Boiling-burnout heat-transfer rates were measured with water flow¬ing vertically upward in electrically heated tubes. Flow stability in the experimental test section during burnout was affected by the amount of pressure drop across a throttling valve located upstream. As the restriction pressure drop across the valve was increased, the magnitude of the flow fluctuations in the test section decreased and the burnout heat flux increased until the pressure drop exceeded a critical value. For further increases in pressure drop, the flow was steady and the burnout flux was independent of the pressure drop across the throttling valve. The minimum restriction values required to stabilize the flow varied nearly linearly from 5 to 100 pounds per square inch with an increase in velocity from 0.5 to 40 feet per second;these values were independent of the pressure drop across the test section.
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