Turbo-type machines

The present invention relates to a turbo-machine, and in particular to a turbo-type hydro machine being able to prevent flow instability from occurring within fluid (in particular, a water including freshwater and seawater), which flows in an inside thereof, by suppressing rotation of an impeller and stalls in rotation thereof due to re-circulation flow at an inlet of the impeller, irrespective of the types and fluid thereof. A turbo-type machine, comprising a casing storing an impeller within an inside thereof, and a plural number of grooves formed on an inner surface of the casing in a direction of pressure gradient of fluid, wherein the grooves are provided from 80 to 150 pieces around a periphery on the inner surface of the casing, and a total width of the grooves all around the inner surface of the casing is from 30% to 50% of a peripheral length on the inner surface of the casing. Also, the area on cross-section of the groove within an area where the blades exist is made larger than that of the groove outside where the blades exist, or openings are drilled on a bottom surface of the grooves, each penetrating through thickness of the casing, or the groove is made in a two-layer structure in the direction of pressure gradient of fluid. Or, a round portion is formed at a tip of the blade , or a fin , thereby suppressing the cavitations to generate, as well as obtaining stabilization of the characteristic curve thereof.