Thermal Engineering — Summer 2018

Describe the governing of steam turbine? State different methods of governing and explain the throttle control governing of steam turbine with neat sketch.

Write short note on following:-

Back pressure turbine (ii) Ramjet engine

Derive an equation of critical pressure ratio of nozzle and explain its significance. Calculate its value for superheated steam.

Write a short note on- various requirements of a typical combustion chamber of the gas turbine plant.

State and explain in brief the different sources of losses in steam turbines.

Explain super saturated flow of steam through a nozzle and plot the process on h- s diagram. Also explain in brief the significance of Wilson’s line.

Define the term “Degree of Reaction”. Explain Parson’s reaction turbine.

Explain the effect of varying the back pressure in convergent divergent nozzle and state when maximum flow occurs in the nozzle.

Enlist the various methods of attachment of blades to turbine rotor. Explain any one of them with neat sketch.

Enlist different methods used to improve efficiency and specific work output of open cycle gas turbine plant and explain any two with neat sketches and with T-Sdiagram.

Derive a general expression for the blade efficiency of a simple impulse turbine with a single row wheel. Also discuss the influence of the speed ratio on the efficiency of the system.

Explain the working principle of Turboprop engine with neat diagram and state its merits and demerits.

For maximum work out put in actual Brayton Cycle, derive an expression of optimum pressure ratio.

Describe the term, “compounding of steam turbine” and explain pressure compounded impulse turbine with necessary diagrams.

Air enters the compressor of a simple gas turbine unit at 1 bar and 300 0K. The turbine inlet temperature is limited to 950 0K. The gases expand down to atmospheric pressure. Compare the thermal efficiency and the work ratio of the ideal cycle when the pressure ratio is 5 and 8.1

Explain in brief “Back Pressure Steam Turbine” with neat sketch and h-s diagram.

In a 2-row velocity compounded impulse turbine, the steam leaves the nozzle at 800 m/s. The moving blade tip angles are 300 and the blade velocity coefficients for fixed and moving blades are 0.9. Estimate the blade speed when the nozzle angle is 160 and the discharge is axial.