Galloping instabilities of Z-shaped shading louvers

Abstract

Modern design of civil constructions such as office blocks, airport terminal buildings, factories, etc. incorporates more and more environmental considerations that lead to, amongst other elements, the use of glazed fagades with shading devices to optimize energy consumption. These shading devices, normally slats or louvers, are very flexible structures exposed to the action of wind, and therefore aeroelastic effects such as galloping must be taken into account in their design. A typical cross-section for such elements is a Z-shaped profile made out of a central web and two side wings. The results of a parametric analysis based on static wind tunnel tests and performed on different Z-shaped louvers to determine translational galloping instability regions are presented in this paper.

Numerical Investigation of Galloping Instabilities in Z-Shaped Profiles

“…These configurations have been experimentally studied at IDR/UPM, Alonso et al [ 24 ]. The test facility is a two-dimensional open circuit wind tunnel where the test chamber dimensions are 0.15 m width, 0.90 m high, and 1.20 m long.…”

“…The aerodynamic loads were measured with a six-component strain-gauge balance. Additional details of the wind tunnel chamber and the experimental results can be found in [ 24 ]. The flow conditions were an inlet velocity of 25 m/s, a Reynolds number of 1.7 · 10 5 with the chord, c = 0.1 m, as reference length, and 4% of turbulence intensity.…”

“…Sun-shading louvers are examples where Z-shaped cross-sections may be found in slender structures susceptible to gallop. This type of Z-shaped cross-sections has also been experimentally analysed [ 24 ].…”

Investigación de fenómenos de galope en cuerpos de diversa sección transversal

“…El criterio de Glauert-Den Hartog nos da una condición necesaria para la aparición de galope. Para obtenerlo, nos fijamos en que la ecuación (15) es una ecuación diferencial lineal de segundo orden cuyo coeficiente de amortiguamiento relativo es:…”

“…El medio experimental que se ha empleado han sido los ensayos en túnel aerodinámico, y para ello se ha utilizado el túnel aerodinámico S1C del Instituto Universitario Ignacio Da Riva de la Universidad Politécnica de Madrid (IDR/UPM). Los resultados han sido publicados en Alonso et al [15]. Se trata de un túnel de circuito abierto, soplado de ventilador centrífugo.…”