Heat transfer in an inlet region of a heat-generating rod bundle under conditions of longitudinal stream lining

The process is experimentally studied of heat exchange on the inlet region of the fuel rod bundle which is longitudinally flown around by the air. The bundle is made up of seven stainless steel tubes (outer diameter of 10 mm, wall thickness of 0.5 mm, length of 1200 mm) arranged inside a steel hexahedron. The experimental portion is positioned vertically and the tubes are heated throughout their entire length. The Re numbers have been changed from 18,000 to 73,000, the air temperature increment has not been over 20 deg. It has been revealed that the temperature of the outlying tubes on the external generatrix lines is always below than the temperature of the tubes on the internal generatrix lines. The average line of heat liberation throughout the entire length of the tubes is described accurate to (>=) 1,6% by the following formula: Nu = b(1 + c xexp/-K x(d)) Resup(0.8)Prsup(0.4), where b = 0.0150; c = 0.9413 K = 0.0424; x is the distance from the inlet; d is the diameter of the tube