Клименко, М. О. та Кухнюк, О. М. та Klуmenko, M. O. та Kukhniuk, O. M. (2019) ДОСЛІДЖЕННЯ ПАРАМЕТРА ЗАКРУТКИ В ГЕНЕРОВАНИХ ВИХРОВИХ ПОВІТРЯНИХ ПОТОКАХ. Вісник Національного університету водного господарства та природокористування (2(86)). с. 203-212.

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Анотація

Наведені результати є продовженням досліджень, що присвячені генерації вихрових потоків (торнадо). В результаті реалізації планованого експерименту, отримано математичну модель, що дає змогу прогнозувати зміну вертикальних і горизонтальних складових швидкості руху вихрових потоків (в межах факторів варіювання).

Title in English

INVESTIGATION OF THE TWIST PARAMETER IN GENERATED VORTEX AIR FLOWS

English abstract

Vortical atmospheric conditions are one of the most common types of motion, both in nature and in modern technical devices. Such flows are characterized by movement in the region of centrifugal forces and fundamentally different from the axial flows of gas by such parameters as: axial, rotational, radial velocity, gradients of static and full pressure, turbulence, etc. Theoretical and experimental studies of vortices indicate that their parameters to a large extent depend on the intensity (parameter) of the twist. Here is the simplest expression for the spin parameter S. S = Uφ / Uz where: Uφ – azimuthal (tangential velocity), Uz – axial (vertical velocity). The physical meaning of this expression is as follows: If S << 1 – small azimuthal velocities and large axial velocities – then the vortex of the vortex is small; otherwise, S >> 1 (large azimuthal velocities, small axial velocities), the spin of the flow is large. As a rule, in practice, it is assumed that at S  1 and more the twist of the flow is large. Experiments were carried out in a mode determined by the matrix of the three-factor plan of Box-Behnken (Table 1). The following factors, variations (studies) were selected: Engine revolutions – Vd; Angle of guides (creating vortex air movement in the installation) at the bottom of the installation – α; The area of opening of air damper (for adjusting the volume of air pumped through the installation) – Sz. Selected variables of the planned experiment have different degrees of influence on the studied change in the vortex of the vortex stream. Moreover, the greatest effect was observed only with certain combinations. For example, the constant effect of increasing the spin of ascending air flow is observed at the mean values of the rotational speed of the installation ( =1800…2200). The influence of air guides (α0) played a minor role in relation to other selected variation factors, which ensure the degree of twisting of air flows, and in turn revealed the minimum optimum of air twist at the values of the opening area of the damper Sz = 0,25. The small values of the spin parameter obtained in this experiment indicate a significant excess of vertical component velocities above the tangential components in the aerial spin flows created in the experimental installation. In turn, the high values of the axial (vertical) component obtained in experiments confirm the similar results from other researchers can say that the laboratory-generated vortex strictures are very similar to the actual structure of air vents and can explain the effects of bracketing with the next transfer of heavy items during real tornadoes.

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