[en] Reflooding experiments have been performed to determine the transient void fraction in a heated vertical tube under oscillatory inlet flow conditions. Oscillations of various amplitudes and periods were superimposed on a constant feed rate and measurements were made of temperatures, void fraction, and mass carryover. For experiments with high coolant feed rates, large oscillations were observed in the void fraction, wall temperature, and heat transfer, indicating periodic changes in flow regime near the quench front. For experiments with low coolant feed rates, inlet flow conditions had much less effect on the measured parameters, especially at the upper elevations. The amount of liquid in the test section during these forced oscillation tests was lower than in the constant-injection rate tests due to increased droplet entrainment. This resulted in delayed quenching