Abstract: The pressure distribution of a static disk and relative rotational speed in the rotor-stator cavity were experimentally investigated.Results show that the static pressure increases with the radial accretion within 0.6 radius range,and the lowest value of pressure appears at the ejection hole and then increases sharply to the moderate stage along the radial direction.The pressure upon the static disk increases with the augmentation of flow rate,and decreases with the increase of rotational Reynolds number.A steady rotational core can be formed when the value of rotational Reynolds number is less than 2.6×10⁶ and the mass flow rate less than 4.50×10⁴.In addition,the variations of mass flow rate and rotational Reynolds number have little influences on the relative rotational speed.