Simultaneous Measurement in Nonisothermal Melt-Blowing Airflow Field: Time-Averaged and Turbulent Characteristics

Melt-blowing airflow, which involves converging jets of high-temperature and high-speed, is a nonisothermal turbulent flow. In this work, simultaneous velocity-temperature measurement has been accomplished for the first time to study the airflow under the nozzle of a melt-blowing slot die systematically. The time-averaged characteristics and turbulence characteristics are presented. The evolution of velocity, temperature, and turbulence intensity reveals the features during the merging and combing process of the nonisothermal air jets. By analyzing the turbulence and the bending of fiber under nonisothermal and isothermal conditions, we find that the turbulence distribution pattern in nonisothermal conditions helps intensify the bending instability of fiber under the nozzle.