| Rotor spinning is a kind of air spinning,which mainly uses air flow to remove impurities,transport fibers,and twist fibers into yarn.As the core component of the spinning machine,the rotor cup uses air flow to slip,assemble and twist the fibers from the transport channel into yarn.The air flow almost participates in the whole spinning process and is closely related to the quality of the yarn.Therefore,it is of great significance to study the characteristics of the airflow field in the rotor cup and then optimize the spinning process and structural parameters.As a typical mechanism,the rotor cup has strong turbulence inside and a very complex airflow.In this paper,the research object is an aspirated rotor spinner.Firstly,the theoretical calculation model of the rotor cup is established using Large Eddy Simulation(LES),and the air flow characteristics of the rotor cup are analyzed from the aspects of pressure,velocity,and vortex.Secondly,the influence of rotor structural parameters,such as diameter,slip surface angle,and wall defects,on the airflow field in the rotor was explored,and then the suggestions for the structure of the spinner were proposed;Finally,a combination of simulation and PIV experiments was used to analyze the rotor airflow characteristics at different rotor speeds.The research results of this paper are as follows:1.Compared to the RANS turbulence model,the LES is more accurate in solving the airflow pressure and velocity characteristics,and well captures the small-scale vortex structures in the rotor cup,providing us with more detailed flow information.2.The slip surface angle,diameter,and wall defects of the rotor can affect the airflow distribution,which in turn affects fiber movement.Changing the slip surface angle while other conditions remain unchanged,when the slip surface angle is about 64 °,there are fewer vortices inside the rotor,which is conducive to fiber movement.When the diameter of the rotor increases,the rotor has enough space to accommodate the airflow,and the airflow disorder is alleviated to some extent.However,when the diameter is too large(56mm and 60 mm),the velocity of the rotor groove fluctuates greatly,so the diameter is best not to exceed 56 mm.A small number of defects on the wall surface may slow down the overall turbulence of the air flow,but it is still necessary to replace the rotor in time when defects exceed a certain degree.3.In this paper,PIV technology is used to study the airflow field of a rotor with different rotor speeds.From the simulation and experimental results,it can be seen that the speed of the cup wall is large,while the middle part velocity is low.When the rotor speed is too low(60000 rpm and 80000 rpm),the internal flow field of the rotor is relatively disordered.When the rotor speed is too high(120000 rpm and 150000 rpm),many small and disordered vortices are generated in the downstream and central regions of the rotor,which are not conducive to the movement of the yarn.Therefore,100000 rpm may be more suitable under these conditions.The comparison between simulation and experiment shows that the macro results are basically consistent,which indicates the feasibility of large eddy simulation,and verifies the reliability of the simulation results of the flow field in the rotor at different rotor speeds. |
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