A method has been developed for constructing correction factors to compensate for distortions introduced by non-uniform frequency characteristics of the electronic path of a laser Doppler velocimeter into the spectral density of Doppler signals. The method relies on averaging a statistical ensemble of spectral densities of noise signals obtained during illumination of a photodetector with a reference white light source, constructing the inverse function to the resulting averaged spectral density with truncation in the low- and high-frequency bands, and applying digital low-pass filtering to it. In the first part, a model numerical experiment was carried out. The gas flow velocity at the Vitoshinsky nozzle exit was measured with a laser Doppler anemometer in high-velocity modes. It has been shown that in high-velocity modes (200 m/s), the application of correction factors to the spectral density of Doppler signals allows estimating the average flow velocity with an error of no more than 5

An important part of an experiment or ongoing process is observation. In many fields of science and production, there is a great need for visual monitoring of the occurring process or its result [Irodov n.d.]. However, the inspection may be difficult or even unattainable due to the closed space in which the process under study takes place. One such example is vortex chambers, which serve to mix various gases and substances under pressure or at high temperatures. These are large chambers of a round or conical shape where everything that takes place inside is hidden from the direct view of the observer due to the need to seal the chamber itself. The operation principle of such chambers is based on the multiple circulations of a substance at high velocity in the cavity of the housing, where various substances can be supplied under pressure [Aronson et al. 2015].

The adaptation of the method of laser Doppler anemometry to the study of multiphase flows in slit channels of characteristic size of 1 mm has been carried out in the paper.The method of obtaining flow velocity profiles in slit channels has been developed.

The article considers issues of improving the metrological characteristics of the phase triangulation method for measuring the three-dimensional geometry of objects. The stability of measurement results is shown to be affected by the nonstationarity of ambient lighting. A method is proposed for filtering data collected by a photodetector during measurements via the phase triangulation method under non-stationary lighting conditions. This method relies on the frequency analysis of collected data and their filtering according to the first harmonic amplitude in the frequency decomposition of the signal. The proposed method in the form of a filtering algorithm was experimentally tested in a measurement system implementing the phase triangulation method. The filtering results obtained via the developed method using the frequency analysis of collected data were compared with those obtained via the filtering method relying on the amplitude modulation analysis of signal intensity recorded by the photodetector. The comparative analysis of filtering results obtained using the two methods showed the higher effectiveness (by more than eight times) of the proposed filtering method. The study results can be useful in processing and analyzing experimental results, as well as contributing to the development of optical methods for measuring the three-dimensional geometry of objects.

Laser Doppler anemometry (LDA) is one of the main non-contact methods for measuring the velocity characteristics of flows and pressure pulsations. Determining the quantitative patterns of the flow of multiphase liquids in small-sized channels is known to be a difficult task. The authors demonstrate the eventual use of LDA to study cavitation flows in slits with a height of 1.2 mm. The cavitation flow is created by means of the NACA0012 hydrofoil. The experimental equipment is positioned using a micro-displacement device. The distortion of the luminous flux through the channel walls is taken into account. This paper presents an algorithm for searching the central region of the slit. A method for filtering noise effects is described. The results of measuring the average flow velocity near the cavitating hydrofoil in the slit are provided in the article.

1 Оптическая диагностика многолуночных планшетов с реагирующей смесью при производстве 1 Институт теплофизики им.С. С. Кутателадзе СО РАН, г.Новосибирск, Российская Федерация * e-mail:

44 В. В. Рахманов 1 *, В. Г. Меледин 1 , Г. В. Бакакин 1 , С. В. Двойнишников 1 Исследование влияния квадратурных демодуляторов лазерных доплеровских анемометров на погрешность определения скорости 1 Институт теплофизики им.С. С. Кутателадзе СО РАН, г.Новосибирск, Российская Федерация * е-mail:

A numerical algorithm for fast search of the initial phase shift on phase images with arbitrary stepwise shifts is proposed. The algorithm is based on finding the minimum deviation of the model function from the measurement results. The interval search method used directly in the proposed approach made it possible to significantly reduce the computational complexity of the algorithm. The paper presents the results of measuring a three-dimensional profile by phase triangulation methods using the proposed algorithm. The obtained results confirm the efficiency and high practical value of the proposed phase image decoding algorithm.

The research was devoted to the problem of measuring geometric parameters of ice by the method of phase triangulation in a limited volume with refraction of optical signals. This method served to develop an algorithm of measurement and calibration. It was expedient to take into account the reflective properties of ice and the conditions of external lighting, as well as to ensure a minimum error in measuring the geometric parameters of ice. For this purpose, software complexes to control the quality of the measuring system with current parameters and to calculate the geometric parameters of ice, as well as a software and hardware complex for measuring the geometric parameters of ice by the phase triangulation method in a limited volume with refraction of optical signals have been developed. The measuring system was configured for a measuring volume with characteristic dimensions 100×100×60 mm. A measurement error of 12 microns has been achieved. Experiments were carried out to measure the geometric parameters of ice formed on a cylindrical surface. The values of the local thickness of the ice and the statistical value of the thickness of 1.6 mm have been restored. The developed technologies may be used in experiments on an aerodynamic stand for the study of icing processes aimed at creating anti-icing methods in various fields of industry.

Измерение характеристик калибровочной платформы КЛАД-11 Институт теплофизики им.С. С. Кутателадзе СО РАН, г.Новосибирск, Российская Федерация

С. В. Двойнишников 1 *, В. Г. Меледин 1 , В. О. Зуев 1 , В. Г. Главный 1 Оценка погрешности метода многоракурсной фазовой триангуляции и структурированного освещения для измерения трехмерной геометрии протяженных объектов 1 Институт теплофизики им.С.С.Кутателадзе СО РАН, г.Новосибирск, Российская Федерация

объекта методом фазовой триангуляции: автоматизированная калибровка параллельными сдвигами плоской мишени 1 Новосибирский государственный университет, г.Новосибирск, Российская Федерация 2 Институт теплофизики им.С.С.Кутателадзе СО РАН, г.Новосибирск, Российская Федерация

С. В. Двойнишников 1 *, В. А. Павлов 1 , В. О. Зуев 1 , Д. А. Ланшаков 1 Метод фазовой триангуляции и структурированного освещения для измерения трехмерной геометрии в условиях динамических помех 1 Институт теплофизики им.С.С.Кутателадзе СО РАН, г.Новосибирск, Российская Федерация