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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 is an incompressible medium, and the use of a hydrodrome built into the passenger seat will avoid shaking the passenger seats in the event of an airplane falling into a zone of strong turbulence. Chaotic movements of the aircraft will be extinguished by the hydraulic environment, that is, if the aircraft sharply swings down, then according to the laws of physics, the passenger in the seat must remain in the moment for the moment at the point from which the aircraft has deviated, and for a turn, at a sharp rise, The passenger will begin to squeeze into the chair. The two cases considered are rather private, however, taking into account the chaotic movement of the aircraft in turbulence, a strong vibration will be created, during which traumas can be caused by a person. Using the same hydrodrome, will allow to quench these fluctuations, thereby minimizing any possible harm, creating safe conditions 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 the turbulent motion of air masses, the disorder of the velocity field in time and in space, the presence of inhomogeneities or turbulent vortices that affect the behavior of the aircraft are characteristic. A spectrum of vortices of different sizes (scales) is created. The inverse of the scale is called the spatial frequency, just as the circular frequency w in radio engineering is a reciprocal of the oscillation period. The distribution of turbulent energy over spatial frequencies, which is called the turbulence spectrum, is its rather complete characteristic. The quantity e, as a dimensional parameter of the turbulence spectrum, characterizes its intensity.

The nature of turbulent motion in the atmosphere is such that the energy of large-scale vortices is transmitted to vortices of smaller scale - the vortices seem to be fractured. This continues until the whirlwinds become so small that their kinetic energy will go entirely to overcome the viscosity of the air and turn into heat. Such a process of turbulent motion proceeds continuously, while there is an energy replenishment of large-scale eddies from atmospheric energy sources associated with the temperature and pressure difference. The transformation of the kinetic energy of turbulence into heat is called the dissipation of the kinetic energy of turbulence (ДКЭТ). The value of e in its physical content is the rate at which the kinetic energy of turbulence of minimum scales is converted into heat. The higher in, the higher the intensity of turbulence.

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

The horizontal dimensions of the TIAN vary within fairly large limits, especially in the troposphere, reaching in some cases several hundred kilometers. However, for 80% of cases in the upper troposphere of temperate latitudes, the length of turbulent zones does not exceed 140 km. In the stratosphere, the TIAN zones have considerably smaller horizontal dimensions. At an altitude of 10-20 km, the horizontal length of the turbulent zones (80% of cases) in the temperate latitudes of the CIS territory is less than 80 km, and in the lower stratosphere over the USA - up to 40 km. This means that when a supersonic aircraft crosses at the cruising mode of the TIAN zones, the bolt is 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.

Thickness of TIAN zones, as well as horizontal dimensions, fluctuates in significant ranges depending on the latitude, altitude of location and aerosynoptic conditions. In the middle and high latitudes of the CIS (85-90% of cases), the thickness of the turbulent zones in the troposphere does not exceed 1000 m, and in the stratosphere it is 350 m., Hence, the TIAN zones have a pronounced spatial anisotropy. These are planar formations, the coefficient of spatial anisotropy of which (the ratio of the thickness of the turbulent zone to its horizontal length) at 80-percent integral repeatability is for the upper troposphere of medium latitudes.

Turbulence video 2

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