Optimization design of shunt-hedging sand sampler based on numerical simulation and wind tunnel experiment

Abstract: Soil erosion is a serious environmental problem in arid and semi-arid regions, which has aroused wide concern among the public. Soil erosion is the process of denudation, sorting and transportation of farmland soil under the action of wind. Soil erosion can cause soil texture coarse, structure deterioration, decline of soil fertility and decrease of sustainable productivity, seriously restricting the sustainable development of agriculture. Sand sampler is one of necessary devices to research soil erosion, which is a key equipment in the observation of sand flow structure and laws of wind and sand movement. In addition, it is necessary to optimize the design of sand sampler so that we can obtain a large and accurate erosion data to improve the sand collection efficiency. However, the core component of the shunt hedging sand sampler is a sand separator. In addition, according to the combination of shunt hedging and multistage expansion, the wind speed reduction effect is more obvious, and the sand collection efficiency can be higher. In this paper, the FLUENT software and the micro wind tunnel are used as experimental platform to optimize the exhaust pipe diameter, exhaust pipe length, sand outlet diameter, and sand outlet contraction height of the separator of the shunt hedging sand sampler. Furthermore, the finite element model of the sand separator for the shunt hedging sand sampler was established. Meanwhile, according to the RNG turbulence model, the numerical simulation analysis is carried out for sand sampler. Besides, the DEM model is used to calculate the trajectory of sand particles entering the sand separator so that we can easily obtain the sand collection efficiency. Besides, through the low speed performance test and gas-solid separation efficiency test, the simulation results of the original sand separator and the optimized sand separator in FLUENT are verified based on indoor micro wind tunnel. Moreover, the numerical simulation and wind tunnel test results show that the exhaust pipe and sand outlet deceleration performance of the optimized sand separator has been improved obviously compared with the original sand separator. When the exhaust pipe diameter is 25 mm, the exhaust pipe length is 25 mm, the contraction height is 15 mm and the sand outlet distance is 75 mm, the impact of the gas flow on the automatic acquisition sensor is minimal under strong wind condition (13.8 m/s), the maximum wind speed of the exhaust pipe is 2.23 m/s, which is decreased by 7.47% compared with the original sand separator, the average wind speed of the exhaust pipe is 0.68 m/s, 8.11% lower than that of the original sand separator, the maximum wind speed of the sand outlet is 1.52 m/s, 35.59% lower than that of the original sand separator, and the average wind speed of the sand outlet is 0.23 m/s, 28.13% lower than that of the original sand separator. Meanwhile, the average separation efficiency can reach 99.82%. Therefore, compared with the original sand separator, the sand collection efficiency of the optimized sand sampler is improved by 1.56%.