept of effective cross sections. Interaction between plate-like and column-like behaviour of panels is carried out thought buckling reduction factors and final effective area of cross section

Stainless steel cross-section resistance according to continuous strength method

Continuous strength method is a contemporary approach to calculation of resistance of stainless steel cross-sections which has been recently developed at the Imperial College of London. The basis of the method is the continuous relation between the slenderness and strain capacity of a cross-section, nonlinear relation between the stress and strain and the strengthening effects of cold forming. In the paper are presented the fundamental rules for calculation of cross-section resistance according to continuous strength method; the comparative analysis of design resistance of the compressed cross-section was conducted through a numerical example according to this method and EN 1993-1-4

Stainless steel cross-section resistance according to continuous strength method

Continuous strength method is a contemporary approach to calculation of resistance of stainless steel cross-sections which has been recently developed at the Imperial College of London. The basis of the method is the continuous relation between the slenderness and strain capacity of a cross-section, nonlinear relation between the stress and strain and the strengthening effects of cold forming. In the paper are presented the fundamental rules for calculation of cross-section resistance according to continuous strength method; the comparative analysis of design resistance of the compressed cross-section was conducted through a numerical example according to this method and EN 1993-1-4

Uporedna analiza proračuna ekscentrično pritisnutih elemenata prema Evrokodu 3 i JUS-u

Evrokod 3 daje dva ravnopravna postupka proračuna interakcionih koeficijenata za proračun ekscentrično pritisnutih elemenata konstantnog jednodelnog poprečnog preseka. U ovom radu je data uporedna analiza rezultata proračuna ekscentrično pritisnutih elemenata prema Evrokodu 3 i važećem domaćem standardu. Interakcioni koeficijenti su sračunati prema alternativnim informativnim aneksima A i B, Evrokoda 3. Analizirani su rezultati šest numeričkih primera u kojima su varirane dužine elementa i vrednosti aksijalne sile pritiska

Uporedna analiza proračuna ekscentrično pritisnutih elemenata prema Evrokodu 3 i JUS-u

Evrokod 3 daje dva ravnopravna postupka proračuna interakcionih koeficijenata za proračun ekscentrično pritisnutih elemenata konstantnog jednodelnog poprečnog preseka. U ovom radu je data uporedna analiza rezultata proračuna ekscentrično pritisnutih elemenata prema Evrokodu 3 i važećem domaćem standardu. Interakcioni koeficijenti su sračunati prema alternativnim informativnim aneksima A i B, Evrokoda 3. Analizirani su rezultati šest numeričkih primera u kojima su varirane dužine elementa i vrednosti aksijalne sile pritiska

Opšta metoda za proračun bočnog i torzionog izvijanja elemenata čeličnih konstukcija

Beside standard procedure for stability design of structural elements in compression, bending, as well in compression and bending, Eurocode 3 offers posibility to make these calculations using finit element method through general method for lateral and lateral torsional buckling of structural elements. In this paper general method for lateral and lateral torsional buckling of structural elements is presented. Also, there is numerical example whose results are compared with results of Eurocodes alternative procedures and JUS