ME6404& THERMAL ENGINEERINGClass /Sem: Duration: Date : Max. Marks

PART-A 5 X 2 = 101. Define the critical pressure ratio? (NOV/DEC 2013)2. What are the factor which contribute to knocking in SI engine? [MAY2012]3. What is the effect of super saturated flow in a nozzle?[NOV/DEC 2012]4. State the relation between velocity of steam and heat of a steam nozzle[APR-MAY2012]5. Define nozzle efficiency .(NOV/DEC2013)

PART-B 40Marks

6. a) Following data relates to single cylinder, 4stroke diesel engine: area of indicator diagram=3cm2, length of diagram=4cm,spring constant=10bar/cm, speed of engine=400rpm,load on brake=380N, spring balance reading=50N,diameter of brake drum=120cm,fuel consumption=2.8kg/h, CV=42000kj/kg, diameter of cylinder=16cm, stroke of piston=20cm, Calculate i) frictional power of the engine ii) mechanical efficiency iii) brake thermal efficiency and iv) brake mean effective pressure[NOV/DEC 10] (16) (or) b) The following details were noted in a test on a four cylinder, four stroke engine, diameter=100mm, stroke=120mm speed of the engine=1600rpm, fuel consumption=0.2Kg/min, fuel calorific value=44,000 KJ/Kg, difference in tension on either side of the brake pulley=40kgf, brake circumference is 300cm. If the mechanical efficiency is 80%, calculate i) brake thermal efficiency ii) Indicated thermal efficiency iii) indicated mean effective pressure and iv) brake specific fuel consumption [NOV/DEC 08] (16)

7. a) Derive the condition for maximum discharge and expression for maximum discharge in steam nozzle[NOV/DEC2013] (16) (or)b) Steam at a pressure of 10.5 bar and 0.95 dry is expanded through a convergent divergent nozzle and leaves it at a pressure of 0.85bar. If the steam flow process is isentropic and if the corresponding expansion index is 1.135 and having throat area 1.2cm2, find the ratio of cross sectional area at exit and throat for maximum discharge. Assume the flow is frictionless. [NOV/DEC 2013] (16)