Fundamentally, a turbine is a type of rotating equipment designed to remove energy from a fluid. For a given flow rate, turbines remove a specific amount of the fluid’s energy head. HAMMER CONNECT provides a single but very powerful turbine representation:

• Turbine between 2 Pipes—A turbine that undergoes electrical load rejection at time zero, requiring it to be shut down rapidly. The four-quadrant characteristics of generic units with certain specific speeds are built into HAMMER CONNECT. The turbine element allows nonlinear closure of the wicket gates and is equipped with a spherical valve that can be closed after a time lag. It has the following parameters:
• Time (Delay until Valve Operates) is a period of time that must elapse before the spherical valve of the turbine activates.
• Time for Valve to Operate is the time required to operate the spherical valve. By default, it is set equal to one time step.
• Pattern (Gate Opening) describes the percentage of wicket gate opening with time.
• Operating Case allows you to choose among the four possible cases: instantaneous load rejection, load rejection (requires torque/load vs time table), load acceptance and load variation.
• Diameter (Spherical Valve) is the diameter of the spherical valve.
• Efficiency represents the efficiency of the turbine as a percentage. This is typically shown on the curves provided by the manufacturer. A typical range is 85 to 95%, but values outside this range are possible.
• Moment of Inertia The moment of inertia must account for the turbine, generator, and entrained water.
• Speed (Rotational) denotes the rotation of the turbine blades per unit time, typically as rotations per minute or rpm. The power generated by the turbine depends on it.
• Specific Speed enables you to select from four-quadrant characteristic curves to represent typical turbines for three common types: 30, 45, or 60 (U.S. customary units) and 115, 170, or 230 (SI metric units).

The equation to estimate specific speed for a turbine is as follows:

In US units n is in rpm, P is in hp, and H is in ft.In SI units n is in rpm, P is in kW, and H is in m.

• Turbine Curve For a transient run, HAMMER uses a 4-quadrant curve based on Specific Speed, Rated Head, and rated Flow. This is only used for steady state computations.
• Flow (Rated) denotes the flow for which the turbine is rated.
• Head (Rated) denotes the head for which the turbine is rated.
• Electrical Torque Curve defines the time vs torque response for the turbine. Only applies to the Load Rejection operating case.