Friction factor measurements in an equally spaced triangular array of circular tubes

Friction factor data for adiabatic cross flow of water in a staggered tube array were obtained over a Reynolds number range (based on hydraulic diameter and gap velocity) of about 10,000-250,000. The tubes were 12.7 mm (0.5 in.) outer diameter in a uniformly spaced triangular arrangement with a pitch-to-diameter ratio of 1.5. The friction factor was compared to several literature correlations and was found to be best matched by the Idelchik correlation. Other correlations were found to significantly vary from the test data. Based on the test data, a new correlation is proposed for this tube bundle geometry, which covers the entire Reynolds number range tested. [DOI: 10.1115/1.2903817] Keywords: friction factor, tube bundle, pressure drop, staggered array