Abstract
To predict natural frequencies of high-pressure centrifugal compressor impellers accurately, we measured the natural frequencies of an equivalent disc vibrating in a high-pressure gas environment. It is known that natural frequencies of pump impellers in water decrease compared with their natural frequencies in air due to the add mass effect. However, in our experiments in a high-pressure gas environment, the natural frequencies of the disc not only decreased but also increased compared with those operating under atmospheric condition. In order to clarify the effect of axial gap length and gaseous species, we set three ways of the axial gap length of our test apparatus and used four different gasses as the surrounding gas.
