EFFECT OF FLOW INCIDENCE AND REYNOLDS NUMBER ON LOW-SPEED AERODYNAMIC CHARACTERISTICS OF SEVERAL NONCIRCULAR CYLINDERS WITH APPLICATIONS TO DIRECTIONAL STABILITYnAND SPINNING

摘要

The aerodynamic characteristics of several non-circular two-dimensional cylinders with axes normal to the stream at various flow incidences (analogous to angles of attack of a two-dimensional airfoil and obtained by rotating the cylinders about their axes) for a range of Reynolds numbers have been deter¬mined from low-speed wind-tunnel tests. The results indicate that these parameters have rather large effects on the drag and side force developed on these cylinders. The side force is especially critical and very often undergoes a change in sign with a change in Reynolds number. Since the flow incidences correspond to combined angles of attack and sideslip in the crossflow plane of three-dimensional bodies, these two-dimensional results appear to have strong implications with regard to directional stability of fuselages at high angles of attack. These implica¬tions, along with those associated with the spin-recovery characteristics of aircraft, are briefly discussed.