Water Hammer Analysis, WH

Water Hammer Analysis, WH (Version 7.0)

The computer program WH, incorporating up-to-date computational procedures, may be used to analyze transient conditions in a pumping system, in a hydroelectric power plant, or pumped-storage project. The transient conditions may be caused by the opening or closing of valves, starting or stopping of pumps, and loading or unloading of turbines. The program may also be used to study the governing characteristics of a hydro power plant having a temporary droop or a PID (Woodward or ASEA) governor. The turbo-generator sets may be isolated or connected to a large electrical grid. Either English or SI units may be used.

The piping system may be a series or a branching system having up to 100 conduits (A program to analyze larger systems will be provided upon request at no additional cost.), 15 valves, 15 turbines, 15 pumps, five surge tanks, five one-way surge tanks, five air chambers, five cooling-water condensers, 30 air valves and 20 air cavities. Each conduit may be divided into as many as 1000 equal-length reaches. Input data may be entered manually or interactively using WHINPUT provided as part of the package. This input code allows access to the User's Manual and may be used to modify existing input data file s or create new ones. Input data is specified in a free-format and may have unlimited number of comment statements in the input data file. Several options are available for printing the program output. The computed transient conduit pressures and conditions for valves, turbines, pumps, surge tanks, condensers, and other appurtenances and devices may be stored in different files for post-processing and a computer code provided in the package may be used to plot results. Machine characteristics for 16 pumps (for four quadrants) and 11 Francis turbines (for full range of wicket gate openings) varying over a wide range of specific speed are included in the code which may be used if the User do not have such characteristics over the full range.

The method of characteristics is used to compute the transient conditions. Turbo-machines, control devices and other appurtenances are simulated as outlined in Applied Hydraulic Transients, third edition, by M. H. Chaudhry, Springer, New York, NY, 2013. Initial steady-state conditions may be computed by using WH or they may be specified as input. Oigawa Penstock Failure Windgap Pumping Plant: Comparison of Computed and Measured Transient Conditions.

The program has been verified by comparing the computed results with the field test data from a number of hydroelectric power plants and pumping systems.

Oigawa Penstock Failure (After Bonin, ASME)

Windgap Pumping Plant: Comparison of Computed and Measured Transient Conditions

Boundary Conditions

The following boundary conditions are included in the program:

  • Upstream reservoir
  • Downstream reservoir
  • Series junction
  • Branching junction
  • Dead end
  • Intermediate valve
  • Downstream valve;
  • Pump running at constant speed
  • Pump start-up
  • Pump failure
  • Francis turbine: load acceptance or rejection with turbine under governor or manual control, pressure-regulating valve may open or close synchronously with the wicket gates, turbo-generator isolated or connected to the grid
  • Pump turbine: load acceptance or rejection with turbine under manual control, change-over from generation to pumping mode and vice versa
  • Surge tank, simple or orifice, with several cross-sectional area changes
  • One-way surge tank
  • Air chamber
  • Condenser
  • Vacuum breaker
  • Air cavity
  • Pressure relief valve (Valve opens and closes depending upon the inside pressure).
  • Pressure-head variation with time
  • Discharge variation with time