Hydraulic Model Studies of Y-Branch

Hydraulic model studies were made for the Y-branch steel penstock located in a vertical bend. The model tests were performed for various modes of pumping and generating operation. The prime objectives of the mode studies were to determine if the location of Y-branch in the bend is acceptable, to determine if head loss is sensitive to geometry of sickle plate, and to determine if pressure pulsations generated by the Y-branch and/or sickle plate would be significant to the structural design of the Y-branch. The model test indicated that head loss is not sensitive to the sickle plate size and any of the three sickle plates was acceptable from standpoint of head loss, and the decision for sickle plate geometry was based solely on structural consideration. The test also demonstrated that relocation of the Y-branch was not necessary in view of acceptable head losses and pressure fluctuations at the bend.