LO2 Flashcards
Describe the main components of a gas turbine and their respective functions.
The main components of a gas turbine include the rotor, casings, fixed blades, seals, combustion chamber, and exhaust. The rotor rotates and drives the compressor and generator. Casings enclose the rotor and other internal components. Fixed blades guide airflow through the turbine. Seals prevent air or gas leakage. The combustion chamber mixes fuel with compressed air and ignites it. The exhaust expels high-temperature gases.
How does a gas turbine convert fuel into mechanical energy? Provide a step-by-step explanation.
Step 1: Air is drawn into the compressor and compressed.
Step 2: Compressed air enters the combustion chamber, where fuel is injected and ignited.
Step 3: The ignited fuel-air mixture expands rapidly, creating high-temperature, high-pressure gases.
Step 4: The high-pressure gases flow through the turbine, driving the turbine blades and rotor.
Step 5: The rotating rotor drives the compressor and generator, converting mechanical energy into electrical energy.
Identify and describe the primary components of a diesel engine and their roles in the combustion process.
The primary components of a diesel engine include the crankshaft, connecting rod, piston, cylinder head, exhaust, and fuel injector. The crankshaft converts reciprocating motion into rotational motion. The connecting rod transfers motion from the piston to the crankshaft. The piston compresses air and fuel, and the cylinder head houses the combustion chamber and valves. The exhaust expels combustion gases, and the fuel injector injects fuel into the combustion chamber.
Outline the four-stroke cycle of a diesel engine, including the specific actions of the piston and valves during each stroke.
The four-stroke cycle of a diesel engine includes the intake stroke, compression stroke, power stroke, and exhaust stroke. During the intake stroke, the piston moves downward, drawing air into the cylinder through the intake valve. In the compression stroke, the piston moves upward, compressing the air. During the power stroke, fuel is injected into the compressed air, and combustion occurs, driving the piston downward. In the exhaust stroke, the piston moves upward again, pushing the spent gases out through the exhaust valve.
Compare the power output of a diesel engine to that of a gas turbine for a similar application.
Diesel engines typically produce lower power output compared to gas turbines for a similar application. However, diesel engines offer advantages such as higher efficiency at partial loads, lower fuel consumption, and better fuel flexibility.
What factors influence the efficiency of a diesel engine, and how can these factors be optimized?
Factors influencing diesel engine efficiency include compression ratio, combustion chamber design, fuel injection timing, and exhaust gas recirculation. These factors can be optimized through engine design improvements, advanced fuel injection systems, and electronic engine management systems.
Describe the role of the crankshaft in a diesel engine and its relationship to piston movement.
The crankshaft in a diesel engine converts the reciprocating motion of the pistons into rotational motion, which drives external loads such as vehicle wheels or generators. The pistons are connected to the crankshaft via connecting rods, and as the pistons move up and down within the cylinders, they transmit force to the crankshaft, causing it to rotate.
Discuss the advantages and disadvantages of diesel engines compared to other types of internal combustion engines.
Advantages of diesel engines include higher fuel efficiency, greater torque output, and longer lifespan compared to gasoline engines. However, diesel engines tend to produce higher emissions of nitrogen oxides (NOx) and particulate matter (PM) and require more complex emissions control systems. Additionally, diesel fuel can be more expensive than gasoline in some regions.
