AFT Impulse provides a practical tool for the piping systems engineer to address the complex subject of liquid piping systems waterhammer and surge transient events. AFT Impulse incorporates an integral steady-state solver to calculate the initial conditions and seamlessly transfer these to the transient solver.
Based on the same, proven solver in AFT Fathom, steady-state solutions are determined using a modified Newton-Raphson matrix interation. AFT Impulse’s transient flow solution engine is based on the Method of Characteristics, which utilizes a prescribed relationship between time step and distance step. This permits a direct solution of each time step, making AFT Impulse highly efficient.
AFT Impulse lets you specify transients both on a time and event basis. For example, initiate a pump startup based on the pressure at a selected location in the system or a valve closure upon the flow direction at selected location. This powerful capability greatly expands the type of transients that may be modeled including a variety of control logic functions.
Pump modeling can be as simple as a fixed flow or as sophisticated as including four quadrant effects modeling the various possible combinations of forward and reverse flow and rotation. Start and trip modeling can use specified speed vs. time or account for pump/driver inertia and driver torque vs. speed. Pump models may include integral check valves and reverse rotation brakes. more
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