The Change Law Of Gas Pressure In The Circulation Cavity And Ventilating Quantity Of Vent Under Swirl Condition

There are some advantages in level rotary inner energy dissipation with shaft inlet, for example, the energy dissipation rate is high> constructing is simple, assigning is flexibility, project fabrication cost is low, and so on. It has a greater theory meaning and popularize using value. Through the model test, under the swirl condition, this text researches on the change law of vent ventilating quantity of level rotary inner energy dissipation discharging hole, the change law of gas pressure in the circulation cavity and relation of every hydraulic characteristic.The result of study indicates that the change law of wind speed between freedom flow state and submerging flow state is different, the former' s state is exhausting, the latter' s state is ventilating; When the vent diameter is different, the wind speed and ventilating quantity are different, and the change with aperture is non-linear; The influence of the up and downstream water level on ventilating quantity is very obvious, when the flood peak on the weir is certain, with the increasing of the vent diameter, the ventilating amount increases and trends to constant, it presents the index law to reduce with increase of the downstream water level; The length of the air vent has certain influence on wind speed and ventilating amount; When geometry size of the vent is certain, the wind speed and ventilation amount of the ventonly depend on the change law of the gas pressure in the initial sections of circulation cavity.Freedom flow state and submerging flow state have different influence on cavity pressure. At submerging flow state, The change of ventilating quantity in the air vent has a tremendous influence to gas pressure in the cavity , with the increase of the vent diameter , the minus value of the gas pressure in the circulation cavity reduces quickly and tends to zero ; The gas pressure value in the circulation cavity is affected greatly by the change of downstream water level , with the reducing of downstream water level, the minus value of cavity pressure presents maximum and minimum .The mural pressure change with the up and downstream water level, different flow states have a tremendous influence to mural pressure , there is a certain balanced relation in gas pressure of circulation cavity and mural pressure, ventilating quantity, and this balanced relation is relative to up and downstream water level and swirl intensity .The research gets the subsidy of the national natural fund.