Ε Semester engineers

A basic part of the cycle of an internal combustion engine is the supply of fresh air and removal of 1. e……………. gases. This is the gas exchange process. Scavenging is the removal of exhaust gases by blowing in fresh 2. a……………. . Charging is the filling of the engine cylinder with a supply or charge of fresh air ready for 3. com…………….. . With supercharging, a large mass of air is supplied to the cylinder by blowing it in under 4. p……………. . Modern engines make use of exhaust gas driven 5. t…………………… to supply pressurised fresh air for scavenging and supercharging. Both four-stroke and two- stroke engines may be pressure charged. Unlike the 4-stroke engine, a two- stroke diesel engine does not use the piston to push out the exhaust gas. Instead, air enters the cylinder around bottom 6. d………….. centre and sweeps or scavenges the exhaust gas from the cylinder. Two-stroke engines with an exhaust valve mounted in the cylinder head are known as 7. Uni…………….. scavenged engines. This is because the flow of scavenging air is in one direction. Some two-stroke engines do not have 8. v………….. ; as well as scavenge ports in the cylinder liner, they are fitted with exhaust ports located just above the scavenge ports. As the piston uncovers the exhaust ports on the 9. P…………….. stroke, the exhaust gas starts to leave the cylinder. When the scavenge ports are uncovered, scavenge air loops around the cylinder and pushes the 10. Rem………. exhaust gas out of the cylinder. This type of engine is known as a loop scavenged engine.