Improved Fiber Hydroentanglement Using Pulsed Elliptical Jets

Recent studies of impinging jet flows have shown that momentum and heat transfer can be significantly improved if the jet flow is pulsed (Zumbrunnen, 1996). Moreover, when the jet holes are elliptical, jet free surfaces are formed into a helical structure. These helical structures in a jet flow can be readily observed by squeezing a garden hose into an elliptic shape. Upon pulsating the jet flow, the helical structure rotates and a strong twisting action can be imparted where the jet strikes a surface. The helical structure has greater definition in jets of very small diameter, such as those used in hydroentanglement systems, since surface tension forces are larger. Pulsations and elliptic free surfaces in impinging jet flows may thereby be an effective means of improving fiber entanglement. Pulsations might also be used to impart unique patterns in nonwoven fabrics since jet-to-jet interaction can be altered by changing pulsation frequency and magnitude. With this rationale, our objective is to perform controlled experiments where the effect of flow pulsations and jet hole shape on fiber entanglement is investigated. The extent of entanglements will be quantified for different pulsation frequencies and amplitudes and for elliptic jet holes of different aspect ratios. The entanglement performance of elliptic and standard circular holes will be compared.