EXPERIMENTAL STUDY ON STRUCTURE OF GAS FLOW IN TUBE BANKS WITH TUBE AXES NORMAL TO FLOW - 1. KARMAN VORTEX FLOW FROM TWO TUBES AT VARIOUS SPACINGS.

Abstract

A gas flow in and behind tube banks with tube axes normal to the gas flow is highly turbulent containing numerous vortices of different sizes and intensities. Each vortex in this complicated wake is the result of a periodic generation, and the periodicity sometimes induces serious vibration problems in steam generators and heat exchangers. The structure of the flow may be treated as a complex synthesized result of Karman vortex flow. This paper is the first report of a series of studies carried out form the above mentioned viewpoint, and presents the experimental results about a Karman vortex flow from two tubes at various spacings. The vortex formation region was visualized by means of the Schlieren method and was recorded by a 16 mm movie camera. The vortex shedding frequency was systematically studied. The frequency for two tubes is entirely different from that for a single tube. It was found that the size of the vortex formation domain has a dominant effect on the frequency.