A cooling device for an annular casing of a turbomachine includes a collector housing having ejection openings in a radially inner part of the collector housing facing the annular casing and at least two cooling tubes extending circumferentially from the collector housing and having election openings in a radially inner part of the tubes facing the annular casing. The collector housing having an air passage formed by a radial groove extending radially from a radially inner end of the collector housing to a radially outer end of the collector housing and an axial groove extending from a first axial end to a second axial end of the collector housing.