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.

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