Volodimir Karachun

The Additional Error of Inertial Sensors Induced by Hypersonic Flight Conditions

The emergence of hypersonic technology pose a new challenge for inertial navigation sensors, widely used in aerospace industry. The main problems are: extremely high temperatures, vibration of the fuselage, penetrating acoustic radiation and shock N-waves. The nature of the additional errors of the gyroscopic inertial sensor with hydrostatic suspension components under operating conditions generated by forced precession of the movable part of the suspension due to diffraction phenomena in acoustic fields is explained. The cause of the disturbing moments in the form of the Coriolis inertia forces during the transition of the suspension surface into the category of impedance is revealed. The boundaries of occurrence of the features on the resonance wave match are described. The values of the “false” angular velocity as a result of the elastic-stress state of suspension in the acoustic fields are determined.

Analysis of the technical possibility of submarine camouflage from direction finding means

The submarines studied in this work have an indisputable advantage, consisting in increased concealment, which allows them to concentrate in strategically important areas of the water area with attack means containing a combat unit of various composition and power. Concealment of the submarines significantly increases the danger of hitting critical infrastructures of states of medium and small area, even without their own water area. Submarines, in addition to the marked advantage, have obvious disadvantages, which include «blindness» and «noisiness». Therefore, when solving tactical and strategic tasks of defense significance, it is necessary to take into account the need to eliminate these disadvantages. One of the variants of the technical solution is presented for providing the submarine camouflage from the direction finding equipment with the help of hydroacoustic stations – underkeel, drop, towed. An analytical model of the technical effect is constructed to achieve limited visibility of the submarine outside the zone of geometric resonance. The effectiveness degree of submarine camouflage is analyzed in the case of the onset of a resonant situation in the enclosing module - wave coincidence. The preconditions for the onset of resonance are formulated under the condition that a large wave size of the outer shell of the enclosing module is provided. The content of aberration phenomenon irradiated by the outer shell of sound waves into the fluid of the inter-shell space is revealed. Semi-detailed laboratory studies of the submarine model allow using ultrasonic technologies to ensure the concealment of the submarine in the absence of its own propulsion by means of a two-shell module separated by a liquid and artificially irradiated with ultrasound. At the same time, the theoretical prerequisites for increasing the effectiveness of submarine camouflage using resonant appearance in the form of wave coincidence in a laboratory unit confirms the correctness of the initial technical solutions. This allows to evaluate step-by-step the requirements of high camouflage efficiency: – large wave size of the shell module; – creation of caustic zones in the inter-shell space, which acts as a enclosing surface from the direction finding equipment; – ensuring of the geometric resonance of the outer shell to form its «acoustic transparency»; – creation of a zone of increased energy in the form of turbulence of the inter-shell liquid.

Reproducing of security and limited visibility of fire weapons of defence line from aerial reconnaissance

The object of the research is a process of an elastic interaction of ultrasound beam with a cylindrical module in the form of two circular shells with same length coaxially connected to their ends. Sealed gap between two circular shells is filled with fluid. Outside irradiation by the ultrasonic beam affects the properties of the module, including the emergence of local characteristics of the outer shell, and to change energy state of liquid-static gap between shells. It is great interest in the applied use of these changes for echolocation tasks in terms of artificial formation of «acoustic transparency» situation. The following research methods are used: methods of construction of fencing structures, methods of radiation acoustics and methods of hydroacoustics. The features of the studied mechanical system are revealed at the resonant level of wave coincidence. The content of aberration phenomena of sound waves that are emitted into the liquid is defined and surface barriers in the form of caustic zone with a high degree of turbulence and energy state is built. Economic conditions for use of ultrasound beam energy to the desired «acoustic transparency» of the outer shell at low and below the limit frequencies are outlined. Comparative analysis of the object photos inside the inner shell for the original time and during irradiation allows qualitatively assess change clear outline of the object to blurred patch that was the aim of research. Opportunities for quality improvement of effect are related to the choice of physical and chemical, in particular, optical properties of the liquid. Thus, caustic zone, which is formed artificially by ultrasound, will block echolocation means and make invisible military equipment of open field fortifications.

Забезпечення скритної дислокації танка у фортифікаційних спорудах відкритого типу

Results of laboratory tests of the mock battle tank from the means of air reconnaissance are analyzed. It is proved that the use of artificial forming for fencing surfaces based on the principles of building of caustic zones caustic with adjustable wave coincidence allows achieving full masking of tank on the resonance level of ultrasonic irradiation of external shell-like tunnel with partial immersion of its bottom into a soil

Acoustic Radiation Energy Focus in a Shell with Liquid

When the geometric dimensions of the cylindrical housing are much greater than the sound wavelength, the excitation zones. There is thus a focusing of penetrating acoustic radiation energy, which takes the form of a caustic surface. This results in a sharp concentration of the sound wave energy inside a liquid static part of the suspension, accompanied by a significant increase in the sound pressure level. Upon housing irradiation with a wide enough sound beam, which, by the way, is observed under operating conditions in the form of a reverberant space, the coincidence resonance may occur for both transverse and circumferential waves. Furthermore, the liquid static parts may also have the radial bands of sound radiation energy concentration as a result of interference phenomena.