Study Of Liquid-solid Mixing Ratio And Its Stability In Suspension Water Jet System

Suspension water jet is a high-efficiency jet formation method,and the regulation and stability of the mixing ratio of water pellets in the jet is the primary condition that restricts the normal application of the suspension mixed jet.As the formation of suspension jet requires two processes,primary mixing and secondary mixing,multiple damping string and parallel measures are required for precise regulation of the flow,and the pressure-flow characteristics of the above regulation process as well as the outflow characteristics under different concentration conditions need to be studied in depth.Based on the above,the following research work was carried out in the thesis.The theoretical study of the small hole outflow characteristics was carried out.The small-hole flow coefficients for different damped-hole conditions are calculated according to the small-hole flow theory,and the corresponding flow equations are given;the equations for the mixing ratio of the pre-mixed abrasive jet outflow are derived and verified experimentally.The outflow characteristics of the primary mixing fluidization chamber in the jet system were investigated.Based on the construction of a simple fluidization chamber test system,the outflow mixing ratio and its stability were studied under different diameters of damping holes,different diameters of filled pellets and different test pressure differential conditions.When the diameter of the damping hole is determined,the mixing ratio of the discharge flow decreases with the increase of the pellet diameter.A combination of weighing and measurement methods was used to evaluate the stability of the outflow mixing jets and the corresponding outflow mixing ratios at steady and small differential pressures,and the resulting flow mixing jets and their mixing ratios were continuous and stable.Relevant on-stage and off-stage field experiments were conducted.The mixing ratios of the primary mixing circuit on the pre-mixing surface modification testbed were found to range from 44.29%to 49.88%for a specific damping ratio.The secondary mixing circuit was replaced with three different sets of damping ratios to obtain the corresponding mixing ratios:d₂=1.8 mm,d₄=1.8 mm in the range of5.547%～6.0229%;d₂=1.5 mm,d₄=1.5 mm in the range of 6.521%～7.18%;d₂=1.2 mm,d₄=1.2 mm in the range of 11.74%～12.37%.Through the mixing ratio calculation formula,it can be known that when the damping ratio is determined,the decisive effect on the mixing ratio is the pressure difference ratioΔp₂/Δp₁ at the front and rear ends of the two branch valve blocks.Therefore,when the damping ratio of d₂=1.2 mm and d₄=1.2 mm is selected,the variation range of the corresponding pressure difference ratio is 1.7488～2.5 when the input pressure difference is 5 MPa,10 MPa,18 MPa and 28 MPa respectively.According to the mixing ratio calculation formula,the distribution range of the outlet mixing ratio is 11%～14.38%,which is basically consistent with the mixing ratio range of 11.74%～12.37%.This law is also applicable to other damping ratio conditions.Based on the above,it can be concluded that the mixing ratio of the new premixed abrasive water jet is stable and continuous.