Flow characteristics in a rotor-stator cavity with cooling air inlet at low radius

Experiments were conducted on a typical rotor-stator system where air entered through an annular slot at low radius and flowed out of the cavity axially through a rim seal between the rotor and the stator. For the seal in this rotor-stator system, the stationary shroud overlapped the rotating one. Pressure distributions at the stator surface and flow resistance coefficients of the rotor-stator cavity with a maximum gap of 67 mm were measured under different dimensionless mass flow rates from 1.32×10⁴ to 4.87×10⁴ with a large range of rotational Reynolds numbers from 0.418×10⁶ to 2.484×10⁶. The results show that pressure on the stator surface decreases with the increase of rotational Reynolds number when the dimensionless mass flow rate is below 1.3×10⁴; when the dimensionless mass flow rate is above 3.034×10⁴, the trend reverses. This is the so-called “pressure inversion effect”. However, dimensionless pressure does not show the same changes when rotational dynamic pressure is chosen as the denominator. The resistance coefficient of the rotor-stator cavity is determined by the dimensionless mass flow rate and rotational Reynolds number; for practical application, the resistance coefficient can also be estimated by the turbulent flow parameter in the range of turbulent parameter from 0.1 to 1.6.