Short impeller for a turbomachine

A subsea multiphase fluid pressure increasing machine, comprising:

• an elongated member rotatable about a longitudinal axis;
• a motor system mechanically engaged to the elongated member so as to rotate the elongated member about the longitudinal axis in a rotation direction;
• and
• a plurality of impellers coupled to the elongated member, each impeller comprising a plurality of individual blades, each blade comprising a leading edge, a trailing edge, a suction side, a high pressure side, a first side engaged with the elongated member, a second side, a chord length, and a chord line defined by a line between the leading and trailing edges and each impeller being mounted such that a chord angle of each blade defined by an angle between the chord line and the rotation direction is less than or equal to a stall angle;
• wherein at least some impellers of the plurality of impellers having at least one unobstructed opening extending through each individual blade at a location between the leading edge and the trailing edge, wherein the at least one unobstructed opening comprises a slot on the suction side, the slot extending from the first side to the second side and defined by a bottom surface, a top surface, and a middle surface extending from the bottom surface to the top surface, the slot disposed between a first portion of the suction side and a second portion of the suction side, the first portion of the suction side extending from the trailing edge to the bottom surface, wherein the first side is partially defined by a first end of the slot and the second side of the blade is partially defined by a second end of the slot;
• wherein the at least one unobstructed opening further comprises at least one orifice and each orifice of the at least one orifice extends from the high pressure side to the bottom surface;
• and
• wherein the machine is configured for subsea deployment and does not experience surge induced by boundary layer separation with any positive multiphase fluid flows.

A method of imparting force on a multiphase fluid, comprising:

• rotating an elongated member about a longitudinal axis in a rotation direction, the elongated member having fixedly mounted thereto a plurality of impellers;
• providing each impeller with a plurality of individual blades, each blade having a leading edge, a trailing edge, a suction side, a high pressure side, a first side engaged with the elongated member, a second side, a chord length, and a chord line defined by a line between the leading and trailing edges, each impeller being mounted such that a chord angle of each blade defined by an angle between the chord line and the rotation direction is less than or equal to a stall angle at which a maximum force is exerted on the multiphase fluid in a direction primarily parallel to the longitudinal axis;
• and
• arranging at least one unobstructed opening through each individual blade at a location between the leading edge and the trailing edge, wherein the at least one unobstructed opening comprises a slot on the suction side and at least one orifice, the slot extending from the first side to the second side and defined by a bottom surface, a top surface, and a middle surface extending from the bottom surface to the top surface, the slot disposed between a first portion of the suction side and a second portion of the suction side, the first portion of the suction side extending from the trailing edge to the bottom surface, wherein the first side is partially defined by a first end of the slot and the second side of the blade is partially defined by a second end of the slot, and wherein each orifice of the at least one orifice extends from the high pressure side to the bottom surface;
• wherein the impellers are configured for subsea deployment and do not experience surge induced by boundary layer separation with any positive multiphase fluid flows.