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HYDRODYNAMICS AND ACOUSTICS
2021 ◊ Volume 2 (92) ◊ Issue 1 ◊ p. 94-106
Yu. N. Savchenko*, Yu. D. Vlasenko*, G. Yu. Savchenko*
* Institute of Hydromechanics of NAS of Ukraine, Kyiv, Ukraine
Reducing the intensity of hydrodynamic fields generated by moving objects
Gidrodin. akust. 2021, 2(1):94-106
TEXT LANGUAGE: Ukrainian
ABSTRACT
In some cases, the reduction of generated wave disturbances is advisable in the motion of water vehicles. This can be achieved, for example, due to the interference of surface waves with a properly designed hull system of a multihull vessel with a small waterline area. Another way of implementing undisturbed motion is to use a hull with an internal channel. the problem of interaction between the propulsor and the ship's hull is also important in this context. This article considers possible schemes for organizing the undisturbed motion when the field of surface waves from the body motion is absent outside a limited area around it. The principal possibility of organizing such a regime in uniform straight-line motion of a body with a special surface shape in a liquid is confirmed. The schemes with the channel in the body and the propulsor in the main flow are considered in detail. The possibility of suppressing the slowly decaying component of disturbances when placing the propulsors in the main flow is shown. The results of mathematical modeling indicate the possibility of a significant, two to three orders reduction of disturbances in comparison with traditional vehicle designs. The task of minimizing surface disturbances is not always equivalent to reducing resistance. Therefore, the energy expenditures required to overcome the internal friction in the channel and the external body surface were estimated. The analytical expressions are given for calculating the necessary velocity and pressure differences on the surfaces bounding the control volume. The results of experiments with the models moving on the water surface confirm the possibility of eliminating systems of accompanying surface waves. The specifics of the experimental sample design were the presence of an internal channel for the flowing liquid. At the same time, the contours of the hull according to the "Jonka" design were used. The role of a working engine in the organization of an undisturbed motion mode is demonstrated.
KEY WORDS
undisturbed motion, wave drag, multihull vessel, internal channel, propulsor