An engineering modification of the blade element momentum combination applicable in vertical descent flight :fundamentals and validation

An engineering modification of blade element/momentum theory is applied to describe the vertical autorotation of helicopter rotors. A full non‐linear aerodynamic model is considered for the airfoils, taking into account the dependence of lift and drag coefficients on both the angle of attack and the Reynolds number. The proposed model, which has been validated in previous work, has allowed the identification of different autorotation modes, which depend on the descent velocity and the twist of the rotor blades. These modes present different radial distributions of driven and driving blade regions, as well as different radial upwash/downwash patterns. The number of blade sections with zero tangential force, the existence of a downwash region in the rotor disk, the stability of the autorotation state, and the overall rotor autorotation efficiency, are all analyzed in terms of the flight velocity and the characteristics of the rotor. It is shown that, in vertical autorotation, larger blade twist leads to smaller values of descent velocity for a given thrust generated by the rotor in the autorotational state.

An engineering modification of the blade element momentum equation for vertical descent : an autoration case study

An engineering modification of blade element/momentum theory is applied to describe the vertical autorotation of helicopter rotors. A full non-linear aerodynamic model is considered for the airfoils, taking into account the dependence of lift and drag coefficients on both the angle of attack and the Reynolds number. The proposed model, which has been validated in previous work, has allowed the identification of different autorotation modes, which depend on the descent velocity and the twist of the rotor blades. These modes present different radial distributions of driven and driving blade regions, as well as different radial upwash/downwash patterns. The number of blade sections with zero tangential force, the existence of a downwash region in the rotor disk, the stability of the autorotation state, and the overall rotor autorotation efficiency, are all analyzed in terms of the flight velocity and the characteristics of the rotor. It is shown that, in vertical autorotation, larger blade twist leads to smaller values of descent velocity for a given thrust generated by the rotor in the autorotational state.

Improved damage detectability in a wind turbine blade by optimal selection of vibration signal correlation coefficients

Piotr Omenzetter and Simon Hoell’s work within the Lloyd’s Register Foundation Centre for Safety and Reliability Engineering at the University of Aberdeen is supported by Lloyd’s Register Foundation. The Foundation helps to protect life and property by supporting engineering-related education, public engagement and the application of research.

Brogede blade : otte klaverstykker /

"Til min Datter Ludo Fabricius." -- T. p.

Peter Rørdam. Blade af hans levnedsbog og brevvexling,

Each vol. has also special t.-p.

A manual of sorrento and inlaid work for amateurs, with new and original designs.

Mode of access: Internet.

Investigation of helicopter rotor blade flutter and flapwise bending response in hovering

"Propulsion Laboratory, Contract no. AF33(616)-5210, Project no. 3137, Task no. 33113."

Boundary layer and wake modifications to compressor design systems : the effect of blade-to-blade flow variations on the mean flow field of a transonic rotor : final report, 01 September 1976-31 August 1978 /

"AFAPL-TR-79-2010."

Ge blade

Sichuan. Xindu. Shanhe town; 8 21/32 in.x 3 31/32 in.; bronze

Unearthed artifact. Ge blade with tiger design and inscription of Ba Shu Tu Yu

Sichuan. Pixian. Dubaishu; 9 59/64 in.x 5 23/64 in.; bronze

Unearthed artifact, Ge blade with tiger design

Sichuan. Chengdu. Baihuatan; L: 9 31/64 in.; bronze

Operator's organizational, DS, GS, and depot maintenance manual : tractor, full tracked, D.E.D., 7500 lb. min. drawbar pull, w/bulldozer blade, back rip scarifier, J.I. Case model M-450, FSN 2410-935-0714.

"December 1969."

Operator, organizational, field, and depot maintenance manual : grader, road, motorized, diesel engine driven, 12-foot blade, Caterpillar model 12, serial number range 99E5309 UP, FSN 3805-197-4184.

"June 1963."

Direct support and general support maintenance repair parts and special tools lists (including depot maintenance repair parts and special tools lists) : grader, road, motorized, DED, 13,000 lb pressure at blade, 12 foot blade, 6 wheels, 4 driving, 2 steerable, leaning front wheels, w/scarifier army model 440HA, NSN 3805-00-931-7881, army model 440HAROPS, NSN 3805-01-018-2866.

Includes index.