JNTU B.Tech III THERMAL ENGINEERING II Previous Question Paper (May/June - 2019 - R13)

Name the methods adopted for improving the performance of the Rankine cycle.

How does friction in the system affect the expansion and compression processes in the working of Rankine cycle?

Differentiate the fire tube and water tube boiler.

Derive an expression for maximum mass flow through a convergent divergent nozzle when steam is expanded isentropically.

What is the difference between impulse and reaction blading.

Explain the working of a single stage impulse turbine with the help of sketch.

Is it always useful to have a regenerator in a gas turbine power cycle? Why?

Derive the expression for thermal efficiency of the simple gas turbine cycle.

What are the various propulsive devices for aircrafts and missiles?

How rockets are classified? What is the essential difference between rocket propulsion and turbojet propulsion?

Discuss the effects of steam pressure and steam temperature at inlet to the turbine on a Rankine cycle.

In an engine the dry volumetric analysis of the products was CO2 = 0.0527, O2 = 0.1338 and N2 = 0.8135. Assuming that fuel is a pure hydrocarbon and that it is completely burnt, estimate the ratio of carbon to hydrogen in the fuel by mass and the air fuel ratio by mass.

What is adiabatic flame temperature? How flame temperature can be calculated.

Steam at 15 bar and 300°C expands isentropically in a steam turbine till the temperature falls to 80°C. Find the condition of steam at the end of expansion process and the work done per kg of steam. If the steam flow rate is 10 kg/s, what power will be produced by the turbine?

Sketch and describe the operation of Cochran vertical boiler. What are its special features?

Why boiler mountings are installed? Explain the operation of fusible plug with the help of simple diagram.

Explain the effect of friction in nozzle flow with the help of h-s diagram.

A group of convergent-divergent nozzles are supplied with steam at a pressure of 2 N/m² and a temperature of 325°C. Supersaturated expansion according to the law PV^1.3 = constant occurs in the nozzle down to an exit pressure of 0.36 MN/m². Steam is supplied at the rate of 7.5 kg/s. Determine the required throat and exit areas.

A simple impulse turbine has one ring of moving blades running at 150 m/s, absolute velocity of steam at exit is 85 m/s at an angle 80° with the tangent of wheel, friction coefficient is 0.82, rate of steam flowing 2 Kg/s. Assuming the moving blades to be symmetrical, find the i) Blade angles ii) Nozzle angle iii) absolute velocity of steam at entrance and iv) power developed.

Describe construction of inlet and exit velocity triangles of simple impulse turbine.

Sketch and describe the operation of central flow surface condenser.

Show that for maximum diagram efficiency of a reaction turbine the blade speed ratio is equal to cos α, where α is the angle of absolute velocity at inlet.

Explain the stages of combustion in a gas turbine combustion chamber with a neat sketch.

Derive an expression for the specific net work output of a simple ideal gas turbine cycle in terms of temperature and pressure ratios. Also prove that r_opt = (T_max/T_min)^[γ/(2(γ-1))].

With a neat sketch and T-s diagram, explain the working of a turbojet engine.

A turbojet engine flying at a speed of 800 km/hr consumes air at 45 kg/s. Calculate i) jet exit velocity, change in enthalpy for the nozzle is 190 kJ/kg and velocity coefficient 0.95, ii) fuel flow and TSFC, air-fuel ratio 80:1, iii) thermal efficiency (CV 43890 kJ/kg), iv) propulsive and thrust power, v) propulsive and overall efficiency.

An aircraft turbojet engine is flying at altitude where ambient conditions are 0.07 bar and 1°C. Flight speed 800 kmph. Determine fuel consumption and TSFC, thrust 25000 N, Ram efficiency 95%, total pressure ratio 5:1, compressor efficiency 85%, turbine efficiency 90%. Consider isentropic nozzle. CV = 42 MJ/kg.

Describe the operation of ramjet engine.