Normal force and moment of a ship moving obliquely
1956 Volume 1956 Issue 90 Pages 31-37
Details
1956 Volume 1956 Issue 90 Pages 31-37
The normal force coef. CN of normal force acting on a low aspect ratio rectangular plate is
CN=2π/1+2/kcosα sin a cosα+2 sin2α
where k is aspect ratio, α is angle of attack
The 1st term is the Prandtl's wing theory and the 2nd term is the Newton's resistance law of a plate and the value of CN when k=0.
The moment coef. Cm about middle point of the plate is
Cm=f(k) sin αcos α
where f(k) is the calculated value.
and some pure moments are added to the moment by Prandtl's wing theory. The former is not neglegible for the latter.
When a ship, k is 0.10.2 and she has breadth. In this case the 1st term in CN is not changed much, but 2nd term shows the variation by her breadth. In the case of moment about _??_ the effect due to breadth of pure moment is not known, so I start from Munk's formula, multiply this value by some theoretical value and gain the ship's moment. These values agree with the experimental value in the case of the plate and also the ship.
