Copyright © 2005 by ASME 1 Proceedings of HT2005 2005 ASME Summer Heat Transfer Conference July 17-22, 2005, San Francisco, California, USA HT2005-72791 COMPUTATION OF VELOCITY PROFILES AND PRESSURE COEFFICIENTS FOR A LAMINAR FLOW OF AIR OVER STAGGERED ARRAY OF TUBES Ramin Rahmani Faculty of Science and Technology Anglia Polytechnic University Victoria Road South, Chelmsford, CM1 1LL, UK Tel: +44 (1245) 493131 3395 Fax: +44 (1245) 493136 Email: r.rahmani@apu.ac.uk Ahad Ramezanpour Faculty of Science and Technology Anglia Polytechnic University Victoria Road South, Chelmsford, CM1 1LL, UK Tel: +44 (1245) 493131 3395 Fax: +44 (1245) 493136 Email: a.ramezanpour@apu.ac.uk Iraj Mirzaee Mechanical Engineering Dept. Faculty of Engineering, Urmia University 1.5 km Serow Road, Urmia, Iran, P.O.Box 165 Tel: + 98 (441) 2778984 Fax: +98 (441) 2777022 Email: i.mirzaee@mail.urmia.ac.ir Hassan Shirvani Faculty of Science and Technology Anglia Polytechnic University Victoria Road South, Chelmsford, CM1 1LL, UK Tel: +44 (1245) 493131 3375 Fax: +44 (1245) 493136 Email: h.shirvani@apu.ac.uk ABSTRACT In this study a two dimensional, steady state and incompressible laminar flow for staggered tube arrays in crossflow is investigated numerically. A finite-volume method is used to discretize and solve the governing Navier-Stokes equations for the geometries expressed by a boundary-fitted coordinate system. Solutions for Reynolds numbers of 100, 300, and 500 are obtained for a tube bundle with 10 longitudinal rows. Local velocity profiles on top of each tube and corresponding pressure coefficient are presented at nominal pitch-to-diameter ratios of 1.33, 1.60, and 2.00 for ES, ET, and RS arrangements. Differences in location of separation points are compared for three different arrangements. The predicted results on flow field for pressure coefficient showed a good agreement with available experimental measurements. Keywords: crossflow; staggered; tube bank; velocity profile; pressure coefficient INTRODUCTION There are many industrial heat exchanger designs involving a bank of tubes in a fluid crossflow. Significant empirical and experimental efforts have been done to understand the fluid flow behavior and heat transfer in this complex phenomenon (e.g. [1]). In order to choose the optimal heat exchanger among the different design options, a designer needs to have a large database available from actual measurements, theoretical simulation or numerical model. Although, the most reliable performance comes from the experiment, however, it is expensive and time consuming. The simulation approach is a mathematical model which normally gives a good insight in understanding the flow and heat transfer for very limited cases. Unfortunately, the difficulties arise in the nonlinearity at the Navier-Stokes equations and for complex heat exchanger geometry. Consequently, due to the rapid development in the computational side, the numerical solution becomes a good alternative during design of heat exchangers. Two types of tube arrays can be considered: in-line tube arrays and staggered tube arrays. The staggered tube arrays can also be used in several possible tube arrangements (shown in Fig. 1): an equilateral triangle (ET), a rotated square (RS) and equal spacing (ES) arrangements. In general, the heat transfer in a staggered array of tubes is found to be higher than that in- lined array of tubes. However, the pressure drop in a staggered array arrangement is also higher. Launder and Massey [2] presented detailed results using a finite difference method for RS tube arrangement. They obtained the results with nominal pitch-to-diameter ratios of 1.25, and 2.12 at Reynolds numbers between 2 and 1,000. Antonopoulos [3] studied a fully developed and developing crossflow by using a finite- difference method. He presented results in RS arrangement with pitch-to-diameter ratios of 1.25, and 2.135 at Reynolds numbers between 5 and 200 for Prandtl numbers of 1, 10, and 30. Chen, et al. [4] applied a finite-element method to compute the flow and heat transfer in an ET arrangement with nominal