The following set of graphs shows how the calidation model works, using as an example the flow through a a sudden contraction. The volume under tension (below vapour pressure) is identified and bubble nucleation starts. Bubbles grow/collapse as they travel through the flow channel. Vapour production leads to pressure recovery, drop in the volumetric flow rate and increase in the injection velocity.

(click images for animation)

Formation of cavitation in the low pressure region (right) and volume under tension reduction (left) associated with the formation of cavitation

Prediction of single-bubble dynamics along trajectories of bubbles with different initial size

Predicted volumetric flow rate reduction, effective area increase at the hole exit and tension volume reduction relative to the single-phase flow calculation.

(click images for animation)

Application of the model to a six-hole VCO nozzle operating at 1200bar, for two different needle lifts of 20 and 350microns. The images show the recirculation zones formed inside the 'sac' volume and cavitation onset and further development.

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