Mechanical Engineering:: Steam Nozzles and Turbines

The exhaust valve in a four stroke cycle petrol engine

A. opens at 50ο before bottom dead centre and closes at 15ο after top dead centre
B. opens at bottom dead centre and closes at top dead centre
C opens at 50ο after bottom dead centre and closes at 15° before top dead centre
D. may open and close anywhere

In a reaction turbine, when steam flows through the fixed blades,

A. pressure increases while velocity decreases
B. pressure decreases while velocity increases
C pressure and velocity both decreases
D. pressure and velocity both increases

The efficiency of steam turbines may be improved by

A. reheating of steam B. regenerative feed heating
C. binary vapour plant D. any one of these

The ratio of the useful heat drop to the isentropic heat drop is called

A. condenser efficiency B. nozzle efficiency
C. boiler efficiency D. vacuum efficiency

The difference of supersaturated temperature and saturation temperature at that pressure is called

A. degree of supersaturation B. degree of superheat
C. degree of undercooling D. none of these

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