1 - Alaska Energy Data Inventory

The orifice is normally omitted in this type of design to improve waterhammer reflections from the surge chamber. Details of the air chamber areshown on plate 36.D. Expected Turbine Characteristics - Turbine model test results wereavailable at HEDB for two turbines which approximated the hydraulicconditions at Crater Lake. These were the Long Lake model (SnettishamProject, Alaska) and the Dworshak model (Dworshak Dam, Idaho). TheDworshak model was selected at the time the air chamber was under study asbest suited for Crater Lake. (This selection has since been reversed sothat now the Long Lake model is preferred.)The Dworshak model stepped up to 600 r/min prototype with a 4.0 ftthroat diameter was found to fit the hydraulic conditions at Crater Lake.Plate B22 shows the prototype turbine characteristics (based on theDwprshak model) used for all transient studies for the air chamber surgetank plan. The turbine characteristic curve indicates the conditions forstability, rejection, and demand studies.An additional efficiency curve is shown on Plate B22 which plotsgenerator output vs. reservoir elevation at expected hydraulic lossconditions.Net heads and hydraulic capacity of the turbine were initially derivedfor the system described as Alternate Plan I in July 1982. Changes in netheads and hydraulic capacity were minimal since the expected hydrauliclosses ca 1 cu 1 ated for each ali nement are s imil ar; K = 1. 11 0 x 10- 4 forthe vented tank al inement and K = 1.093 x 10- 4 for- the air chamber tankalinement where HL = KQ2. ~ing the maximum discharge of 556 ft 3 / sresults in head losses of 34.3 ft and 33.8 ft for the vented tank and airchamber alinements respectively.This represents a 0.06 pct difference innet heads out of a total net head of 847 ft (rated net head), and th i sdifference is considered insignificant.Alternate Plan I consists of aB4-6