3. An experimental 4-stroke petrol engine having the following data is fitted with a single jet carburettor: Capacity of the engine = 1489 cc Speed at which max power is delivered = 4200 rpm The volumetric efficiency (at above speed) = 75% The air-fuel ratio = 13:1 Theoretical air speed at throat (at max power) = 85 m/s The coefficient of discharge of venturi= 0.82 The coefficient of discharge of the main fuel jet = 0.65 The density of petrol = 740 kg/m Level of petrol surface below the nozzle jet = 6 mm Atmospheric pressure and temperature = 1.013 bar; 20C Emulsion tube diameter = 40% of venturi throat diameter The properties of air are Cp-1005 J/kg.K, R=287 J/kg.K, y=1.4, [1 bar = 105 N/m] Calculate: (i) (ii) (iii) the venturi throat diameter when air is considered incompressible the venturi throat diameter when air is considered compressible the diameter of the main fuel jet

3. An experimental 4-stroke petrol engine having the following data is fitted with a single jet carburettor: Capacity of the engine =1489cc Speed at which max power is delivered =4200rpm The volumetric efficiency (at above speed) =75% The air-fuel ratio =13:1 Theoretical air speed at throat (at max power) =85m/s The coefficient of discharge of venturi =0.82 The coefficient of discharge of the main fuel jet =0.65 The density of petrol =740kg/m3 Level of petrol surface below the nozzle jet =6mm Atmospheric pressure and temperature =1.013 bar; 20C Emulsion tube diameter =40% of venturi throat diameter The properties of air are Cp=1005J/kgK,R=287J/kgK,=1.4,[1 bar =105N/m2] Calculate: (i) the venturi throat diameter when air is considered incompressible (ii) the venturi throat diameter when air is considered compressible (iii) the diameter of the main fuel jet