Determination method for incipient cavitation number of flattop pore plate

Abstract

The invention relates to a determination method for an incipient cavitation number of a flattop pore plate. According to the method, factors influencing the incipient cavitation number are determined,wherein the factors include a pipe water flow Reynolds number, a specific value of a pore plate diameter to a flood discharging tunnel diameter and a specific value of pore plate thickness to the flood discharging tunnel diameter; a numerical simulation model of water flow passing through the flattop pore plate is established based on an RNG k-epsilon model; a calculation method of the incipientcavitation number is determined based on the RNG k-epsilon model; and the numerical simulation result is analyzed and fitted, and an empirical expression between the incipient cavitation number and the factors influencing the incipient cavitation number is determined. The method has the advantages that a quantitative relation between the incipient cavitation number and the pipe water flow Reynoldsnumber, the specific value of the pore plate diameter to the flood discharging tunnel diameter and the specific value of the pore plate thickness to the flood discharging tunnel diameter is obtained,so that the method is suitable for direct application to a real project.

Description

technical field [0001] The invention relates to the technical field of water conservancy engineering, in particular to a method for determining the primary cavitation number of a flat-head orifice plate. Background technique [0002] The orifice plate has an important application in the flood discharge of high dams. The flow state of the water flow through the flat head orifice plate is as follows: figure 1 shown. Due to the special shape of the orifice plate, when the water flow passes through the orifice plate, there will be sudden contraction and expansion, forming a rolling area of ​​the water flow in the front and back of the orifice plate, and strong shear and strong friction will be generated inside the water flow. Neighbors will be disinfected. The orifice plate has the characteristics of simple layout, economy, high energy dissipation efficiency, and small cavitation damage, etc., and has an important application prospect in future hydropower energy dissipation. ...

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Problems solved by technology

[0004] "Journal of hydraulic engineering" No. 8, 2001, the article titled "Hydrauliccharacteristics of multistage orifice tunnels" pointed out that the primary cavitation number and energy loss coefficient of the orifice plate are mainly closely related to the aperture ratio β (β=d / D, Where d is the diameter of the orifice, D is the diameter of the spillway, d and D see figure 1 ), the larger the β, the smaller the primary cavitation number of the orifice plate, and the stronger the ability of the orifice plate to resist cavitation damage, but the energy loss coefficient of the orifice plate is also smaller, and the energy dissipation effect will be worse

Most of the existing studies on the primary cavitation number and energy loss coefficient of the orifice plate remain at the qualitative analysis level. Although the research conclusions have guiding value for practical engineering, the relationship between the primary cavitation number and related body shape elements and hydraulic elements has not been obtained. The quantitative relationship between them is not suitable for direct application in actual engineering

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