Mixed Fluid Evenness Study Of Flow Field Of Wet Concrete Spraying Machine Nozzle

Wet concrete spraying machine is a widely-used engineering equipment in spray anchor support engineering field. However, during the process of construction, wet spraying machine is of high rate in rebound. For this core technology, this article claimed that the ingredient evenness and speed evenness of the mixed fluid (air, accelerator and concrete) are the crucial factors determining the concrete rebound rate. The gas-solid evenness of the flow field in the nozzle has been researched in this article using the numerical simulation combined with experimental verification. The specific work is as follows:First, building the physical model for the gas-solid mixed fluid in the wet spraying machine nozzle flow field; within CFD simulation software Fluent, the mathematical model of the gas-solid mixed fluid in the nozzle flow field has been built, which provides foundation for the numerical simulation of gas-solid mixed fluid.Second, applying the above physical geometry and mathematical models, this article simulates the speed, pressure and turbulence kinetic energy of the gas-solid mixed fluid in the wet spraying machine nozzle, and obtains the distribution law of velocity field, pressure field and phase volume fraction.Third, using the RNG k-ε turbulence model and making numerical simulation of the mixed fluid in the wet spraying machine nozzle with different structural parameters, to examine the impacts that the structural parameters exert on the evenness of gas-solid mixed fluid, and to get the relation between the gas-solid mixed fluid and wet spraying machine nozzle diameter ratio, half cone angle and import incident angle, and to attain the optimal combination of the three by using the evenness experimental design.Fourth, conducting numerical simulation of wet spraying machine nozzle flow field within different operation parameters, we get the relation that the pumpage of wet spraying machine and wind pressure of air compressor affect its mixing evenness, finding optimal air pressure of the wet spraying machine nozzle and analyzing the maximum injection capacity of the nozzle with the feature of the concrete analyzed in this article.Fifth, carrying out the injection experiments under different air pressure condition and pumpage of wet spraying machine nozzle. The results show that the rebound rate of the concrete can be decreased by increasing the ingredient evenness and speed speed evenness of the mixing fluid. The findings of this research can guide the design and use of wet spraying machine nozzle.