Pressure forces downstream of dissipators
Hydrodynamics pressures caused by water jets downstream of spillway energy dissipators can be estimated in two ways: through hydraulic calculations or through measurements in hydraulic models. The methodology for estimating the hydrodynamics pressures downstream of a ski jump is based on the theory of free jet turbulence developed and tested by Prandtl for air–see F. Hartung and E. Hausler. The behavior is analogous to that of a jet of water coming from a nozzle and plunging into an unlimited water depth. The pressures obtained were higher than the real ones, therefore, in favor of safety, since the beneficial influence of the aeration in the dissipation of part of the energy in the aerial phase was neglected, given the complexity of the phenomenon. A flow parallel to a rocky surface as it occurs at the outlet of a dissipation basin will transmit to the rocky mass hydrodynamics pressures; the larger, the greater the flow velocities.