Experimental and simulation-based investigations on throttle’s head loss coefficients of a surge tank

Abstract

For the different types of throttled surge tanks used in hydropower systems, it is important to comprehensively know the throttle's head loss characteristics for exact surge analysis and transient control. Herein, a general and complete experimental setup was designed to steadily reproduce the 12 typical flow regimes occurring at the surge tank and thus conduct comprehensive experimental research on throttle head loss coefficients. Furthermore, an extended mathematical model for the surge tank was derived by inputting experimental data on the throttle's head loss coefficients to surge analysis. Through experimental research, the throttle's head loss coefficients were determined by fitting formulae relative to the different flow regimes and discharge ratios; via a detailed case analysis, the differences in the head loss characteristics for different throttle types were accurately determined. It was demonstrated that the throttle's head loss coefficient varies with discharge ratio under different flow regimes and found that the experimentally obtained flow coefficients for different throttle types are more accurate and clearly reveal the difference of throttles’ head loss characteristics. The extended mathematical model for the throttled surge tank can provide more accurate simulation results and guidance for its engineering design and layout.