Numerical simulation of flow field in single-head broken-tooth spiral extrusion dewatering channel

To investigate the influence of single-head interrupted-tooth spiral blades on the dewatering performance of screw-type solid-liquid separation equipment, this study employs the Eulerian multiphase flow model to numerically simulate the internal flow field during dewatering. Simulations are conducted for cylindrical shaft structures with single-head interrupted-tooth blades at three intermittent distance parameters (30, 40, 50 mm) and conical shaft structures with intermittent distances of 20, 30, and 40 mm. A comparative analysis was conducted on the operational performance of the single-head interrupted-tooth spiral under both shaft types, examining the internal flow field's particle volume fraction, solid phase velocity distribution, and pressure distribution within the dewatering compression zone. The study revealed that changes in particle volume fraction within the flow channel occurred in three distinct phases: the cylindrical shaft exhibited an overall large-wave oscillatory increasing trend, while the conical shaft showed a small-wave steady increasing trend. The dewatering performance of single-head interrupted-tooth spiral blades in the conical shaft structure significantly outperformed that in the cylindrical shaft. The cylindrical shaft structure with an 40 mm intermittent distance and the conical shaft structure yielded the optimal results in this numerical simulation, achieving solid phase volume fractions at the outlet of 48% and 55%, respectively. The intermittent distance significantly influences screw squeezing dewatering performance, as its length controls material residence time within the chamber. Pressure in the squeezing zone decreases with increasing intermittent distance in the cylindrical shaft. In the conical shaft, both the small-pitch and large-pitch models exhibit high pressure in the squeezing zone. This numerical simulation provides a basis for designing single-head interrupted-tooth spiral squeezing devices.