Velocity component normal to the shroud avia.

[urusal]

Здравствуйте, не очень понятно про составляющую скорости, то есть она будет нормальной по отношению к корпусу?

With regard to FS, it is useful to first review the flow physics attendant to the shrouded prop systems. As discussed in Ref. 1 for example, in the shrouded flow depicted in Figure 4, any axial pressure change due to, for example, a prop causes the flow streamlines upstream and downstream to expand or contract laterally, giving rise to a velocity component normal to the shroud. Because of this, the Kutta-Jackowski theorem than requires that its interaction with the ring vortex vector associated with the duct’s circulation produces an axial force, FS.
The critical aspect of this model is that it relates the axial force on the shroud solely and directly to the force on the fluid caused by the axial change in the pressure. From this and dimensional analysis considerations, the current formulation sets the shroud axial force (see Figure 1 for nomenclature) as being proportional to the prop induced force through a shroud coefficient, Cs

спасибо!

[Себастьян Перейра, торговец черным деревом]

Перпендикулярно.
Вектору.