An experimental investigation was carried out to examine the effects of jet impinging positions on heat transfer from rib-roughened (square and semi-circular) channels with rotational speeds of up to 600 rpm. The rib height (e) was fixed at 1.5 mm and pitch-to-height ratio (p/e) kept at 6.67. The study covered jet Reynolds number in the range 5000-9000 based on jet hole diameter. Results were presented for rotational number, jet impinging positions, and roughened surfaces effects on local Nusselt numbers. Significant heat transfer enhancement was found for the present physical geometry and within the ranges of operating parameters considered in the study. Moreover, detailed heat transfer coefficients on target wall in a rotating square smooth channel using transient liquid crystal techniques for the rotational speeds of 30 and 60 rpm at Re-j = 7000 and 9000 were also examined. (C) 2004 Elsevier Ltd. All rights reserved.