Control device for a turbine

A guide device (100) for a turbine (10), comprising:

• a vane bearing ring (110),
• a cover disk (150) which is arranged parallel to the vane bearing ring (110) and spaced apart therefrom in the axial direction (22) by spacer elements (160), and
• a plurality of adjustable guide vanes (120) which are each mounted rotatably and adjustably in the vane bearing ring (110), the adjustable guide vanes (120) being arranged between the cover disk (150) and the vane bearing ring (110),
• the adjustable guide vanes (120) being adjustable between a first guide vane position, in which the guide vanes are minimally open, and a second guide vane position (122), in which the guide vanes are maximally open,
• the respective guide vane position during operation of the guide device (100) being linked to a corresponding mass throughput through the guide device (100), the mass throughput being 100% in the second guide vane position,
• at least one of the vane bearing ring (110) and the cover disk (150) having a bevel (200, 200a, 200b) which, on a side (111, 151) of at least one of the vane bearing ring (110) and of the cover disk (150) facing the adjustable guide vanes, extends from an inner circumference (112, 152) of the vane bearing ring (110) and/or of the cover disk (152) in the radial direction (24) to a bevel outer radius (RA),
• the adjustable guide vanes (120) each having a guide vane trailing edge (123),
• the guide vane trailing edge (123) lying in the radial direction (24) in the region of the bevel (200, 200a, 200b) in the case of guide vane positions corresponding to a mass throughput range from a first mass throughput value to a second mass throughput value,
• the first mass throughput value being at most 35%.