The article presents methodological and technological solutions for geodetic support of the LIA-20 linear induction accelerator design and assembly. Based on the facility geometry and the accelerator elements positioning tolerances, the arrangement scheme was developed for reference geodetic network signs. To assess the accuracy of the geodetic signs mutual location and the laser tracker positioning in the accelerator hall, the results of mathematical modeling were studied. To coordinate the facility design with the structure of the accelerator, a survey was carried out, so the spatial model of the building was obtained. Here we show the procedures of elements’ axes determination and corresponding local coordinate systems construction for elements of accelerator. The solutions for fixing the coordinate system of the entire accelerator complex are given. The processes of equipment installation and setting into the design position are reported. The data showing the dynamics of the reference geodetic network signs relative displacement over 6 measurement cycles (2018 - 2024 period) are presented.

The Budker Institute of Nuclear Physics is conducting research on the generation of multi-megawatt radiation fluxes in the frequency range of 0.1–1 THz. Currently, based on the prospects for practical use of such radiation fluxes, this work is focused on a local region of 0.3 THz, which corresponds to a wavelength of 1 mm. To study the radiation flux in this local frequency range in detail with high spectral resolution, we are developing a radiometric diagnostic system based on a heterodyne method for signal recording with high temporal resolution. One of the key components of this frequency-selective diagnostic system is a balanced mixer, which must generate a signal at a frequency equal to the difference between the frequency of the signal being studied and the reference frequency of the reference signal. This paper describes the characterization results of a balanced mixer supplied by MWave for use in the frequency range of 0.2–0.3 THz. Measurements were conducted around 0.3 THz with the working and reference signals supplied as radiation beams through quasi-optical paths. The working signal frequency varied from 288 to 294 GHz. The reference signal at a reference frequency of 290.85 GHz was provided by a Gunn diode. The measurements demonstrated the linearity of the difference signal frequency dependence on the frequency difference between the signals supplied to its two inputs. The frequency resolution of the local oscillator with this balanced mixer was found to be no worse than 0.1%.

Investigation on gas flow velocity pulsations characteristics in subsonic turbulent jet initial section exhausting into a submerged space was conducted. The geometric Mach number at the nozzle exit is M_a = 0.85. A comparison between data obtained using the contactless panoramic PIV method, flow probing with a total pressure tube, and numerical modeling was performed. The possibility of using the PIV method to estimate flow velocity pulsations parameters is shown and some sources of measurement error are identified.

This paper presents the results of a numerical study of flow in an axisymmetric vortex chamber with an annular obstruction on the end wall. The Reynolds number, based on the average flow velocity in the tangential slots of the swirl generator and the chamber radius, was Re = 3,4·10^⁴. Using direct grid resolution of the spatial scales of the viscous incompressible air flow, data were obtained on the distribution of static pressure on the chamber walls, as well as the velocity field in the internal volume.

Calculations were performed both for a chamber with a smooth lower end wall and for one with an annular obstruction. The diameter of the obstruction was varied relative to the diameter of the chamber’s outlet orifice, taking values of 1D, 2D, and 3,43D. The height of the obstruction remained constant at 0,3D in all cases considered.

The analysis of the obstruction’s influence was carried out by comparing the results with the distributions in the chamber with a smooth end wall. It was found that the placement of the obstruction leads to an increase in static pressure near the axis and an increase in the chamber’s resistance, while also affecting the shear stresses in the end-wall boundary layer and the flow patterns throughout the entire volume of the vortex chamber.

This article is devoted to an experimental study of the aerodynamic characteristics of an H-shaped arch bridge suspensions, a type of suspension widely used in construction but understudied from aerodynamic perspectives.

The relevance of this study stems from the need to predict the aeroelastic vibrations of flexible structures with non-standard cross-sections.

The study was conducted in the T-503 wind tunnel at NSTU using three types of models: a full-scale H-shaped suspension cross-section and, for comparison, square and rectangular cross-sections circumscribed around it. The aim of the study was to experimentally determine the influence of cross-section shape on the averaged aerodynamic force coefficients.

The results showed that the presence of protruding flanges in the H-shaped cross-section has a significant impact on the aerodynamic characteristics. It was found that for a cross-section with an aspect ratio of B/H = 0.91, the den Hartog criterion decreases by 53% compared to a smooth rectangular cross-section, indicating a significant reduction in galloping tendency.

The practical significance of this work lies in providing detailed aerodynamic coefficients for the design of bridge structures, which allows for more accurate assessment of wind loads and mitigation of the risk of aeroelastic vibrations. The scientific novelty is confirmed by the identification of a positive aerodynamic effect of protruding shelves, which justifies their use not only for technological reasons, but also to increase the wind resistance of structures.

Methods for measuring the characteristic sizes of detonation cells based on point-by-point processing of photographs of self-illumination of areas of impacts of transverse detonation front waves have been developed and tested. The techniques are used under conditions where continuous trajectories become difficult to distinguish due to the small distance between them and the merging of cell boundaries with the general background. Such points with increased brightness at the moments of oncoming collisions of transverse waves make it possible to complete the trajectories of transverse waves and determine the size of small detonation cells. The results of experimental studies of detonation wave propagation in stoichiometric combustible acetylene/oxygen and methane/oxygen systems are presented. Data on the area of existence of stable cellular structures in these mixtures, as well as the transverse dimensions of individual cells, have been obtained. The data on the size of cells obtained by the proposed method is compared with known traditionally used methods. The correspondence of these data was established using the example of stoichiometric combustible mixtures acetylene/oxygen and methane/oxygen.

In this paper, the properties of computational models based on nickel (Ni), aluminum (Al), and Ni₃Al intermetallic compounds are investigated when impurity hydrogen atoms are introduced and elastic deformation is applied. It is shown that an increase in the hydrogen concentration reduces the internal energy of the system, stabilizing it, while lattice compression and high temperatures destabilize the system. NI₃Al turned out to be the most sensitive to hydrogen embrittlement. The results can be used to optimize materials in hydrogen power engineering and aviation technology.