New correlation formulae for the straight section of the electrospun jet from a polymer drop

Abstract

AbstractAn electrospun polymer jet issued from a Taylor cone follows a straight-line motion before experiencing electrical bending instability resulting in curling and spiralling of the jet in three-dimensional space. Experiments are performed to characterize the fluid dynamics of an electrospun polymer jet. Appropriate image processing is performed to systematically analyse flow regimes of the electrospun jet. These regimes include Taylor cone formation/jet initiation and the straight section of the jet. Dimensional analysis was performed to identify the salient dimensionless parameters, which govern the electrospun jet characteristics. Three new correlation formulae were obtained to characterize the dimensionless jet diameter at the apex of the Taylor cone $(\tilde {d} = 1. 03{\tilde {Q} }^{0. 44} )$, the dimensionless jet diameter at different locations along the jet’s straight section $(\tilde {d} {\tilde {z} }^{1/ 4} = 1. 09{\tilde {Q} }^{1/ 2} )$, as well as the length of the straight section of the jet $({\tilde {Z} }_{in} = 86{\tilde {Q} }^{0. 42} )$. These correlation formulae are valid for the analysed range of dimensionless flow rates $(2. 6{{\times 10}}^{- 4} \lt \tilde {Q} \lt 3. 6{{\times 10}}^{7} )$ and dimensionless electric fields $(7. 4{{\times 10}}^{- 4} \lt \tilde {E} \lt 1. 4{{\times 10}}^{- 1} )$. In addition, the correlation formulae are valid for the analysed range of Deborah numbers De and Reynolds numbers Re based on nozzle radius, $3. 3\times {10}^{- 7} \lt {\mathit{De}}_{{r}_{o} } \lt 3. 8\times {10}^{- 2} $ and $5. 8\times {10}^{- 4} \lt {\mathit{Re}}_{{r}_{o} } \lt 7. 0\times {10}^{- 1} $. The proposed new correlation formulae are instrumental in the design as well as controlled manipulation/optimization of the electrospinning phenomenon.