Fluid reaction surfaces (i.e. – impellers) – Specific working member mount – Turbo machine
Patent
1990-03-23
1991-10-08
Look, Edward K.
Fluid reaction surfaces (i.e., impellers)
Specific working member mount
Turbo machine
F03D 1104
Patent
active
050549995
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national phase application corresponding to PCT/SE88/00489 filed Sept. 21, 1988 and based, in turn, upon an application filed in Sweden as 8703294.2 filed Sept. 25, 1988 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to a flow machine and, more particularly, to a flow machine provided with a device for attachment of an adjustable blade element having an airfoil shape cross-section.
BACKGROUND OF THE INVENTION
A blade adjustment is one of the cardinal problems of any type of flow machine affecting equally a structural strength correlated with an operation of the machine at high speeds, safety of a structure and flow losses. A few principal structures of the flow machine are known. Axial machines with radial, non-adjustable blades, for instance, steam turbines, utilize a so-called fur top attachment meeting high operational demands as a result of a form-locking engagement. Hydraulic turbines, for example, Kaplan-type propeller turbine, utilize adjustable blades providing high efficiency and methods for adjusting the blades are known. Generally, blades are attached outside the flow area of medium driving an actual blade. However, design problems often arise when ,under certain circumstances, a blade should be attached within the flow area causing high flow losses.
In machines characterized by the medium flowing transversely to a blade of the machine, so called transverse flow machines, the blade attachment gains particular significance when such a machine is provided with a small number of blades.
The FRENCH patent 604,390 describes the importance of a stream line shape for the blades in a so called Darrius-rotor. Rotor blades in the transverse machines are exposed to a varying load causing a fatigue effect. Due to the high density of liquid, structural strength of the blade attachment gains a critical role for an entire structure. Particularly, designing a structure of the blade attachment, not only the operational speed, but also a run away speed, attained by a turbine upon interrupting of the breaking moment of a generator, should be taken into consideration.
In hydraulic turbines the run away speed is twice as high as the operational speed. Considering the influence of centrifugal forces, the ratio between the run away and operational speed is even larger rendering the run away speed to be approximately four times as high as the operational speed.
This phenomena affects detrimentally the machines with adjustable blades attached to an insert element during an operation by increasing the wear of the blades. As a result, additional structural demands are brought to both a structure of the insert element and sealing connections thereof preventing penetration of pollutants carried by the medium.
The known structures of a pivot element negatively affects the structure as well. As known in the art, a blade length with known blade attachments is to be extended at more than 20% of the blade length. As a consequence, the blade effectiveness is decreased at more that 30%.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved blade attachment.
Another object is the provision of such an improved blade attachment for a hydraulic turbine which overcomes the above-given disadvantages, that is reducing the wear of the blade upon improving sealing connections and configuration of the insert element.
SUMMARY OF THE INVENTION
According to the invention a flow machine includes:
a rotor rotatable about an axis of rotation;
at least one support arm mounted nonrotatably on the rotor and extending radially from the axis, the arm being formed with a free end spaced from the rotor;
at least one pin operatively connected with the free end and pivotal about a pivot axis parallel to the axis of rotation;
a surface formed by a straight line generatrix moved about an airfoil shape closed path parallel to the pivot axis;
a body formed with the surface and having a longitudinal a
REFERENCES:
patent: 955289 (1910-04-01), Scott
patent: 1835018 (1931-12-01), Darrieus
patent: 4105363 (1978-08-01), Loth
patent: 4183715 (1980-01-01), Ducker
patent: 4255085 (1981-03-01), Evans
patent: 4299537 (1981-11-01), Evans
patent: 4430044 (1984-02-01), Liljegren
patent: 4435124 (1984-03-01), Zheng
patent: 4555218 (1985-11-01), Jonsson et al.
Dubno Herbert
Jonsson Pumpkonsult
Kateshov Yuri
Larson James A.
Look Edward K.
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