An experimental investigation on the gas ingestion phenomenon was performed on the rig of 1.5 stage turbine with different rotating velocities and seal mass flow rates. The experimental measurements include time-average and unsteady pressure field measurements and carbon dioxide volume fraction technique. These data were used to find out the influence of the interaction between rotor blades and stator blades on the phenomenon of gas ingestion and investigate the details during the process of the main gas into the cavity. The study suggests that

some part of the pressure on the annulus out of the seal in higher than the pressure inside seal rim due to the circumferential variation following the vane pitch. And this part decreases as seal mass flow rate increases. An unsteady blade-periodic component is found in this experiment

which is also a key to ingestion. The minimum necessary value of seal mass flow rate is obtained by carbon dioxide volume fraction technique. And the fact that the path of the main gas ingestion into the disk cavity is arranged along the stator when seal mass flow rate is not enough can also be inferred.