| 1. |
|
|
| 2. |
|
|
| 3. |
- Chernysheva, Olga V., et al.
(författare)
-
Influence of a vibration amplitude distribution on the aerodynamic stability of a low-pressure turbine sectored vane
- 2006
-
Ingår i: Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity of Turbomachines. - Dordrecht : Kluwer Academic Publishers. - 1402042671 ; , s. 17-29
-
Konferensbidrag (refereegranskat)abstract
- A parametrical analysis summarizing the effect of the reduced frequency and sector mode shape is carried out for a low-pressure sectored vane cascade for different vibration amplitude distributions between the airfoils in sector as well as the numbers of the airfoils in sector. Critical reduced frequency maps are provided for torsion- and bending-dominated sector mode shapes. Despite the different absolute values of the average aerodynamic work between four-, five- and six-airfoil sectors a high risk for instability still exists in the neighborhood of realistic reduced frequencies of modern low-pressure turbine. Based on the cases studied it is observed that a sectored vane mode shape with the edge airfoils in the sector dominant provides the most unstable critical reduced frequency map.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Kielb, R., et al.
(författare)
-
Flutter of low pressure turbine blades with cyclic symmetric modes : A preliminary design method
- 2004
-
Ingår i: Journal of turbomachinery. - : ASME International. - 0889-504X .- 1528-8900. ; 126:2, s. 306-309
-
Tidskriftsartikel (refereegranskat)abstract
- A current preliminary design method for flutter of low pressure turbine blades and vanes only requires knowledge of the reduced frequency and mode shape (real). However many low pressure turbine (LPT) blade designs include a tip shroud that mechanically connects the blades together in a structure exhibiting cyclic symmetry. A proper vibration analysis produces a frequency and complex mode shape that represents two real modes phase shifted by 90 deg. This paper describes an extension to the current design method to consider these complex mode shapes. As in the current method, baseline unsteady aerodynamic analyses must be performed for the three fundamental motions, two translations and a rotation. Unlike the current method work matrices must be saved for a range of reduced frequencies and interblade phase angles. These work matrices are used to generate the total work for the complex mode shape. Since it still only requires knowledge of the reduced frequency and mode shape (complex), this new method is still very quick and easy to use. Theory and an example application are presented.
|
|
| 7. |
|
|
