In a reaction turbine, the fixed blades and moving blades are of the same shape but reversed in direction. The angle of the discharging tip is 20°. The mean blade velocity is 200 m/s. The axial velocity of flow of steam is half of the mean blade velocity. Determine the inlet angles of blades.

Correct Answer: 53°
Given, Cbl = 200 m/s, α = 20° Cf1 = Cf2 = 0.5(Cbl) = 0.5(200) = 100 m/s Steps of constructioSelect a suitable scale and draw a line LM to represent Cbl (= 200 m/s). Draw line 1-2 parallel to line LM at a distance corresponding to 100 m/s from line LM. At M, draw a line at an angle of 20° (α) to cut the line 1-2 at S. Join LS. Produce L to meet the perpendicular drawn from S at P. Thus inlet triangle is completed. By measurement: θ = 53° (= Ф).