Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Radial flow devices
Reexamination Certificate
1999-07-30
2001-09-18
Lopez, F. Daniel (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Radial flow devices
C416S238000, C416S21900R
Reexamination Certificate
active
06290465
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to turbine engines, and more specifically, to a blade for a compressor for such engines.
A turbine engine typically includes a fan and a low pressure compressor, sometimes referred to as a booster. The fan includes a rotor having a plurality of blades. The low pressure compressor also includes a rotor having a plurality of rotor blades which extend radially outward across an airflow path. The fan rotor is coupled to the booster rotor. The blades generally include an airfoil section mounted radially outward of a blade root section. The rotor is housed within a stator case.
During engine certification, a test sometimes referred to as a “blade out” test is run. In the blade out test, a fan blade is released at its root, which creates an imbalance in the fan rotor. Since the fan rotor is coupled to the booster rotor, the imbalance in the fan rotor affects operation of the booster rotor. Specifically, the blade tips can rub the case. The radial and tangential loads imposed by the blade tips on the case create stresses in the case, which can lead to unexpected failure of stator case skin or flanges.
To withstand such stresses, the strength of the stator case can be increased. For example, the material used to fabricate the stator case can be selected so as to have sufficient strength to withstand stresses caused by rubbing of the rotor blades. Also, and rather than using other materials, thicker flanges, thicker stator skin, and additional bolts can be added to increase the stator strength. Increasing the stator case strength, however, typically results in increasing the weight and cost of the engine.
BRIEF SUMMARY OF THE INVENTION
Rotor blades and vanes for a turbine engine which are configured to more easily bend, or buckle, than known rotor blades and vanes are described. In an exemplary embodiment, a rotor blade includes a blade root section and an airfoil section configured to more easily bend, or buckle, than known airfoil sections. Providing that the airfoil section more easily bends, or buckles, facilitates reducing the forces on, and damage of, stator components during a blade out event.
In one specific embodiment, the blade airfoil section extends radially outward along a radial line R
AS
from the blade root section. The radial line R
AS
extends at an angle relative to a plane extending across a top surface of a platform between the airfoil section and the blade root section, rather than normal, or perpendicular, to such plane. As a result, and during a blade out event, an over turning moment is generated in a root of the airfoil section. The overturning moment facilitates bending the airfoil section.
REFERENCES:
patent: 2962260 (1960-11-01), Foley
patent: 4131387 (1978-12-01), Kazin et al.
patent: 4460315 (1984-07-01), Tseng et al.
patent: 5249922 (1993-10-01), Sato et al.
patent: 6071077 (2000-01-01), Rowlands
Kray Nicholas J.
Lammas Andrew J.
General Electric Company
Herkamp Nathan D.
Hess Andrew C.
Lopez F. Daniel
Woo Richard
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