What is a typical consequence if turbine blade clearance is excessive?

• A. Reduced efficiency and stability
• B. Increased efficiency
• C. No effect
• D. Lower weight

Answer: (A)

Excessive blade clearance allows more high-pressure gas to leak over the tips as it moves through the turbine. That tip leakage wastes energy because less of the gas’s pressure energy is transferred to the blade to produce work. The result is lower overall efficiency and, because the flow around the blades becomes less uniform and more prone to disturbance, reduced stability of operation. The other options don’t fit: increasing efficiency would not come from a larger clearance, there is a clear effect on performance, and blade clearance does not directly affect weight.