Experimental and Analytical Investigation of the Film-Conductance-Coefficient Boundary Condition for Thermal Shock of a Conical Shell

Abstract

This investigation considered the problem of submerging a hot conical shell into a stream of cold water flowing axially up the outer surface of the shell. The thermal boundary condition on the outer surface was formulated in terms of a film-conductance coefficient that was considered to be of constant value for any one instant of time. A 15-in-long by 8 in. in largest diameter by 0.21 in. in thickness cone constructed of 2017-T4 aluminum was used in the experimental portion of this investigation. By recording strains and temperatures on the inner surface of the shell, the variation in film-conductance coefficient with temperature on the outer surface of the shell was determined for water velocities of 1.37, 2.32, 3.20 fps. The assumption of a constant value of film-conductance coefficient over the outer surface of the shell is capable of yielding stresses accurate to ± 12 percent for the range of temperature to 100–300 F. The maximum stress resulting on the outer surface of the shell for the highest water velocity of 3.2 fps and a shell temperature of 300 F such that nucleate boiling was taking place on the surface resulted in a value of stress 25 percent of the maximum theoretical possible stress of EαΔT/(1 − ν).