Cavitation Damage in Flowing Liquid Sodium Using Venturi Test Section

概要

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The present paper describes the damage behavior caused by cavitation in flowing liquid sodium using venturi test section. The venturi test section was made from 316 SS with an inner diameter of 6.5 mm and a length of 20 mm. The experiment was conducted with pressure of argon cover gas in the expansion tank ranging from 105-110 kPa. The liquid sodium temperature was kept at 200°C and the sodium flow rate was 27-28 L/min, which corresponded to developed cavitation condition with the cavitation coefficient of 0.59-0.51. This condition was kept for 600 hours during the experiment. The results showed that cavitation bubbles collapse created damage on the inner surface of the venturi test section in the form of pits due to eroded surfaces. Under SEM, most of the pits on the inner surface of the venturi test section were in the sizes of around 25 µm. Some pits with sizes larger than 25 µm were also observed with the largest diameter around 110 µm which indicated intense collapse of cavitation bubbles. Observation on the inner surface of the test section also indicated some micro cracks, which might be caused by the cyclic process of the formation and collapse of the bubbles during cavitation process.