INVESTIGATION OF THE VARIABILITY OF LOCAL ICE STRENGTH BY EXPOSURE TO THE SPECTRUM OF INFRARED RADIATION OF VARIOUS LENGTHS

The object of research is the interaction of the infrared radiation spectrum with ice. The work is aimed at determining this interaction in order to ensure the safe passage of the route by ice-class vessels independently or as part of a caravan during the winter navigation period, in the freezing waters of non-Arctic seas and rivers, as planned and without delays. To solve this problem, in the course of the study, similarity coefficients equal to those calculated were used, and temperature intervals were determined corresponding to the selected discrete intervals of ice thickness. The processing of laboratory test data was reduced to statistical analysis, the purpose of which was to determine the statistical characteristics of the studied quantities. As well as the establishment of correlation between the studied values and the assessment of the strength characteristics of low-supply ice. This is due to the aim of establishing regressive relationships between the strength limits of ice and its temperature, salinity, and density. To solve a similar problem, various scientific groups conducted field studies and tests with the Dikson icebreaker (Russia) for cutting ice with a jet of temperature-activated water or laser radiation with a power of 30 to 200 kW, which is transmitted via an optical fiber cable. Compared with the considered methods, which have disadvantages in the following: – mobility of devices; – weight of devices; – uninterrupted supply of the emitter with a sufficiently large power for an indefinite time; – formation of boiling water, which is formed during laser cutting of ice, which, in turn, at negative outside air temperatures, leads to a rapid coalescence of the section, which becomes much stronger; – laser-cut pieces of ice within the channel will go under the vessel. In the presence of shallow depths, this may stop the movement of the vessel or create a risk of damage to the hull. Thanks to the research results, it is possible to create an experimental self-propelled automated installation for the destruction of ice in freezing waters and on approach channels to the port, which allows: – soften the ice at the first stage of work; – at the second – cut it; – at the third – turn it into water.


Introduction
The ice situation in the eastern part of the Black and Azov Seas (Ukraine) lasts from three to five months a year. The experience of independent navigation of ships and ice pilotage of ship caravans at that time showed a very high percentage of damage to ship hulls as a result of ice movements and ice compression [1]. Due to such circumstances, navigation safety is not guaranteed, and ice navigation becomes risky. The results of studies on the possible use of various technical means for piloting and facilitating the navigation of ships in ice conditions are presented in many published scientific papers, for example, in [2][3][4]. But experiments conducted by the authors of these works do not take into account shallow depths and ice movement. Therefore, it is relevant to conduct research aimed at ensuring independent navigation of vessels and as part of ship caravans in the Azov Sea and in the coastal eastern regions of the Black Sea. Thus, the object of research is the effect of infrared radiation of different wavelengths on ice. And the aim of the first stage of the work is studying the temperature distribution in the ice section when it is irradiated with infrared radiation with different wavelengths.

Methods of research
In the laboratory, mercury laboratory thermometers with a scale of 0.2 °C were installed in the interior of the frozen ice. When ice was irradiated with infrared radiation with a different wavelength coming from a manufactured adjustable infrared device, the temperature was recorded on each thermometer depending on the exposure time and the temperature of the source of the infrared emitter.

Research results and discussion
The readings of the above thermometers are entered in Tables 1-10.
As a result of the analysis of the obtained data, changes were found in the optical and mechanical properties of ice, worsening its strength characteristics, both on the surface and inside (Fig. 1). It was also found that the speed of ice melting when exposed to infrared radiation is insufficient for the passage of a vessel in ice with a given speed. Therefore, in addition to the effects of infrared radiation, softening the ice, it is necessary to investigate the installation of its mechanical grinding and melting. Taking into account the fact that the resistance of ice to a slice has the smallest parameter (Table 1), it is most advisable to study a mechanical device operating on a slice, determining the optimal speed of rotation and cutting of ice. Since this parameter is functionally related to the speed of the vessel in ice (2-3 knots). In the considered option, the method and a special manipulator device are studied in a laboratory, which will work in tandem with the vessel for its safe passage in the places of formation of hummock, solid and drifting ice with a thickness of 0.4-0.5 m. When the ice thickness is exceeded more than 10-15 see, a remotely controlled manipulator device is lowered onto the ice and moving along a given route carries out thermal destruction of the internal part of the ice by infrared radiation (λ = 4 μm). At the same time, it crushes it with a special rotating and cutting ice device with cutters, reducing ice loads on the ship's hull and ensuring a safe possible speed of the ship (2-3 knots) along the laid route. Rapid melting of crushed ice at low ambient temperatures and an increase in the time it is in the unfrozen state is ensured by an additional infrared emitter with λ = 3 μm, located behind a special rotating device. Also, this emitter prevents an increase in ice hardness upon repeated freezing of crushed ice.
Since the resistance of the ice to the slice is approximately 2 times less than the rupture and 4 times less than the crushing [5] (Table 1), it is most advisable to consider and investigate the device working on the slice and determine the optimal speed for cutting ice. This parameter is functionally related to the speed of the vessel, the relief of the true thickness of the ice, and the relief of the temperature field of the ice cover [6]. At the first stage of the experiment, studies were carried out on the interaction of the infrared radiation spectrum on ice. According to the Wien formula [7], a temperature range was determined and an adjustable installation of radiant energy was made. Such a setting has a black factor close to unity. This means that most of the thermal energy is converted into a stream of electromagnetic waves [8]. The flow of electromagnetic radiation from a distance of 200 m was directed onto the ice plane, the wavelength changed and with the help of mercury laboratory thermometers the temperature was recorded in four places evenly separated from each other by thermometers.
The results are shown in Tables 2-10, and the temperature distribution in the ice section upon irradiation with infrared rays is shown in Fig. 1.      Modern remote systems give only averaged readings using sequential comparisons of image signals using a variety of standards [9]. Given the fact that the skipper in order to decide on the use of this device needs to know the thickness of the ice, it becomes possible to conduct full-scale studies of the device to determine the thickness of the ice [10].

Conclusions
In the course of the study, it was determined that the transparency of ice clearly varies depending on the change in the wavelength of electromagnetic radiation, which penetrates deep into the ice and is effectively absorbed by it, increasing the temperature inside the ice. Clean air does not absorb infrared rays, and water absorbs all radiant energy in a very thin layer and its temperature is higher than the temperature of ice. A shorter wavelength with greater heating is opaque to ice and radiation energy is released on the ice surface. The peak of transparency in ice is in the region of 4-6 μm. In this range, the inside of the ice softens. The softened inner part of the ice will reduce the load on the electric drive, and the choppers of the grinder, eliminating freezing and speeding up the passage of the vessel along the laid path.
The research results will be useful when conducting full-scale tests during the ice navigation period to determine preliminary data on the ice parameters of the navigation area and to calculate the true thickness of the ice relief and the relief of the temperature field of the ice cover [11].