Research On Fluid Dynamical Characteristics Of Multi-hole Orifice Plate In Hydraulic Cavitation

Firstly, this dissertation builds a model for structural design of standard orifice plate. It is necessary to define a formula for orifice arranging and a structural parameter by which could describe multi-hole orifice plate in detail. Based on this, this dissertation does the throttling experiment. It shows that the ratio of equivalent diameter is the dominant effect factor of the throttling phenomenon of multi-hole orifice plate by the result to the experiment.An effective equipment of hydrodynamic cavitation with multi-hole orifice plate as its element is built in order to find the basic rule which affected it. Throttling device plays a vital role in the cavitation equipment. As a type of throttling element which has a long history, orifice plate possesses many advantages. For instance, it is simple in structure, it also has reliable working function and a low production cost. Multi-hole orifice plate has the function of variable flow rate supplying through adjusting its area of throttling orifice. It is a new type throttling device because of its convenience and low cost.Cavitation phenomenon is a phase transition process from liquid to gas, cavitation bubbles while exercising and collapsing in the liquid can give out partial heat high pressure, pound of wave, high speed to shoot and flow an extreme physical condition etc. In order to prevent from damages the machine, cavitation should be avoided as far as possible in the water power machine, but this kind of characteristics also can make out the chemical reaction of the hard realization that cannot carry out in the general terms.From the data we can find that the resistance coefficient of every orifice plate had no variation in the turbulent state under different experimental conditions and the resistance coefficient of different orifice plate has close relation to the structure parameters. The structure parameters of the orifice plate can make a transparent efficient to its hydrodynamic. As an overall trend, if we increased the numbers of the holes and proportion circumference of the orifice plate, the flow in the pip would ascend while the resistance coefficient would become low. If we opened holes in the center then the resistance coefficient of the porous orifice plate would descend, especially when many holes were opened. The resistance coefficient of the orifice plates which have holes in the center would be lower than the ones which don't. We can get this conclusion from experimental results of the extreme condition and density of the holes that the arrangement of holes should avoid the extreme condition which can increase the resistance coefficient.