sin αst

LIST OF ATTACHMENTSROTOR THEORY
134
� There is no aerodynamic interaction between the elements (no radial flow)
� The forces on the blades are determined solely by the lift and drag characteristics
of the blade airfoil
The differential contribution to axial force (thrust) is
Whereby the total axial forces can be calculated from
The differential contribution to torque is
1
dT
2 � W2 = c B Cy dr
R
1
T B
r
2
0
� W 2 �
= � c Cy d
�
�
1
dQ
2 � W2 = c B Cx r dr
From which the total torque and the power may be calculated
R
1
Q B
r
2
0
� W 2 �
= � c Cx r d
�
�
R
1
Pr � B
r
2
0
� W 2 �
= � c Cx r d
�
�
The rotor efficiency may be calculated by
The efficiency may also be denoted by a Cp value
� r
C p
=
P r
P betz
16
27 � =
r
Using the described BEM theory and iterative calculation methods, it is possible to deter-
(B.11)
(B.12)
(B.13)
(B.14)
(B.15)
(B.16)
(B.17)
mine the axial force (thrust) and tangential force (torque) on annular sections of the rotor
as a function of flow angles and airfoil characteristics. This makes it possible to determine
the rotor performance for an arbitrary blade shape, which is done via the developed calcu-
lation tool, described in appendix C. It is additionally possible establish the ideal shape of a