Abstract
In response to the problems of small working width and low operating efficiency of existing hydraulic scouring lotus root harvesters, a wide-width hydraulic scouring system was designed based on a wide-width self-propelled lotus root harvester. The main parameters of the key components were determined through theoretical analysis of the water flow energy of the hydraulic scouring system pipelines. An experimental study was also carried out on the main factors affecting the working performance of this hydraulic scouring system. Through hydrodynamic simulation tests, the effect of nozzle type and constriction section structure on the turbulence intensity at the nozzle outlet and the pressure loss per unit mass of fluid between the nozzle inlet and outlet sections were compared and analysed. The test yielded conical-cylindrical nozzle geometry parameters for nozzle inlet diameter of 40 mm, shrinkage angle of 30°, nozzle outlet straight section length of 20 mm, nozzle outlet diameter of 16 mm, the nozzle had better flushing performance. Single-factor tests were carried out with nozzle outlet pressure, scouring angle and nozzle height from the mud surface as influencing factors. Based on the optimum effective scour depth, a three-factor, three-level Box–Behnken central combination design test was completed. The primary and secondary factors affecting the effective scouring depth were obtained in the following order: nozzle height from the mud surface, nozzle outlet pressure, and scouring angle. Finally, the performance test of the hydraulic scouring system was completed. Results showed that when the nozzle outlet pressure of 0.30 MPa, the scouring angle of 60° and the nozzle height from the mud surface of 0 mm, the effective scouring depth was 395 mm, the lotus root floating rate was 90% and the damage rate was 5%, which meet the requirements of lotus root harvesting operations.
Highlights
Lotus root, a popular aquatic vegetable, is being grown in China year after year
The F-values in Table 11 show that the influence of each factor on the nozzle scouring depth are significant in descending order of X3, X1, X2, X32, X1X3, which means that the interaction of nozzle height from the mud surface, nozzle outlet pressure, nozzle spray angle, nozzle height from the mud surface and nozzle outlet pressure affect the effective scouring depth
From the analysis of variance, it is clear that the interaction of nozzle outlet pressure X1 and nozzle angle X3 from the mud surface affects the test index, the other interaction terms have a non-significant effect on the test index
Summary
A popular aquatic vegetable, is being grown in China year after year. According to incomplete statistics, as of 2019, more than 60,000 hectares of lotus roots were grown in Hubei province. People with high-pressure water guns use water jets to impact the soil above the lotus roots, causing them to float upwards on their own buoyancy and complete the harvest. The water pump, delivery line and nozzles make up the hydraulic flushing system, which is arranged on the drive chassis This type of machine has sufficient power and is fitted with several nozzles, to improve operational efficiency. Less research has been carried out on high-pressure water jets with high flow rates, and research on hydraulic scouring systems for lotus root harvesters is essential. Its performance parameters are rated flow rate 162 m3·h−1 and rated head 78 m
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