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Unformatted text preview: Maximum gas pressure = 5 N/mm2 ; Indicated
mean effective pressure = 0.75 N/mm2 ; Mechanical efficiency = 80% ; Fuel consumption = 0.15 kg
per brake power per hour ; Higher calorific value of fuel = 42 × 103 kJ/kg ; Speed = 2000 r.p.m.
Any other data required for the design may be assumed.
Solution. Given : D = 100 mm ; L = 125 mm = 0.125 m ; p = 5 N/mm2 ; pm = 0.75 N/mm2;
ηm = 80% = 0.8 ; m = 0.15 kg / BP / h = 41.7 × 10–6 kg / BP / s; HCV = 42 × 103 kJ / kg ;
N = 2000 r.p.m.
The dimensions for various components of the piston are determined as follows :
1. Piston head or crown
The thickness of the piston head or crown is determined on the basis of strength as well as on the
basis of heat dissipation and the larger of the two values is adopted. Internal Combustion Engine Parts n 1141 We know that the thickness of piston head on the basis of strength,
tH = 3 p . D2
16 σt 3 × 5 (100) 2
= 15.7 say 16 mm
16 × 38
...(Taking σt for cast iron = 38 MPa = 38 N/mm2) Since the engine is a four stroke engine, therefore, the number of working strokes per minut...
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- Spring '11