1) Steam at 15 bar and 350 degrees C is expanded through a 50% reaction turbine to a pressure of 0.14 bar. The stage efficiency is 80% for each stage and the reheat factor is 1.05. The expansion is to be carried out in 10 stages and the required power is 6000 kW. Calculate the steam flow required, assuming that the stages all develop the same work. At one stage the pressure is 1 bar (saturated vapour) and the blade speed ratio is 0.77. If the blade height is 1/20 of the blade mean diameter, calculate the value of the mean blade diameter and the rotor speed.
2) A 50% reaction turbine expands 34000 kg/hr of steam from 20 bar, 400 degrees C to a pressure of 0.2 bar. The turbine is designed such that the steam leaving is just dry saturated. The reheat factor is 1.05 and the isentropic efficiency of each stage is the same throughout. There are 14 stages and the enthalpy drop is the same in each. All blades have an exit angle of 22 degrees and the mean value of the blade speed ratio is 0.82. Calculate the stage efficiency, the diagram power, drum diameter and the blade height for the last row of blades. The turbine speed is 2400 rev/min.© BrainMass Inc. brainmass.com October 16, 2018, 4:49 pm ad1c9bdddf
Notations and assumptions:
[ ]* = total features (like p*, T*)
V1, V2 = absolute velocities
This complete solution includes step-by-step calculations and answers formatted in the attached Word document. The explanation is 855 words.
Turbomachinery: Reaction Turbines
Please help with the following problem.
Sketch the fully annotated velocity triangles for a Parsons turbine stage. Use your sketch to show that the specific work produced per stage is given as w_stage = (C_b)^2 [1 + 2(f/C_b)(cot(B_1))].
At a particular stage of a Parsons reaction turbine, the mean blade speed is 60 m/s and the steam specific volume v = 0.577 m3/kg. The fixed and moving blades at this stage have inlet angles of 30 degrees and exit angles of 20 degrees. Sketch the velocity triangles and find:
a) The axial velocity
b) The blade height for this stage if the blade height is 1/10 of the mean blade diameter and the steam mass flow is 13.5 kg/s
c) The stage power
d) The diagram efficiency