Insect flight is achieved by flapping the wings; during these movements the wing blade, twisted as it passes from elevation to depression, produces the same effect as the rotating propeller of an aircraft.
Open image in new window Figure 14 Power coefficients under different blade twist angles.
Ө p is the blade twist angle, measured from the plane of rotation.
It was found that the blade twist had a significant influence on the observed instability: a blade without a twist experienced a strong subcritical instability.
A data regression analysis was completed and found the impeller with 400° of blade twist to be the superior performer.
A refined range of blade twist angles between 300° and 400° was then identified, and 4 additional geometries were evaluated.
In Part II, we exploit material and structural bend-twist couplings in the main spar to induce appropriate differential blade twist, section by section, while bending flap-wise.
The flow pattern and power number in a vessel depend on the impeller blade angle, number of blades, blade width, blade twist, blade thickness, pumping direction and interaction of flow with the vessel wall.
The paper presents the effects of blade twist and nacelle shape on the performance of horizontal axis tidal current turbines using both analytical and numerical methods.
The blade twist due to elastic coupling is a required parameter for wind turbine performance evaluation and can be predicted through a finite element (FE) structural analyser.
Chord lengths, blade twist angles and rotational speeds were allowed to change independently so as to achieve a maximum energy output, while design constraints were also being met.
