Cavitacion Potencial De Vertederos Escalonados

Cavitation on stepped spillways has proven to be an undesirable condition. Bubble formation and vapor filled cavities is an important phenomenon that occurs in the flow over the stepped ramps. It is for this reason, that its eminent collapse has resulted significant damage to the main components of the spillway and appurtenant structures worldwide. Although stepped spillways are believed to be less prone to cavitation damage smooth spillways, designers still practice conservative in specifying stepped spillways in many places. Ideally question would be, ¿what are the characteristics of the flow that cause the formation of cavitation?

Auto-areation is a phenomenon that occurs in the flow of stepped ramps, and is one of the reasons for the construction of such structures. In this regard, the main objectives of enhancing slide structures are to increase the energy dissipation by internal friction flows and protect the bed overflows through the presence of air taken from the atmosphere.

Stepped spillways have long been thought to be less prone to cavitation damage than their more conventional smooth surfaced counterparts; however uncertainty in this notion has perceptuated conservative design practices. Skimming flow on a stepped channel forms a highly intense shear layer along the line connecting successive step tips. Flow structure within this shear layer supports formation of cavitation along secondary flow features with many similarities to other types of caviting shear flows, including plane shear layers.

The parameters to be adjusted for stepped spillways during the design phase, such as step height, flow regime, and the desired air flow rate will of course depend on the application proposed for the steps. In general the stepped design takes into account the higher energy dissipation efficiency of the stepped chutes, when compared with smooth chutes, because it implies in reduction of costs of the dissipation basin. The most difficult part of the interface simulation procedures is perhaps to obtain a realistic free surface flow solution. In a free surface flow, special numerical techniques are required to keep the position of the interface between the two phases. There are many free surface techniques available in the literature, which involve different levels of difficulties and several procedures to obtain a solution. In general, the numerical methods are under constant modifications, in order to improve their results and to avoid, as best as they can nonphysical representations. Because the computational tool itself is under constant improvement, increasing both, the storage and the calculation speed capacities, this situation of constant improvement of the numerical methods is understood as a “characteristic” of this methodology of study

The resulting empirically based formula estimated the cavitation index at the inception point as a function of the step height and specific discharge. Boes and Hager* reported a critical velocity for cavitation inception in the flow prior to air entrainment of approximately 20m/s. Based on the possibility that this velocity could be reached prior to the initiation of air entrainment for a range of slopes and step heights, they recommended limiting design specific discharges to 25m2.

Answering this question, we must take into account that have been used in laboratory experiments a suitable place for the pressure reduction, the main feature found through this study is based on the formation of cavitation to form staggered geometries are typical in stepped spillways in service in many of the structures in the world. Experiments in a closed conduit (nonaerated) revealed the strength and extent of the very intense shear layer is formed above the ends of passage. Advanced techniques for detection of cavitation characteristics together with high speed videography have additional

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