2. Oblique towing test at low speed and large drift
angle
2.1 Test prnciples
The drift angle ( = a tan (v, u) ) will be changed
to large extent due to the very slow rotation motions
of underwater vehicle, and the forces affected by position will also be altered. To obtain the hydrodynamics
model of oblique motions for the vehicle, the
fluid dynamics are divided into the following components:
ideal fluid force (munk), linear lift ( ), induced
drag (
v L
st D ), transverse flow resistance ( ), longitudinal
resistance (
Yc
f X
X
) and asymmetrical lift along
longitudinal direction ( ). Figure 3 illustrates the
forces acted on the vehicle in detail.
las
According to the above forces, the fluid dynamics
model of underwater vehicles at low speed and
large drift angles is derived as the following dimensionless
formula