Tandem fan stage for gas turbine engines
First Claim
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1. A fan assembly for a turbofan gas turbine engine, wherein the fan assembly includes:
- a fan disk;
a case circumscribing the fan disk and spaced apart therefrom to form a flowpath for working medium gases between the disk and the case;
a plurality of principal fan blades extending outwardly from the fan disk and across the flowpath for working medium gases into proximity with the circumscribing case, each blade having a camber angle which is sufficiently low such that the fundamental natural frequency of the blade in bending is less than the 2E multiple of engine rotor speed between flight idle and maximum power conditions for the turbofan engine in which the blade is installed;
a plurality of secondary fan blades at least one each corresponding to each principal blade and extending outwardly from the rotor disk near the trailing edge of the corresponding fan blade only partially across the flowpath for working medium gases wherein each principal fan blade and corresponding secondary fan blades form in composite the aerodynamic equivalent of a single blade having a camber greater than that of the principal fan blade.
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Abstract
A fan rotor assembly having decreased susceptibility to vibratory damage is disclosed. In one embodiment described the rotor assembly includes a plurality of principal fan blades 22 and a plurality of secondary fan blades 36 associated therewith. The secondary blades are coextensive with the principal fan blades over the inner portion of the principal blade span.
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Citations
5 Claims
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1. A fan assembly for a turbofan gas turbine engine, wherein the fan assembly includes:
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a fan disk; a case circumscribing the fan disk and spaced apart therefrom to form a flowpath for working medium gases between the disk and the case; a plurality of principal fan blades extending outwardly from the fan disk and across the flowpath for working medium gases into proximity with the circumscribing case, each blade having a camber angle which is sufficiently low such that the fundamental natural frequency of the blade in bending is less than the 2E multiple of engine rotor speed between flight idle and maximum power conditions for the turbofan engine in which the blade is installed; a plurality of secondary fan blades at least one each corresponding to each principal blade and extending outwardly from the rotor disk near the trailing edge of the corresponding fan blade only partially across the flowpath for working medium gases wherein each principal fan blade and corresponding secondary fan blades form in composite the aerodynamic equivalent of a single blade having a camber greater than that of the principal fan blade. - View Dependent Claims (2, 3, 4, 5)
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Specification
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Current AssigneeUnited Technologies Corporation (Rtx Corporation)
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Original AssigneeUnited Technologies Corporation (Rtx Corporation)
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InventorsStargardter, Hans
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Primary Examiner(s)NOT, DEFINED
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Application NumberUS06/434,215Time in Patent Office922 DaysField of Search416/231 B, 416/201 R, 416/200 R, 416/200 A, 415/119, 415/181, 415/DIG. 1, 415/213 CUS Class Current416/231.00BCPC Class CodesF01D 5/142 of the blades of successive...F01D 5/146 of blades with tandem confi...F01D 5/16 for counteracting blade vib...F04D 29/321 for axial flow compressorsF04D 29/324 BladesY10S 415/914 Device to control boundary ...
