Cross Flow Through in Closely Arranged Circular Cylinders : 1st Report, Surface Pressure Distribution and Flow Velocity Fluctuation in Circular Cylinders

• Published in: Transactions of the Japan Society of Mechanical Engineers Series B Vol. 62; no. 593; pp. 65 - 71
• Main Authors: NAKAI, Tetsushi, AYUKAWA, Kyozo, INOUE, Tsutomu
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society of Mechanical Engineers 25.01.1996
• Subjects: Circular Cylinder
• ISSN: 0387-5016; 1884-8346
• DOI: 10.1299/kikaib.62.65

Vibration and acoustic resonance of the tube banks of a boiler heat exchanger are some of the most important problem. These are due to interactions between flow and structure of the tube banks. When the tube pitch ratio is closely arranged, complicated flow in the tube banks will be expected. This study is concerned with the flow through tube banks with closely arranged tube pitch ratio. We measured the surface pressure of the tube in the tube banks and fluctuating flow at Res=1.5×104 to 4.8×104 using a model that has same pitch ratio as that of a boiler heat exchanger. We found that the flow through the tube banks took the form of the sheet with flow velocity providing minimum gap section, and that the second row were getting a maximum drag force in the tube banks. In this pitch ratio, the flow through the tube banks has three Strouhal numbers (Sts=0.47, 0.8 and 1.1). It seems that there are a vortex shedding frequency, fluctuating the separated shear layer normal to the flow direction, and fluctuation of the reattachment point.