Numerical Simulation Of Pumping And Suction Of Concrete Pump Truck And Research On Optimization Of The Stirring Blade

Concrete pumping machinery has the advantages of high suction efficiency and continuous operation,and has been widely used in various large and small concrete construction projects.The pumping and suction unit is the core part of the concrete pump truck.It controls the reciprocating motion of the concrete piston under the hydraulic power to complete the suction and push work,and continuously transport the fresh concrete in the concrete pump hopper to the on-site pouring site through the output pipeline.The mixing blade is located in the hopper of the pumping suction unit.The continuous stirring ensures the flow performance of the fresh concrete in the hopper,promotes the suction of the pumping suction unit,prevents the fresh concrete from gathering and rapidly solidifies,and prevents a large amount of coarse aggregate.Sedimentation at the bottom of the hopper occurs to block the pipe.Optimizing the structure of the stirring blade can improve the suction performance of the pumping suction unit and reduce the stirring energy consumption in the pumping suction process.At present,numerical simulation has become an efficient and highly recognized method to study the flow of fresh concrete,and many scholars choose discrete element(DEM)for simulation.However,the numerical simulation research on pumping and suction only studies the pumping flow of fresh concrete in the pipeline,and does not consider the suction process.Numerical simulation study of specific suction work.Therefore,it is urgent to realize the numerical simulation method of the pumping and suction process of fresh concrete,which can be combined with the experimental research to provide a reference for the research of pumping and suction.In this paper,the discrete element method is used to numerically simulate the pumping and suction process of fresh concrete in the pumping suction unit of the pump truck,and the influence of the stirring blade in the pumping suction unit on the pumping suction is discussed.For optimization,the stirring energy consumption is reduced without reducing the suction efficiency.The main research contents are as follows:(1)In this paper,the physical parameters of the machine-made stone were measured,the numerical model of the fresh concrete was established based on the discrete element method,and the rheological experiment was carried out,and the experimental results of the slump and L box test were compared with the numerical simulation results.,calibrate the unknown parameters,check the DEM model of fresh concrete,prove the reliability of the DEM model of fresh concrete and the feasibility of simulating the flow behavior and rheological properties of fresh concrete.(2)In this paper,a self-defined method is used to construct the suction model of the suction process,and the numerical simulation of the pumping and suction process of fresh concrete is realized,which provides a reference for the study of the numerical simulation of pumping and suction.Furthermore,the material flow field during the pumping and suction process under typical working conditions was observed,and the particle flow velocity at different positions was counted to study the material particle flow trajectory.It was found that the particle flow caused by the stirring blade was the most stable and lasting,with the strongest controllability,and had a greater impact on the pumping and suction process.(3)In this paper,by means of the discrete element numerical simulation of the pumping and suction process,the influence of the working speed of the stirring blade,the installation angle,and the edge distance of the opening on the pumping and discharging suction efficiency and the stirring resistance moment of the stirring blade are explored.It is found that the higher the rotational speed,the greater the suction efficiency,and the installation angle and the opening margin have little effect on the suction efficiency.(4)This paper proposes an optimization scheme for the structure of the stirring blade.The numerical simulation results show that the suction efficiency is improved by 1.22%,and the stirring resistance torque of the stirring blade is reduced by 11.8%.Further,a material suction test bench was built and a series of experiments were carried out.The experimental results show that by optimizing the structure of the stirring blade,the suction efficiency is increased by 1.47%,and the stirring resistance moment of the stirring blade is reduced by14.6%.Comparing the numerical simulation and experimental results,it proves the feasibility and accuracy of DEM numerical simulation of pumping and suction.It was found that by optimizing the structure of the stirring blade,the expected goal of reducing the stirring energy consumption of the stirring blade without reducing the suction efficiency was achieved.