Ventilated end turns for rotor windings of a dynamoelectric machine

In combination with a rotor for a gas cooled dynamoelectric machine, said rotor inlcuding a rotor body defining at least a pair of axial winding slots, one of the at least a pair of winding slots respectively circumferentially disposed at the periphery of the rotor body on respective sides of a pole portion of the rotor body and the rotor body further defining at least one gas discharge flue extending from a pole face of the rotor body to the periphery of the rotor body, the pole face disposed on an axial end of the rotor body, said rotor further including a spindle coupled to the axial end of the rotor body, said spindle for rotatably mounting said rotor, a rotor winding cooling system comprising:

• a plurality of axially extending electrical conductors disposed in the winding slots, at least a portion of the axial conductors extending beyond said rotor body to form an axial end turn conductor, at least one of said plurality of axial conductors disposed on each side, respectively, of said pole face, each axial conductor including a first bar of metal, said first bar having a first substantially longitudinal groove for forming a passageway for receiving a first portion of gas, said passageway defined in part by insulation to be interposed between axial conductors within said winding slot for respectively electrically insulating each axial conductor within said winding slot from other axial conductors within said winding slot, respectively, said passageway including first port means for introducing gas into the passageway and second port means for withdrawing gas from the passageway
• a plurality of circumferential end turn electrical conductors for respectively electrically connecting the respective at least one of said plurality of axial conductors on one side of the pole face with the respective at least one of said plurality of axial conductors on the other side of the pole face, respectively, for forming a respective current carrying loop, each circumferential end turn conductor including a second bar of metal having a second substantially longitudinal groove for forming a passage for receiving a second portion of gas, said passage defined in part by a member coupled to the second bar, said plurality of circumferential end turn conductors arcuately spanning said pole portion and stacked with electrical insulation interposed between adjacent circumferential end turn conductors, respectively, said passage including third port means for introducing gas into the passage and fourth port means for withdrawing gas from the passage;
• a retaining ring affixed to said rotor body and circumferentially surrounding said axial and circumferential end turn conductors for maintaining said axial and circumferential end turn conductors in fixed spatial relationship against centrifugal and circumferential forces;
• a centering ring affixed to said retaining ring and axially spaced from said rotor body to substantially enclose an end turn region about said axial and circumferential end turn conductors, said end turn region defined by the axial end of said rotor body, the radial inner surface of said retaining ring, the radial outer surface of the spindle and the axial surface of said centering ring opposing the axial end of said rotor body, said centering ring further defining an annular space between the radially inward portion of said centering ring and the radially outer portion of the spindle, said annular space for introducing flow of the first and second portion of gas into said end turn region;
• and
• blocking means disposed within said end turn region for preventing gas flow communication between a portion of said end turn region and the balance of said end turn region for forming a low pressure area in said portion of said end turn region, said low pressure area arcuately spanning a predetermined portion of said pole face and a predetermined arcuate portion of said plurality of circumferential end turn conductors, said low pressure area further axially spanning said circumferential end turn conductors, and said low pressure area in gas flow communication with said gas discharge flue, wherein centrifugal pumping action during rotation of said rotor encourages gas to flow through said discharge flue to the periphery of said rotor, thereby reducing the pressure within the low pressure area of said end turn region with respect to the pressure in the balance of said end turn region;
• wherein the first and third port means are in gas flow communication with the balance of said end turn region, the second port means is in gas flow communication with the periphery of said rotor and the fourth port means is in gas flow communication with the low pressure area of said end turn region.