Turbo machinery

Turbo machinery comprising an impeller and a diffuser positioned on a downstream side of the impeller, a channel wall surface of the diffuser being composed of a pair of a shroud side diffuser plate and a hub side diffuser plate which surface each other and a channel width is formed so as to be increased downstream,

• characterized in that
• guide vanes in a circular arc shape lower in height than the channel width are installed in a line of a plurality of vanes on both channel walls of the shroud side diffuser plate and hub side diffuser plate of the diffuser, and a total of vane heights of the two guide vanes at an outlet of the diffuser is set so as to be within a range from 30 to 70% of the channel width at the outlet of the diffuser, and
• assuming an inclination angle of the channel wall surface of the shroud side diffuser plate in a radial direction as θs, a vane inlet angle of the guide vane installed on the wall surface of the shroud side diffuser plate in a peripheral direction at the inlet as βs, in, an inclination angle of the channel wall surface of the hub side diffuser plate in the radial direction as θh, and a vane inlet angle of the guide vane installed on the wall surface of the hub side diffuser plate in the peripheral direction at the inlet βh, in, respectively, said four angles set conform to a following formula (1),
• βs in−βh in=K(θs−θh)0 (1)
• and K of the formula (1) is set so as to conform to a relation of K<0.