Array Geometry Effects on Vortex Shedding and Instability in Heat Exchanger Tube Bundles

Abstract

<p>Eight tube arrays were tested to determine the effect of tube pattern and pitch on excitation phenomena in tube arrays in crossflow. These consisted of two different pitch-to-diameter ratios for each of the four standard heat exchanger tube array configurations. Measurements of vortex shedding frequencies showed that laminar vortex shedding may occur for some tube arrays at low Reynolds numbers and is associated with very high Strouhal numbers. Some arrays showed multiple values of Strouhal numbers at moderate Reynolds numbers, and over a small range of pitch ratios. Quite good agreement is found with some of the published results. Also, an improved correlation of the existing Strouhal numbers is obtained. The effect of tube pattern and pitch on the critical flow velocities at low damping parameter was determined. The results were used with other available results to determine the variation of the reduced velocity with the damping parameter for the different arrays tested.</p>