The GATE Grind

GATE 2018 ME (ME2) – Question 21

Thermal Engineering Applications · Turbomachinery: turbines, compressors, pumps · 1 mark · Multiple choice

Select the correct statement for a 50% reaction stage in a steam turbine.

  1. The rotor blade is symmetric.
  2. The stator blade is symmetric.
  3. The absolute inlet flow angle equals the absolute exit flow angle.
  4. The absolute exit flow angle equals the inlet angle of the rotor blade.

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (D) The absolute exit flow angle equals the inlet angle of the rotor blade.

Explanation

For the conventional 50% reaction stage at constant axial velocity, inlet and outlet velocity triangles are symmetric: absolute exit flow angle equals the rotor-relative inlet angle. Hence **D**. Triangle symmetry does not imply either individual blade profile is geometrically symmetric.