Analysis and experiment of the factors influencing the velocity of branch outlet in subsoiling shovel blade veined inner channel

Deep pine shovel is one of the protective tillage machines for the soda saline-alkali soil in Northeast China. Among them, the subsoiling shovel blade is one of the main working components in the deep pine shovel. The liquid lubrication and drag reduction have been explored in the self-developed deep pine shovel with the structure of leaf vein-like inner channel in the early stage for the saline and alkaline land improvement. This study aims to determine the effect of self-lubrication and drag reduction of deep pine shovel on the application of the modified liquid layer. The modified agent was also utilized for the layering of self-lubrication and drag reduction in the process of liquid flow rate within the leaf vein-like inner channel. The simulation analysis was adopted as the computational fluid dynamics with the physical test. A systematic investigation was then implemented to clarify the influence of structural parameters (inner channel aperture diameter, aperture spacing, and the number of apertures), and working parameters (inlet flow velocity of the main channel) on the liquid outlet velocity of the branch outlet. Firstly, the simulation model was established with the initial and boundary conditions, meshing and irrelevant verification. The single factor test was then carried out, where the structural and working parameters were taken as the test factors. The optimal level range was also achieved after optimization. The initial conditions were set for the simulation: an inner channel branch outlet hole diameter of 6 mm, a hole spacing of 90-110 mm, a number of holes of 4-6, and a main channel inlet flow rate of 5-7 m/s. After that, the Box-Behnken test was designed and then carried out, according to the single-factor simulation test. The target value was taken as the maximum liquid outflow velocity at the outlet of each branch. The structural and working parameters were optimized for the multi branch outlet pipes in the leaf vein shaped inner channel. The analysis of variance (ANOVA) of the test was used to establish the second-order regression equation between the influencing factors and the branch outlet flow rate. The optimal combination of simulation parameters was obtained to optimize and solve the equation. Finally, a field test was also conducted to verify the model. The results show that the better performance of the improved model was achieved for the further prediction analysis of the target mean flow rate. The ANOVA results showed that the influencing factors of the mean flow rate were ranked in the descending order of the main channel inlet flow rate, the number of branch exit holes in the inner channel, the spacing of branch exit holes in the inner channel. The second-order regression equation was optimally solved to take the maximum average flow velocity at the branch outlet as the target value. The optimal combination of parameters was achieved in the inner channel branch outlet hole spacing of 110 mm, the number of holes at the inner channel branch outlet of 4, the inlet flow velocity of the main channel of 7 m/s, and the hole diameter of the inner channel branch outlet of 6mm. Moreover, the average flow velocity at the branch outlet of the inner channel was 3.264 m/s under the optimal conditions. The physical test was then performed on the optimal combination of parameters for the leaf vein-like inner channel. The maximum flow velocity of 2.971 m/s was found in the inner channel branch outlet. There was the average error of 8.97% between the simulation and the physical test. Therefore, the reliability of numerical simulation was verified to examine the optimized design of the leaf-vein-like inner channel structure. The finding can provide the theoretical reference for the coupled deep-pine and chemical improvement using the leaf-vein-like inner channel with the multi-branch outlet pipe structure in soda saline soils.