PRINCIPLES OF NAVAL ENGINEERING 



SEA WATER INLET 



EXHAUST 



ffl 



ID 

 IB 

 iO 



INLET PIPE 



FLEXIBLE 

 PIPE 



EXHAUST 

 SILENCER 



^:*P> EXHAUST AND 



WATER 

 JACKET 



EXHAUST 

 MAN! FOLD 



AIR INTAKE 

 PORTS 



SEA WATER 

 OUTLET 



WATER LINE 



OVERBOARD 

 DISCHARGE 



TAKE 

 SILENCER 



AIR BOX 



AIR SCREEN 



75.151X 



Figure 22-20.-Air systems of a 2-stroke cycle engine. 



is called scavenge ( or scavenging ) air and the 

 ports through which it enters are called scavenge 

 ports . 



The process of scavenging must be accom- 

 plished in a relatively short portion of the oper- 

 ating cycle; however, the duration of the process 



differs in 2- and 4-stroke cycle engines. In a 

 2-stroke cycle engine, the process takes place 

 during the later part of the downstroke (expan- 

 sion) and the early part of the upstroke (com- 

 pression). Ina4-stroke cycle engine, scavenging 

 takes place when the piston is nearing and 



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