The disclosure provides devices for cooling a turbine casing for a turbomachine and methods of using the same. The devices extend around an axis (X) and include air-distribution means configured to take in air and convey it to the casing. The air-distribution means include a first ramp and a second ramp extending circumferentially about the axis (X), each ramp having air ejection orifices intended to be directed towards the casing in order to cool it The devices further include adjustment means capable of adjusting the flow rate of air ejected at the level of the first ramp with respect to the flow rate of air ejected at the level of the second ramp.