In response to the significant friction and wear of gas bearings during the start-up and shutdown stages of supercritical carbon dioxide (S-CO2) power units,as well as the problems of low bearing capacity,low stiffness,small damping,and poor stability of gas bearings,a new type of S-CO2 lubricated hybrid tilting pad journal bearing structure was designed and improved.The S-CO2 lubricated bearing test rig was designed and built,and an experimental study was conducted on the dynamic characteristics of the new type of S-CO2 lubricated radial bearing under static pressure condition when the rotor of the test rig just started or ran at very low speed.The dynamic stiffness and damping of the bearing were obtained,and the influence of static pressure on the dynamic performance of the bearing was analyzed.The experimental results show that for the designed S-CO2 lubricated hybrid tilting pad journal bearing,the sufficient static pressure is generated between the bearing pad and journal during the start and stop stages to completely separate them,so the friction and wear of them is reduced during the start and stop stages.As the static pressure increases,overall stiffness and main damping of the bearing in X and Y directions increase,and the difference in the main stiffness coefficients between the two directions is not significant,while the cross stiffness and cross damping are close to 0.The research results provide a reference for further revealing the dynamic pressure characteristics of S-CO2 lubricated radial bearings.