FLOW VISUALIZATION AND SURFACE PRESSURE MEASUREMENT ON 2 TUBES IN AN IN-LINE ARRANGEMENT

An experimental investigation was carried out on the flow around and the pressure on two tubes (circular cylinders) rigidly mounted in an inline or tandem arrangement. Flow visualizations were performed in a subcritical Reynolds number range, 3.3 X 10(3) < Re < 12 X 10(3), for dimensionless tube spacings in the range of 1.25 < SID < 4.0, using a smoke-wire technique. Fluctuating surface pressures were recorded by a microphone in a pinhole arrangement. Pressure measurements were performed in the Reynolds number range 3 X 10(3) < Re < 4 X 10(4) for three different dimensionless spacings between the tubes, S/D = 1.25, 2.0, and 4.0. The flow visualizations and pressure measurements clearly revealed that the flow depends on the Reynolds number and tube spacing. Alterations in the flow pattern are reflected in the mean and rms pressure distributions on the tube surfaces and the Strouhal number.