Numerical simulation and organization method for discharge coefficient of CFN for high pressure hydrogen gas

In this study, numerical simulations are conducted to establish a method for organizing the discharge coefficient of high-pressure hydrogen. Similar to the experiment, the numerical simulation also confirmed that the discharge coefficient decreases with increasing Reynolds number at high pressure (40, 70, and 100 MPa). The experimental and numerical simulation results are in close agreement with each other, and thus the validity of the results can be confirmed. By using the value of the critical flow function at high pressure for the calculation of the theoretical mass flow rate, it is clarified that the discharge coefficient is an increasing function of Reynolds number. However, since the values of the discharge coefficient are not consistent with the ISO proposed equation, and the value of the discharge coefficient exceeds 1.0. Therefore, there is room for the improvement in the derivation method of the theoretical mass flow rate.