Simulation analysis of flow field characteristics of power law fluid in single screw

doi:10.19491/j.issn.1001-9278.2025.06.012

Abstract

Abstract:

This study focuses on power⁃law fluid dynamics within a three⁃dimensional single⁃screw model. Numerical methods were employed to analyze the flow behavior of power⁃law fluids， and the ANSYS Polyflow software was utilized to simulate their flow patterns in the 3D screw geometry. Dimensionless parameters were adopted to ensure the generalizability of the results. First， the relationship between screw throughput and pressure gradient under varying power⁃law indices was calculated to validate the simulation method’s accuracy. Subsequently， flow field characteristics， including velocity， shear rate， and viscosity profiles along the depth of the screw channel， were extracted and analyzed， with emphasis on their variations under different power⁃law indices and pressure gradients. The study concluded with key findings on power⁃law fluid flow dynamics. Notably， as the power⁃law index decreases， the pressure⁃driven flow field of the fluid intensifies， leading to diminished screw conveying capacity. This is reflected in the viscosity field： reduced viscosity near the upper and lower surfaces of the screw channel weakens the response of fluid to screw⁃induced propulsion， ultimately decreasing conveying efficiency and potentially inducing reverse flow.

Key words: power law fluid, single screw, melt transport, pressure flow, ANSYS polyflow

CLC Number:

TQ320.66⁺3

SONG Yumo, DONG Lijia, LI Guosheng, WANG Jinxia. Simulation analysis of flow field characteristics of power law fluid in single screw[J]. China Plastics, 2025, 39(6): 59-65.

Figures/Tables 14

Fig.1. Schematic diagram of single screw parameters

Fig.2. Single screw geometric model

参数名称	数值
螺杆长度L/m	0.7
机筒内径D_b/m	0.1
螺杆根径D_s/m	0.09
槽深h/m	0.005
螺距t/m	0.1
螺棱法向宽度e/mm	9.53
螺槽法向宽度/mm	85.76
螺距角φ_b/°	17.66

Tab.1. Single screw model parameters

Π_p	n=0.2	n=0.4	n=0.6	n=0.8	n=1.0
0	0.00	0.00	0.00	0.00	0.00
0.1	17.23	17.07	16.90	16.74	16.58
0.2	34.47	34.14	33.81	33.48	33.16
0.3	51.70	51.20	50.71	50.23	49.74
0.4	68.93	68.27	67.62	66.97	66.32
0.5	86.17	85.34	84.52	83.71	82.90

Tab.3. Relationship between outlet pressure pi and power law index

Fig.3. Power law fluid material characteristic curve

Fig.4. Relationship between output and pressure gradient of single screw with different power law indices based on numerical simulation （dimensionless）

Fig.5. Mesh of single screw model

方案编号	径向网格数量/个	轴向网格数量/个	周向网格数量/个	网格总数/万
1	10	150	100	15
2	15	200	120	36
3	20	250	120	60
4	20	300	160	96

Tab.4. Four mesh parameter Settings for grid independence verification

Fig.6. Schematic diagram of the position of the section used for the results

Fig.7. Comparison of axial velocities of spiral groove fluids in different mesh schemes （dimensionless）

Fig.8. Mesh for the final selection of single⁃screw flow field analysis

Fig.9. Radial velocity profile in the spiral groove under different pressure gradients

Fig.10. Pressure of barrel inner surface n=1， Πp=0

Fig.11. Radial shear rate and viscosity profiles in the spiral groove under different pressures

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