Answer to Question #305534 in Mechanical Engineering for Jefin Baby

Question

VTU QUESTION-Steam issuing from a nozzle to a De - Laval turbine with a velocity of 1000 m/s. The nozzle angle is 20, the mean blade speed is 400m/s. The blades are symmetrical. The mass flow rate is 1000 kg/hr, Friction factor is 0.8, Nozzle efficiency 0.95. Taking the scale of = 1:100, find the following Graphically: i) Blade angles iv) Power developed ii) Axial thrust v) Blade efficiency iii) Work done per kg of steam vi) Stage efficiency

Answer 1

Blade angles in De - Laval turbine

BEC = 90° (for maximum efficiency), and 61 - 62 (for the De Laval blade).

The fundamental principles of the De Laval Steam-Turbine are clearly shown in Fig. 1, Plate 81. It is a pure impact turbine, with a single turbine wheel, carrying one row of buckets, to which the steam is delivered in free jets at the highest possible velocity.

The axial thrust is the resultant force of all the axial forces (F) acting on the pump rotor.