🔍 Key Concepts

• Reaction turbines and how pressure/velocity change across the blades • How tip clearance between blade tips and casing affects efficiency and leakage • Effect of blade geometry (especially at the tip) on leakage vs. strength/rigidity

💭 Think About

• Ask yourself: What happens if the gap between blade tip and casing is too large in a reaction turbine? Which option directly relates to that problem? • Think about which option is most clearly about fluid flow control rather than mechanical support or thermal growth. • Consider whether "thin" at the tip would more likely help with flow leakage, mechanical strength, or expansion space.

✅ Before You Answer

• Identify which choice is specifically about fluid escaping around the blade tips rather than through the designed flow path. • Distinguish between axial expansion (along the shaft) and radial clearance (radius from shaft to casing). Which one is most influenced by shaping the blade tip? • Ask: Does making the tip thinner primarily aim to boost strength and rigidity, or to control how the working fluid behaves near the casing?