In the turbine and gear set shown in the...

Question 1 of 270705eccefa0bacbc34ba4d470e5

In the turbine and gear set shown in the illustration, when going astern, the minimum tolerable clearance between the rotor and intermediate or guide blading is __________. See illustration SE-0016.

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Question 1 of 27070

In the turbine and gear set shown in the illustration, when going astern, the minimum tolerable clearance between the rotor and intermediate or guide blading is __________. See illustration SE-0016.

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🔍 Key Concepts

• Clearance between rotor blades and stationary (intermediate/guide) blades in a marine steam turbine • How turbine rotor expansion and movement (ahead vs astern) affects minimum safe clearances • Consequences of too little vs too much clearance on blade rub, damage, and turbine efficiency

💭 Think About

• Think about what happens to the rotor position and thermal expansion when the turbine is operated astern instead of ahead. Does the rotor move toward or away from the guide blading? • Which of the listed clearances would be large enough to avoid contact during expansion and shaft movement, but still small enough to keep steam leakage and efficiency losses within acceptable limits? • Compare the options: which values are more typical for blade tip-to-diaphragm clearances in medium‑sized marine turbines rather than for very fine clearances like journal bearings?

✅ Before You Answer

• Be sure you understand which parts in the illustration are the rotor blades and which are the intermediate/guide (stationary) blades. • Mentally allow for thermal expansion and axial movement of the rotor when changing from ahead to astern and estimate how much additional clearance is needed to prevent rubbing. • Before choosing, rule out any value that seems too small to prevent rubbing under worst‑case expansion or so large that it would cause excessive steam leakage and loss of efficiency.