Supercritical CO2 (S-CO2) has the potential to be used as the working fluid in a power cycle since S-CO2 shows a density value high as its liquid phase while the viscosity value remains closer to its gaseous phase. Thus, it requires much less work to compress due to its low compressibility as well as relatively small flow resistance. However, the S-CO2 leakage flow from turbo-machinery via seal becomes one of the important issues since not only it influences the cycle efficiency due to parasitic loss but also it is important for evaluating the system safety under various operating conditions.
In the previous turbo expo paper, the effect of the tooth length on the critical flow and comparing the results to the existing two phase system analysis code calculation were presented. In this paper, the gap effect, which is simulated by changing the diameter of a orifice and the number of tooth effect in a labyrinth seal geometry nozzle are presented by using the same experimental facility described in the previous paper. In addition, this paper includes the experimental results under various conditions including not only single phase flow such as supercritical, and gaseous state only but also two phase flow condition.