Experimental Study On Heat Transfer Enhancement And Pressure Drop Characteristics Of Oblique-cut Semi-elliptic Cylinder Shell Vortex Generators

The experimental apparatus used to study the heat transfer enhancement and pressure drop characteristics of the vortex generators (VGs) were designed and established, and oblique-cut semi-elliptic cylinder shell, oblique-cut semi-circular cylinder shell VGs were newly developed. A pair of single-row different shapes VGs were selected to carry out comparative experiments with Reynolds number (Re) ranging from 700 to 26800 in a rectangular channel. The results showed that oblique-cut semi-elliptic cylinder shell has the best comprehensive performance with the highest local heat transfer coefficients 5.7% higher and pressure drop (which was similar as oblique-cut semi-cylinder) 37.9% lower than rectangular winglet for Re=20000. The optimizing experiments were further performed by changing the elevation angle a, attack angleβ, spacing of the leading-edges S, and the arrangement under various operating conditions and so on. The results indicated that the optimal parameter are a=12°,β=60°and S=20mm under the present conditions. It is suggested that the oblique-cut semi-cylinder shell is a kind of VGs with efficient heat transfer enhancement but low pressure drop. Oblique-cut semi-cylinder shells are relatively simpler and more convenient to be machined than the oblique-cut semi-cylinders.