Secondary Flow in the Volute Casing of a Turbomachinery

Numerical calculations are especially suitable to capture phenomenon like secondary flows, which are difficult to be measured.

The animation at the top of the page shows the pressure field and the pressure gradients in the cross sectional plane of the casing at different time steps of the numerical calculations. It is to distinguish that at different time steps the pressure fluctuates strongly (color varies strongly); since the chosen cross sectional plane is located near to the tongue of the casing. The pressure gradients in the cross sectional plane are arising from the passage curvature (centrifugal forces) and they are in combination with boundary layers responsible for the secondary flows in the volute casing. The secondary velocity vectors at different time steps of the numerical calculations are shown in the animation at the bottom of this page.

According to the animations at each time step the centers of the vortices of the secondary flow correspond to the pronounced minimum value regions of the pressure field.