Gas turbine engine swirled cooling air

A gas turbine engine having in flow series a compressor section, a combustor, and a turbine section, the gas turbine engine including:

• a turbine section rotor disk,
• a stationary wall forward of a front face of the rotor disk or rearward of a rear face of the rotor disk, the stationary wall defining a cavity between the stationary wall and the rotor disk, and having a plurality of air entry nozzles configured to deliver cooling air into the cavity at an inlet swirl angle, and
• a cooling air supply arrangement which accepts a flow of compressed cooling air bled from the compressor section and supplies the compressed cooling air to the air entry nozzles for delivery into the cavity;
• wherein the cooling air supply arrangement and the air entry nozzles are configured to vary the inlet swirl angle of the compressed cooling air delivered into the cavity through the nozzles between a first inlet swirl angle and a different second inlet swirl angle, and
• wherein a first portion of the air entry nozzles provides the first inlet swirl angle, and a second portion of the air entry nozzles provides the second inlet swirl angle, the cooling air supply arrangement having a switching system for switching the supplied compressed cooling air between the first and the second portions to vary the inlet swirl angle.