DRAFT TUBE OF HYDROELECTRIC POWER UNIT Russian patent published in 1999 - IPC

FIELD: hydroelectric and pumped storage plants. SUBSTANCE: draft tube has runner case, cone, and outlet diffuser. Arranged above the latter is additional bypass space communicating with outlet diffuser through intermediate tubes which are staggered as viewed from top and placed between additional bypass space and straight section of upper region of outlet diffuser. Exit part of outlet diffuser top is made in the form of curvilinear section. Downstream water is passed under the action of pressure drop through additional bypass space to upper region of outlet diffuser which reduces separation of upper water from draft tube top and decreases pressure fluctuations. EFFECT: improved reliability and service life of draft tube. 2 dwg