This paper shows the LH2 propellant management of the precooled turbo jet engine "PCTJ". On the fuel supply system of the core-engine, liquid hydrogen is vaporized in the evaporator in the combustor and supplied to the combustor. The hydrogen changes its density drastically with accompanying its phase (liquid, gaseous and two-phase flow) depending on time and space. Hence, it is very difficult to control the mass flow rate especially at the start-up transient condition. In this study, the transient variation of the hydrogen flow rate is simulated by using the heat transfer model which includes several boiling styles. The result has a quantitative difference from the experimental data though the trend is similar. Thus, a test on the boiling heat transfer of liquid hydrogen is planed to get the heat transfer and pressure loss data for improvement of the simulation accuracy. The heat transfer depends on the boiling style and void fraction. In advance of the hydrogen test, preliminary test using deionized water and air was conducted to construct the method of void fraction measurement using the capacitance meter and high-speed camera.