Detailed Measurements on a Circular Cylinder in Cross Flow

Abstract

ASERIES of wind tunnel tests covering a range of Mach numbers and Reynolds numbers in subsonic and transonic flows was conducted on a circular cylinder placed normal to the flow. Form drag coefficients were determined from surface pressure measurements and displayed as a function of Mach number to show the transonic drag rise phenomenon. Buried wire gages arranged on the model surface were used to measure skin friction distributions and vortex shedding frequencies at different flow conditions. It was found that detectable periodic shedding ceases above M= 0.9. The measured skin friction distributions indicate the positions of mean separation points clearly; these values are documented for different flow conditions. Contents Flow past circular cylinders is of interest because of its relevance to various problem areas such as aerodynamics of aircraft and missiles at high angles of attack, 1>2 wind effects on tall chimney structures, flow past tube banks of heat exchangers, hydrodynamics of towing and mooring cables for undersea applications, etc. Recently, there has been some interest in developing numerical methods for solving flow past circular cylinders so that predictions can be made for flow regimes that cannot be easily attained in test facilities. Success in such attempts depends heavily on extended flow documentation, especially on boundary-laye r development. At present, only very limited data exist in this regard. The present investigation was concerned with three main features of flow past cylinders: skin friction distribution, form drag coefficients, and vortex shedding frequencies. All tests were conducted in the 2-x2-ft (61x61-cm) transonic wind tunnel at NASA Ames Research Center. Perforated walls in the test section allowed good control of Mach number through the transonic range. Different values of Reynolds numbers were achieved by altering the pressure level in the