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Overcoming turbulence.
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Turbulence

Turbulence

 

To date, the turbulence is a very topical issue for the aircraft, with the man unfortunately can not control the chaotic swirl of wind flows. Usually, turbulence poses a serious danger to the aircraft, however, to a greater extent of any adverse effects on the aircraft manages to avoid, but often at the same time, passengers are suffering, get a number of injuries and injuries due to violent shaking of aircraft.

 

turbulence

Turbulence after.

Reduce the threat to life and health of passengers still can put into practice a very interesting idea, based on a number of laws of hydrodynamics. The idea is quite simple and consists in that the passenger seats available in the aircraft cabin should be provided with hydraulic dampers that will be triggered at the slightest fluctuations in passenger aircraft, thereby reducing inertia and eliminating hundreds of passengers from injury and possible injuries.

 

Schematic diagram of the operation of the damping passenger aviakresla

As is known, the liquid medium is incompressible, and the use of hydraulic damper built into the passenger seat, to avoid shaking passenger seats when the plane hit, even in severe turbulence. Chaotic motion of an aircraft would be extinguished hydraulic medium, ie if the plane sharply will swing down, according to the laws of physics, the passenger is in the chair, shall, within moments, to be at the point from which the aircraft has strayed, and vice versa, with a sharp rise, begin to press in the passenger seat. Two cases are considered more private, but given the chaotic movement of the aircraft in turbulence, will create a strong vibration in which a person may be injured. The use of hydraulic damper, allows to extinguish these vibrations, thereby minimizing any possible damage, creating a safe environment for passengers.

 

 

Among other things, from the current development, and there is another very interesting purpose - passenger seats, equipped with damping elements is extremely effective in the case of a forced or emergency landing, eg in case of failure the chassis when landing the aircraft on unprepared terrain, etc. Hypothetically, used chair will also help protect passengers in the case of the crash, but only in that situation, if you do not happen subsequent fire, explosion, etc.

Kostyuchenko Yuriy specifically for Avia.pro

 

Atmospheric Turbulence

The velocity of the air and hung there particles varies in space and time. Ordered and turbulent motion of air masses differ primarily scales. Large-scale movement is considered to be ordered, and small-scale - turbulent. Draw a clear line between them is impossible: it is conditional and depends on the tasks and methods of measurement.

For turbulent motion of air masses characterized by disorder of the velocity field in time and space, presence of turbulent eddies or irregularities affecting the behavior of the aircraft. Creates a variety of vortices of different sizes (scale). The reciprocal of the scale is called the spatial frequency, similarly as the angular frequency w in electronics is the reciprocal of the oscillation period. The distribution of turbulent energy of spatial frequencies, called spectrum of turbulence, it is sufficiently complete characterization. The value of e as the dimensional parameter of the spectrum of turbulence characterized by its intensity.

The nature of turbulent motion in the atmosphere is such that the energy is transferred to large-scale eddies smaller vortices - whirlwinds like a fraction. It lasts as long as the vortices become so small that their kinetic energy will go entirely to overcome the viscosity of the air and turn into heat. This process occurs continuously turbulent motion as is the completion of large-scale vortices energy from atmospheric sources of energy associated with the difference in temperature and pressure. The conversion of kinetic energy into heat is called turbulence turbulent kinetic energy dissipation (DKET). The value of e in its physical content is the rate at which heat is converted into kinetic energy of turbulence minimum scale. The more, the higher the turbulence intensity.

Turbulence 4545

Turbulence is not observed throughout the atmosphere simultaneously is not at all altitudes. It occurs under the influence of thermal and dynamic factors. Therefore, to distinguish between thermal and dynamic turbulence.

Thermal turbulence appears as a result of the uneven heating of the earth's surface and large vertical temperature gradients. This kind of turbulence is typical for the bottom half of the troposphere (up to 3-4 km). Its intensity depends on the season, time of day and atmospheric stability. Mostthe intensity observed in the afternoon in the warm season in the cold unstable air masses, as well as blurred pressure field - in the saddle and cyclones.

When thermal turbulence in the atmosphere appear as random and ordered upward and downward movement of the air, are cumulus and cumulonimbus broken, fashionable cumulus and cumulonimbus clouds.

Dynamic turbulence created by friction of moving air on rough terrain the earth's surface and heterogeneity of air flow velocity and direction.

The friction of air on the Earth's surface on the flat and hilly terrain gives rise to a dynamic turbulence mainly in the lower layer of the troposphere (up to 1-1,5 km). In mountainous terrain it can spread considerably higher (up to 7-9 km).

Dynamic turbulence occurs in the layers of the free atmosphere with great variability of wind and occurs more frequently where there is convergence or divergence of air flow, the curvature of their direction, as well as in areas of jet streams. It can also occur in the form of ascending and descending flows as a result of wave motion on the boundary of the inversion layer and isotherms. Its intensity depends on the rate of vertical and horizontal wind shear.

Although thermal and dynamic turbulence created by the action of various factors on the nature of the air currents, they may affect both separately and simultaneously, increasing the intensity of the turbulent state of the atmosphere.

Turbulence makes the heat transfer in the atmosphere, water vapor and particulate vertically gusty winds. Turbulent exchange significantly affect the conditions of formation, evolution and microstructure of clouds, rain and fog, which create a bad weather for flying.

Turbulence intensity is observed in clear and cloudy sky. Since it is one of the oblakoobrazuyuschih factors consider its physical characteristics in a clear sky ("turbulent field").

There are several types of turbulence in clear air:

  • 1) mechanical turbulence caused by the influence of the earth's surface irregularities on air currents and sometimes intensify its uneven heating;

  • 2) mountain waves, which are the origin of a particular form of the turbulence of the first kind (because of the specific impact on the aircraft flight mountain waves are discussed separately);

  • 3) turbulent jet flows;

  • 4) turbulence in the inner layers of the atmosphere for free.

Turbulence in the clear sky is dangerous for aviation weather events due to the surprise effect on the aircraft. Several accidents have occurred as a result of falling aircraft under a cloudless sky in the danger zone of turbulence.

Turbulence air flow in the clear sky due to the existence of layers in the atmosphere with significant vertical and horizontal gradients of wind speed and air temperature.

In the context of the emergence of resistant temperature stratification of CAT can be explained by the loss of stability (an increase in amplitude and subsequent destruction) gravitational or gravitational waves sliding (over the mountains - mountain waves) and the transfer of energy from the wave motions in turbulent.

In the troposphere, the probability of hitting the sun in of CAT is quite high, it depends on the latitude. In the middle and upper troposphere temperate latitudes, this parameter is about 10% total flying aircraft in the southern latitudes - 15-20%. In the stratosphere, the probability is much smaller and in the layer 10-20 km is about 1%.

Getting in the zone chan planes most often subjected to mild to moderate rough air, the cumulative frequency of which is in the troposphere 95%, and only 5% of cases there may be a strong buffeting.

Turbulence Video

Horizontal dimensions of CAT vary within wide limits, particularly in the troposphere, reaching in some cases, several hundred kilometers. However 80% of cases in the upper troposphere temperate latitudes length turbulent zones no more than 140 km. In the stratosphere, the zone of CAT have much smaller horizontal dimensions. At the height of 10-20 km length of the horizontal turbulent zones (80% of cases) in the temperate latitudes of the CIS is less than 80 km, and in the lower stratosphere over the United States - to 40 km. This means that at the intersection of a supersonic aircraft at cruising turbulence zones of CAT observed for several seconds or tens of seconds.

Zones of CAT can be continuous (solid) and in the form of individual cells with Slight fairly sharp boundaries. Solid areas of CAT have great repeatability.

The thickness of the zone of CAT, as well as horizontal dimensions vary over a considerable range depending on latitude, altitude location and synoptic conditions. In the middle and high latitudes of the CIS (85-90% of cases), the thickness of the turbulent zone in the troposphere does not exceed 1000 m, and in the stratosphere - 350 m., Hence the area of ​​CAT have expressed strong spatial anisotropy. This flat formation, the ratio of spatial anisotropy of which (the ratio of the thickness of the turbulent zone to its horizontal length) at 80-percent repeatability is integral to the upper troposphere middle latitudes.

Turbulence video 2

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