Engineering Transactions, 61, 2, pp. 99–117, 2013
10.24423/engtrans.23.2013

Failure Analysis (Experimental and Numerical Approach) of Gas Turbine Generator Cooling Fan in Comparison between using 2types (14◦ and 19◦ Angle of Attack) of Blades

Ali JAHANGIRI
Semnan University, Faculty of Mechanical Engineering, Semnan
Iran, Islamic Republic of

Seyed Ebrahim Moussavi TORSHIZI
NRI – Niroo Research Institute, Tehran
Iran, Islamic Republic of

Seyed Majid Yadavar NIKRAVESH
Power & Water University of Technology, Tehran
Iran, Islamic Republic of

In gas turbine power plants, a fan is used as a cooling system to dissipate generated heat in coils (copper conductors) and generator electric circuits at the end sides of its rotor. In some cases, fracture of blades causes a short circuit between rotor and stator and consequently generator explosion and financial problems. The fracture of cooling fan blades has occurred five times at the turbine side of the generator in our case of study, just 100hr after resuming operations after an overhaul. Using numerical analysis as well as laboratory investigation – including visual inspections, metallography and SEM – can help better find failure problems that cause blade failures. A series of numerical analysis was performed to diagnose the possible cause of failure. CFD analysis is used to study the airflow distribution in order to observe probable separation phe- nomenon and pressure forces as they are imposed on fan blades due to operation. A finite element method was utilized to determine the stresses and dynamic characteristics of the fan blade (natural frequencies, stresses and vibrations). Key words: fatigue failure, dimple rupture, fan blade, scanning electron microscope (SEM), resonance, fan blade angle of attack, computational fluid dynamic (CFD), finite elements.
Keywords: fatigue failure; dimple rupture; fan blade; scanning electron microscope (SEM); resonance; fan blade angle of attack; computational fluid dynamic (CFD); finite elements
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Copyright © Polish Academy of Sciences & Institute of Fundamental Technological Research (IPPT PAN).

References

Alsthom Company report in conjunction with some Gas Power Plants (1997).

Anderson L., Fracture mechanics fundamental and applications, CRC Press, 9780849316562, Colorado, USA (1995).

Barlow K.W., Chandra R., Fatigue crack propagation simulation in an aircraft engine fan blade attachment, Int. J. Fatigue, 27, 1661–1668, 2005.

Beisheim J.R., Sinclair G.B., On the three-dimensional finite element analysis of dovetail attachment, [in:] Proceedings of ASME Turbo Expo 2002, Amsterdam, The Netherlands (2002).

Failure analysis report of Iran-Montazer-Ghaem units 2, 4 & 6. Iran Power Plant Repair Co, (2003–2004).

Hou J., Bryon J.W., Ross A., An investigation of fatigue failures of turbine blades in a gas turbine engine by mechanical analysis, Engineering Failure Analysis, 9, 201–211, 2002.

Hutson A., Nicholas T., Johnc R., Fretting fatigue crack analysis in Ti-6Al-4V, Int. J. Fatigue, 27, 1582–1589, 2005.

Joseph R., ASM Specialty Handbook, Aluminum and aluminum Alloys, ASM International, 087170496X, USA (1993).

Moussavi Torshizi S.E., Yadavar Nikravesh S.M., Jahangiri A., Failure analysis of gas turbine generator cooling fan blades, Engineering Failure Analysis, 16, 1686–1695, 2009.

Paris P.C., Gomez M.P., Anderson W.E., A rational analytical theory of fatigue, Trend Eng., 13, 1, 9–14, 1961.

Poursaeidi E., Salavatian M., Failure analysis of generator rotor fan blades, Engineering Failure Analysis, 14, 851–860, 2007.

Poursaeidi E., Salavatian M., Fatigue crack growth simulation in a generator fan blade, Engineering Failure Analysis, 16, 888–898, 2009.

Xi N.S., Zhong P.D., Huang H.Q., Yan H., Tao C.H., Failure investigation of blade and disk in first stage compressor, Eng. Fail Anal., 7, 385–392.

http://www.cfg.cornell.edu/software/software.htm.




DOI: 10.24423/engtrans.23.2013