Control of flow around square cylinders at incidence by using a rod


Sarioglu M. , Akansu Y., Yavuz T.

AIAA JOURNAL, vol.43, no.7, pp.1419-1426, 2005 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 7
  • Publication Date: 2005
  • Doi Number: 10.2514/1.9460
  • Title of Journal : AIAA JOURNAL
  • Page Numbers: pp.1419-1426

Abstract

Aerodynamic characteristics of a square cylinder at incidence were investigated experimentally in the wake of a small rod at a Reynolds number of 3.4 X 10(4). The dimensionless gap L/D was varied from 1.71 to 8.00. Depending on the spacing L/D, two flow patterns with and without vortex shedding from the rod were observed. Pressure measurements on the rod and square cylinder and hot-film measurements in the wake of the cylinder were carried out. The combined influences of the rod and angle of incidence on the pressure distributions and vortex-shedding phenomenon were investigated. Without the rod, as the incidence increases from 0 deg, the reattachment on the lower side surface of the square cylinder occurs at the vicinity of 13 deg, and this corresponds to a jump in the Strouhal number. However, when the rod was set upstream of the square cylinder, the reattachment occurs at smaller angles of incidence depending on L/D. At zero angle of incidence, the minimum value of drag on the square cylinder is obtained for L/D = 2.0 and produces a drag that is 30 % that of the square cylinder without rod. For L/D = 1.71, with increasing the angle of incidence C-D values approximate to those of the square cylinder without rod. In the case of L/D >= 2.7, there is a considerable decrease in C-D in the region 0 >= 10 deg; however, the effect of the rod on C-D decreases beyond 0 = 10 deg.