Suppose we have a cylindrical vortex chamber with one exit pipe at the top.

( like here : https://ars.els-cdn.com/content/image/1-s2.0-S092188311830520X-gr2.jpg )

The air comes inside through the tangential inlets in the walls.

The pressure at the exit is Pe = Pa - Pd

where Pa - ambient pressure, Pd - constant draft

The pressure in the middle of the vortex chamber will be Pm = Pa - Pv

where Pv - vacuum created by vortex chamber

Pv will depend on the shape of the chamber and Pd

What shape of chamber should we choose to achieve maximum Pv at given Pd ?

Is there a formula or empirical table that links maximum Pv with given Pd?