Wind-induced breakup

First Wind-Induced Breakup (Sinuous Wave Breakup) Surface Tension Force, Dynamic Pressure of Ambient Air 1.2 + 3.41Oh09 < We <13... 

Second Wind-Induced Breakup (Wave-like Breakup with Air Friction) Dynamic Pressure of Ambient Air 13[Pg.131]

III. Second Wind-Induced Breakup. Further increasing jet velocity, the dynamic pressure of the surrounding air becomes predominant. The breakup of the jetis caused by the unstable growth of short-wavelength surface waves due to the relative motion between thejet and the surrounding air. The maximum growth rate occurs at... 

Fig. 27.2 Jet stability curve dripping flow (A-B-C), Rayleigh breakup (C-D), wind-induced regime (D-F), atomization regime (F-G oiH)...

Fig. 22.10 Plot of the mean drop size for different process conditions depending on the gas-Weber number. The drop size up to a critical value increases slowly with increasing gas velocity. Above this critical gas-Weber number, the drop size rises suddenly. This can be explained by the transition of the breakup regime from axisymmetric breakup to wind-induced breakup. The oscillating thread is more sensitive to this transition, as the critical gas-Webta-number is reached earlier for similar process conditions...

Fig. 22.11 Two threads emerging from open channel flow with different dimensionless viscosities. In (a), the thread disintegrates due to surface-driven axisymmetric or Rayleigh wave breakup. The cross-wind flow leads to a slight increase in drop size, (b) Shows a different breakup mode, as the stronger cross-flow initiates a more stochastic-wind induced breakup...

Based on data series that show this transition within the measured range, a prediction for the critical gas-Weber number is developed. The critical gas-Weber number marks the cross-wind velocity above which the breakup is dominated by wind-induced breakup and it depends on the dimensionless flow rate and viscosity. Equation (22.12) gives the prediction for completely filled capillaries [11]. 

The results also elucidate the influence of the cross-wind flow on the drop formation from laminar threads in the range of typical process condition for the LamRot. The drop size increases slightly due to the effect of shorter breakup length. The theory of increasing wave number [32] does not fit in case of stretched threads. The relevance of the slight increase below the transition to wind-induced breakup for the design of a spray process with the LamRot is low. 

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