What is the white smoke behind a plane? How did it come about?

The aircraft consumes a large amount of fuel when flying, and the water vapor and part of the heat generated are discharged out of the aircraft with the exhaust gas, enter the atmosphere, and quickly mix with the surrounding air to form contrails. The process of its formation is different from the dew, frost and clouds in the air that people commonly see on the ground. The exhaust gases emitted by the aircraft at high altitudes are mixed with the ambient air, and the saturation of this mixture depends on the net effect of both heat and water vapour increases.

When the humidification effect prevails and exceeds a given threshold, contrails are formed; When the heat gain effect is dominant, no condensation occurs and no condensation trails appear. Since the heating and humidification effects of the exhaust gas are certain, whether there will be condensation in the mixture will depend on the temperature, humidity and atmospheric pressure of the ambient air itself. In short, high ambient air temperatures are not conducive to the formation of contrails, and aircraft contrails are only possible when the ambient temperature is quite low (usually below 40).

According to the relevant data, when the aircraft wake appears, the air temperature is mostly 41 60, accounting for about 86 of the aircraft wake, if the air temperature is higher than 40 or lower than 60, the aircraft wake phenomenon is rarely occur. The seasonal variation in the height of the aircraft's wake is not obvious, and in general, it occurs more often in the winter half of the year than in the summer half of the year. The thickness of the wake layer averages 1 2 km, and the lower limit height is the lowest in winter and the highest in summer.

In thicker aircraft contrails, the length and concentration of wakes formed at different altitudes are also different. Usually at the bottom of it is a short and light-concentrated trail, which gradually lengthens and thickens upwards, and when it reaches a certain height, it becomes an intermittent and light-toned trail again. A special cloud formed by the exhaust gases from the engines of the aircraft during flight mixed with the surrounding air.

It generally occurs in the air layer with air temperatures below -40 degrees Celsius and suitable humidity conditions. The wake of the aircraft has no effect on the flight, but the whereabouts are exposed, which has a certain effect on the combat operations of the aviation.

This is what people usually call "airplane smoke", but in fact, it is a special cloud formed by the condensation of water vapor in the wake of the aircraft. Meteorologically known as aircraft wake. How did it come to be?

According to the cause, aircraft wake is divided into three types: exhaust gas wake, convective wake, and aerodynamic wake. Exhaust gas trails can be divided into two types: exhaust gas condensation trails and exhaust gas evaporation trails, and the common aircraft trails are mostly exhaust gas condensation trails. After the airplane, the engine spews out a large amount of water vapor of high-temperature gas, if the ambient temperature is very low (below 40), these high-temperature and high-humidity gases quickly mix with the surrounding air, the temperature drops rapidly, the humidity increases sharply, and then condenses to produce the aircraft wake, which is completely different from the smoke screen cast in the air show to increase the effect.

The formation of the wake of the aircraft, in addition to being related to the temperature of the surrounding atmosphere, depends on the temperature at the flight altitude. Experience has shown that aircraft wake can occur when the air temperature is above 40 60 and the humidity is above 40, or above 60 near the tropopause. Exhaust gas wakes mostly occur at altitudes above 11 13 kilometers above the ground.

Why does a white smoke form when an airplane flies in the sky?

byAircraft enginesDifferent caused, if it is a propeller aircraft is completely absent, if it isJetsAbsolutely, with current technology, the white smoke behind the tail cannot be eliminated for the time being, which is called the white gas phenomenon.

The cross-section of the wing of an aircraft is generally rounded and blunt at the front and sharp at the rear, with an arched upper surface and a flat lower surface. When equal mass air passes through both the upper and lower surfaces of the wing, different flow velocities are formed above and below the wing. The velocity of air passing through the upper surface of the wing is high and the pressure is small; When passing through the lower surface, the flow velocity is small and the pressure is strong, so the aircraft will have an upward resultant force, that is, the upward lift, due to the existence of lift, so that the aircraft can leave the ground and fly in the air.

The faster the aircraft flies and the larger the wing area, the greater the lift generated.

The direction of gravity is opposite to lift, and it is subject to the gravitational pull of the earth.

The gravity of the force is affected by the weight of the aircraft itself and the amount of fuel it carries. The pulling force causes the aircraft to fly forward in the air, and the power of the engine determines the amount of pulling force. Engine output.

The greater the thrust, the more thrust is generated and the faster the aircraft will fly. When the aircraft is in the air, it is hindered by atmospheric molecules in the air, and this obstacle forms a drag force that is opposite to the direction of the pulling force, limiting the flight speed of the aircraft.

The white smoke behind an airplane flying in the sky is a visible wake formed by concentrated water vapor expelled from an airplane's engine. As the exhaust fumes from the hot engine are cooled in the air, they can condense to form a cloud of tiny water droplets.

If the air temperature is low enough, the airplane cloud may also be made up of tiny ice crystals. The wingtip vortex dragged from the tip of the wing or flaps is sometimes partially visible due to condensation of water vapor in the core of the vortex. Each whirlpool is a large swirling expanse of air, and the air pressure in the center of the whirlpool is very low.

This wingtip vortex has no correlation with the exhaust fumes from the engine, and the wingtip vortex is sometimes referred to as a steam wake.

1.White smoke is the exhaust fumes produced by jet engines.

2.Only jet engines show white smoke. In general, the long "white smoke" behind a jet is due to the formation of water and carbon dioxide after the fuel is burned inside the engine.

Since the temperature at high altitude is very low, it condenses into a large number of small water droplets, which are suspended in the air and appear as a white smoke from a distance.

There are many reasons for white smoke, mainly in the following aspects.

1) The engine temperature is too low. Some diesel fuel turns into oil vapor when it is not burned, and is discharged from the exhaust pipe with the exhaust gas, emitting white smoke.

2) There is water in the oil supply system. There is water in the fuel or combustion chamber, and the water is heated into water vapor by the heat released by combustion in the cylinder, which is discharged from the exhaust pipe to form white smoke.

3) Injection time is too late. Due to the late injection time, the temperature of the cylinder has dropped during the fuel injection, and part of the diesel fuel has not been burned into oil vapor, emitting white smoke.

4) Poor atomization of fuel injectors. Poor atomization leads to incomplete combustion of diesel, and the high-temperature exhaust gas discharged from the normal working cylinder merges in the exhaust pipe, resulting in white smoke.

5) The cylinder pressure is too low. Some diesel fuel turns into oil vapor without combustion, so white smoke is emitted from the exhaust pipe.