Hi, I´m a senior year Mechanical Engineering Student, I´m writing this post because I need some advice from engineers with experience in rotordynamics for my internship project. Summarizing, the subject of the project is about studying the impact of inverting rotation of an axial Steam Turbine model 503T (two stages, non-condensing) manufactured by Dresser-Rand and how this change will impact the performance and life of the mechanical components of the turbine.

At this moment the turbine is at the workshop and repair duties are being made to allow the turbine to rotate counter wise. However I figured out that forces and moments will change of direction after the reparation. Since the stresses distribution will change I´m doubtful about whether this could affect the dynamic behaviour of hydrodynamic bearings (say oil film thickness, damping, etc.) , foundations and other components of the turbine and therefore vibration amplitudes. 

I will really appreciate your comments about this issue, since I have limited understanding of rotordynamics. Thanks in advance.

PS: The turbine shaft is supported by two radial sleeve bearings which are tilting pad type and one thrust ball bearing.turbine diagramturbine diagram2g.

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Yes some  engineers did, but Dresser didn´t provide further details, they just said "It´ll work". The running test is in two weeks from now , that day they should give us full details of the turbine behaviour and modifications performed,however I would like to have enough information  to support my research and know what to expect during the test.

I assume that steam inlet and outlet have the same function, and that the inlet nozzle is modified to change the admission angle on the rotor buckets; correct?

Do the rotor buckets/blades have symmetrical shape so that performance is unaffected? 

What about lube oil pump and speed governor suitable for reverse direction?

If assumption is correct, then thrust bearing, radial bearings, and foundation should not be affected (my best guess). 

School project?

Walt

You´re quite right, the inlet nozzle shall be modified. The governor is a Woodward TG611-17 and can be adjusted to work in reverse direction

Regarding the rotor and lubrication of bearings , we don´t know exactly how they manufactured the new rotor-stator set and whether lubrication of bearings is suitable in both directions, the manufacturer should´ve provide that information but they didn´t.

I think is interesting to assume that the manufacturer didn´t built a mirror version of the rotor, how about if they adapted one from anexisting turbine model, Could this change the rotordynamic behavior of the model? 

Rotor dynamics change if the mass-elastic properties of the rotor (wheel and shaft) change. If there are no significant differences and operating speed is the same and balance tolerance is the same, then vibrations should be about the same. Be aware that tilt pad bearings may be affected by rotation direction and require replacement. I hope you have a really good reason for the direction change!

Walt

Jose,

There are components in the turbine that are sensitive to the direction of rotation. So, all of these must be considered.

Examples of these components are the shaft-mounted parts that are threaded. The normal direction of rotation usually supports keeping these parts tightened, the opposite direction can undo the threads. Some coupling hubs are threaded.

There are stationary parts that are designed and located to stop the rotation of parts like anit-rotation pins. If the bearings are forced-lubrication, then the ports of the oil supply and drain need checking.

Please share with us your update and good luck with your project.

Regards- Ali M. Al-Shurafa

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