Study on the effects of the characteristics of a vortex on splice strength in pneumatic yarn splicing

Abstract

Pneumatic yarn splicing is a complex process that involves the simultaneous movement of two strands of counter-rotating yarn. Depending on the process and structural parameters of the mingling chamber, the airflow field is more dominant in influencing the wrapped effectiveness of untwisted filaments and consequently the splice strength. This study establishes a computational domain of a mingling chamber comprising an inlet channel, accelerating channel, rotating channel, and groove channel. The renormalization-group k–ε turbulence model is adopted to simulate the vortex patterns in the rotating channel under different inlet pressure. Furthermore, a transient mass flow test bench based on the isothermal principle is used to verify the numerical simulation results by comparing the mass flow of a pneumatic splicer. A wrapped model of spliced yarn is presented to describe the effects of wrapped force determined by the characteristic of vortex patterns on the strength of spliced yarn. A strength tester is also used to acquire the strength of spliced yarn produced under different inlet pressures and interpret the reliability of theoretical analysis. Comparisons between numerical results and experimental data show that the inlet pressure of the mingling chamber clearly affects the vorticity of the vortex and the strength of spliced yarn. The vorticity of the vortex will be enhanced with increasing inlet pressure and improve splice strength to avoid insufficient twisting of the yarn end. However, excessive twisting of the yarn end, as reflected by splice strength, would occur if the inlet pressure strengthens continually.