An experimental investigation has been undertaken to determine the effect of oscillation of the heat transfer surface on turbulent film boiling heat transfer. A transient technique was used to calculate the heat flux from copper spheres of 1 in., 3/4 in., and 1/2 in. dia. In all tests, saturated liquid nitrogen at atmospheric pressure was used as the boiling fluid. The data obtained were found to be in good agreement with published theory at zero frequency. The range of frequencies studied was from zero to approximately 12 cps at peak-to-peak amplitudes of 2 in. and 1 in., i.e., at amplitude-to-diameter ratios of 1.00, 1.34, 2.00, 2.67, and 4.00. It was determined that oscillation of the heat transfer surface considerably increases the heat flux for a given temperature difference over that for natural convection film boiling. The results were correlated with a maximum deviation of +35, −17 percent. The correlation equation
showed that the Nusselt number was proportional to the vibrational Fronde number to the 2/3 power. Tests were conducted with spheres having a corroded surface, a glass-bead-peened surface and a Teflon-coated surface. The results show that the turbulent film boiling from an oscillating sphere is independent of the condition of the heat transfer surface over the range of frequencies and amplitudes tested.
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