1 - Alaska Energy Data Inventory

CRITICAL AIR VOLUMES BASED ON SVEE EQUATIONSPowerCritical AirTunnel Penstock Volume BasedDiameter Diameter on Expecte~(ft) (ft) Losses (ft )11 6 18,76211 .5 6 21,89712 6 25,12412.2 6 26,600l3 6 32,845A water surface area of 3,500 ft2 was used for most calculations.any air chamber air volume, the tank will become less stable as the freewater surface area decreases. Calculations were done using a modified Sveeequation (eliminating the efficiency term), plotting Critical Water SurfaceArea vs. Critical Air Volume in the air chamber for various power tunnelsizes. The water surface area of 3,500 ft2 plotted in the stable regionfor all air chambers considered.AtF. Des i gn Approach Us i ng Computer Program "MSURGE II - Air chamberstability was also analyzed by using the computer program "MSURGE". Thisprogram was originally developed in the Southwestern Division HydroelectricDesign Branch in the 1960's, and was converted to Fortran by the HydrologicEngineering Center at Sacramento, California in 1965. The program utilizesthe arithmetic intergration procedures outlined in the text "HydraulicTrans i ents II by George R. Rich (ref. 14). The program was des i gned toanalyze load rejection, load acceptance, and stability. The program allowsfor variable turbine characteristics and variable tailwater elevations; italso allows for rapid analysis of such items as varying tank surface areaand volume, penstock and power tunnel sizes, etc. The program was expandedto include analysis of air chamber surge tanks in 1982District.in the AlaskaIn preliminary transient calculations tailwater elevations rangingbetween 11.0 and 12.5 ft were used while in the final design approach aconstant tailwater elevation of 11.4 was assumed. The constant tailwaterelevation simplifies calcuations with an inconsequential change in accuracy.B4-11