Two completely different approaches have been used to study
the mechanism of the air-jet method of bulking filament yarns.
Part A is an aerodynamic study of the nature of the air flow
and of its characteristics, and of the yarn's behaviour during the
bulking process. The experimentation involves the use of
scaled-up models of the du Pant type 9 commercial Taslan air-jet
and of a typically used parent yarn. The study is extended to
include a modification of the jet suggested by earlier workers.
The results of these investigations provide new evidence regarding
the mechanism of the process and the construction of bulked yarns
of this type. It is also concluded that the commercially used
air-jet on which the model study has been based, is not ideally
designed from the stand-point of efficiency, stability and ease
In Part B, a suggested mechanism of the air-jet bulking
action is simulated by a purely mechanical means. The simulation
of the process has been so effective that yarns of the air-jet
bulked type are produced by a method not requiring any compressed air.
The preliminary work leading to the design of an experimental
apparatus is briefly reported. Theoretical and experimental
investigations of the process are made, and the bulked yarn properties
for various parent yarn particulars and processing conditions are
measured and assessed. An economic evaluation of the process has
been attempted, based on a comparison with the limited cost figures
available for Taslan processing.
- The individual nature of each of the two main investigations
has necessitated that the results should be separately
discussed in the ultimate Chapter of each Part of the thesis.
Suggestions for further work are also made for each of the two
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.