This paper treats the flow around a circular cylinder with a step in a uniform flow. Vortex shedding frequency was measured for various diameter ratios d/D (0 to 1.0), length-diameter ratios L/D (10 to 27) and Reynolds numbers Re (800 to 104). Strouhal number St decreases with decreasing d/D and L/D, especially at low Reynolds numbers. The decrease in measured shedding frequency is explained by the effects of the downwash of a free stream from the step. The structure of vortex street was observed by visual means and six hot-wire anemometers. The three-dimensional effects due to the step were studied and Y-shape connection of vortex filaments was found for d/Dg0.8.

On Vortex Shedding from Circular Cylinder with Step

Flow pattern and heat transfer past two tandem arranged cylinders with oscillating inlet velocity

Many studies have investigated natural convection heat transfer from the outside surface of horizontal and vertical cylinders in both constant heat flux and temperature conditions. However, there are poor studies in natural convection from inclined cylinders. In this study, free convection heat transfer was examined experimentally from the outside surface of a cylinder for glycerol and water at various heat fluxes. The tests were performed at 10 different inclination angles of the cylinder, namely, φ = 0°, 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°, measured from the horizon. Our results indicated that the average Nusselt number reduces with the growth in the inclination of the cylinder to the horizon at the same heat flux, and the average Nusselt number enhanced with the growth in heat flux at the same angle. Also, the average Nusselt number of water is greater than that of glycerol. A new experimental model for predicting the average Nusselt number is suggested, which has a satisfactory accuracy for experimental data.

S. B. Chen

Papers

Three-dimensional vortex flow near the endwall of a short cylinder in crossflow: Uniform-diameter circular cylinder