Experiments on liquid droplet impingement erosion by high-speed spray

Abstract

In the present paper, liquid droplet impingement erosion is studied by using a high-speed spray. This experiment allows the evaluation of erosion rate of solid materials due to the impingement of liquid droplets having an order of tens of micrometer in diameter, which corresponds to those of actual conditions in nuclear power plants. The droplet properties are characterized by measuring the droplet velocity by particle image velocimetry, the diameter by shadowgraph and the number of impinging droplets in a unit area by sampling probe. The erosion rate of aluminum material by water droplets is tested by the high-speed spray in some combinations of the distances from the nozzle and droplet velocities. Although the experimental erosion rate in the far field of the nozzle is reproduced by the theoretical erosion model, the erosion rate in the near field does not. This suggests the damping effect of liquid film over the test specimen in the near field. The experimental result also indicates that the erosion rate increases in proportional to the power of 7.0 of droplet velocity in the maximum rate stage. The result indicates a certain degree of deviation from the previous experiment in literature, which may suggest the influence of the droplet diameter and the liquid film on the liquid droplet impingement erosion.