Key points of the power stroke of an aviation piston engine

The key points of the power stroke of an aviation piston engine are as follows:

1. Ignite with the spark plug

Ignition timing: At the end of the compression stroke, when the piston approaches the top dead center, the spark plug generates an electric spark through high voltage.

Ignition purpose: To ignite the highly compressed mixture (a mixture of gasoline and air) in the cylinder.

2. Combustion process

Mixture combustion: After the spark plug ignites, the mixture burns rapidly, generating high-temperature and high-pressure gas.

Burning speed: The burning process is extremely rapid, with a short burning time of approximately 0.015 seconds, but the speed is very fast, reaching up to 30 meters per second.

Temperature and pressure changes: During the combustion process, the temperature and pressure of the gas in the cylinder rise sharply, reaching 2000 to 2500°C, and the pressure can increase to 60 to 75 atmospheres.

3. Piston movement

Piston downward movement: Under the action of gas, the piston is subjected to a huge impact force and rapidly moves downward to the dead center (the lowest point of the piston's movement in the cylinder).

Energy conversion: The downward movement of the piston converts the internal energy of the gas into mechanical energy, driving the connecting rod and crankshaft to rotate.

4. The connecting rod and crankshaft rotate

The function of the connecting rod: The connecting rod connects the piston and the crankshaft, converting the linear motion of the piston into the rotational motion of the crankshaft.

Crankshaft rotation: The rotational motion of the crankshaft drives the propeller to rotate through the propeller reducer, generating a pushing (pulling) force that propels the aircraft forward.

5. The importance of power stroke

The sole power stroke: In a four-stroke engine, the power stroke is the only stroke that enables the engine to operate and generate power.

Energy output: During the power stroke, the engine converts the chemical energy of the fuel into mechanical energy, providing power for the aircraft's flight.

6. Combustion efficiency and emissions

Combustion efficiency: The combustion efficiency of the power stroke directly affects the performance and economy of the engine. A good combustion process can enhance the power output and fuel utilization rate of an engine.

Emission impact: The exhaust gas generated during the combustion process is discharged from the cylinder through the exhaust stroke. The level of combustion efficiency also affects the quality of exhaust gas emissions. An efficient combustion process helps to reduce the emission of harmful gases.

7. The role of the auxiliary system

Ignition system: The performance and reliability of the ignition system are crucial for the smooth operation of the power stroke. A reliable ignition system can ensure that the spark plugs generate sufficient electric sparks at the right time to ignite the mixture.

Fuel system: The performance of the fuel system and the proportion of the mixture will also affect the combustion efficiency of the power stroke. An appropriate mixture ratio and good fuel atomization effect can help improve combustion efficiency.

8. Special circumstances

Detonation phenomenon: In some cases, if the mixture burns too fast or too vigorously, detonation may occur. Knocking can cause damage to the engine, so measures such as adjusting the ignition advance Angle and the mixture ratio are needed to prevent knocking from occurring.

In conclusion, the power stroke of an aviation piston engine is a crucial step in the engine's working cycle. It converts the internal energy of the gas into mechanical energy through the ignition of the spark plug and the combustion process of the mixture, thereby propelling the aircraft forward. The combustion efficiency of the power stroke, the performance and reliability of the ignition system, and other factors will all affect the performance and economy of the engine.