A description of a small icing wind tunnel designed for studying the icing processes at the Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences is presented. The use of such a wind tunnel offers a possibility not only of studying the physical features of the icing process, but also of testing methods of anti-icing control, validating numerical methods used for calculating the icing processes, etc.

An Erratum to this paper has been published: https://doi.org/10.1134/S0031030121340013

The results of an experimental study of a pair of interacting vortices at Mach number of 3 are presented. Laser sheet visualization were performed at various longitudinal coordinate values. The mutual influence of the fact of interaction on the vortex cores size is shown in comparison with the case of an isolated vortex. The results obtained compared to the results of numerical simulation.

A conceptual design of the "Structural Diagnostics" diffraction beamline 1-2 for "SKIF" synchrotron radiation facility (Koltsovo, Novosibirsk area, Russia) is presented. The beamline will be dedicated to various diffraction techniques (powder X-ray diffraction, single-crystal X-ray diffraction and SAXS). All the techniques will be implemented in in situ and operando modes to enable real-time monitoring of chemical, physical, or engineering processes. The paper describes scientific scope of the beamline, basic X-ray optical scheme and equipment that will be available at the end-stations. Results of simulations and ray tracing aimed at the optimization of the instrumental resolution and flux are also given.

The Khasurty locality (Lower Cretaceous of Transbaikalia, Russia) is one of the largest fossil insect sites in the region. Over the entire period of study, more than 6000 insect imprints have been collected here, representing 16 orders and 130 families. Dipterans, aphids and hymenopterans are the most common forms here, the most diverse taxa are Diptera, Hymenoptera, Coleoptera and Trichoptera. In addition to insects, remains of crustaceans, mosses, liverworts and vascular plants were found in Khasurty, as well as occasional finds of arachnids, bird feathers and fish scales. Two new families, 17 new genera and 21 new species of Trichoptera, two new species of Orthoptera, one new genus and species of Phasmatoptera, one new species of Reculida, three new genera and species of Hemiptera, a new genus and species of Thysanoptera, a new genus and species of Hymenoptera, a new subfamily, two new genera and six new species of Lepidoptera, three new genera and four new species of Neuroptera, as well as a new genus and species of liverworts are described. In terms of the composition of the fauna and flora, the Khasurty locality is very peculiar, it includes both Jurassic and Cretaceous taxa, but in general it can be attributed to the Jehol biota.

The paper presents the processing of the results of numerical simulation of the vortex flow in the wing wake, the purpose of which is to search for the vortex core center. It is based on the results of numerical simulation of the vortex flow in the wake behind of the rectangular wing, performed at the Keldysh Institute of Applied Mathematics RAS. The center of the vortex core was determined in several ways: by the minima of the total and static pressure, the axial Mach number, mass flow rate, the maximum of axial vorticity, and as the center of mass of the axial vorticity distribution. A comparison of the results of determining the position of the vortex core center showed good quantitative agreement. As a result dependencies of vortex core center coordinates on longitudinal coordinate were obtained.

In this paper an investigation of an acoustic type waves influence on a wingtip vortex wake parameters was performed in a supersonic flow. The supersonic flow around a straight wing with sharp leading and trailing edges was considered at an attack angle of 10 degrees at Mach number of incoming flow M = 2.Perturbations were introduced into a steady state stream in the form of monochromatic plane waves with small amplitude. Numerical simulations were carried out at the Keldysh Institute of Applied Mathematics RAS using the parallel algorithm for turbulent flow simulation. For the numerical studies an approach based on the URANS method with using the SA turbulence model was applied. Numerical simulations were carried out on the supercomputing system K-60.Numerical data were obtained in the area exceeding 30 wing chords downstreamfrom a wing axis. A numerical data on the pulsation of gasdynamic parameters in the vortex wake influenced by disturbance are obtained, in particular, frequencies and disturbance ranges on the wingtip vortex axis are investigated depending on a distance from the wing - vortex generator.

Actual problems arising during the study of supersonic vortex flows are shown using the example of a vortex wake behind of a rectangular half-wing. The main idea of the article is that supersonic vortex flows are complex objects that can only be investigated using a set of experimental methods, each of which does not provide complete information apart from the rest, however, the joint interpretation of the results along with numerical simulation data allows conclusions to be drawn that would not be possible using each of the methods separately.

Wind tunnel experiments often includes optical diagnostic of the flow. It is mostly used only for obtaining qualitative information on flow structure. However, interference methods also can provide quantitative information on density variations along the optical path length. A change in density of studied flow inhomogeneities leads to shift of fringes in the interference pattern. The results of the application of the optical method for determining the integral density field during the study of a vortex wing wake are presented. The optical diagnostics of the flow was performed by means of adaptive visualizing transparencies based on the saturation of absorption effect. To translate infinite interference fringes into finite ones, an optical wedge was used. The principal possibility of using the method for obtaining quantitative data on flow parameters in the study of the longitudinal end vortex is shown.

The results of experimental study of the flow in the wing wake at Mach number range M = 2 - 4 and angle of attack of 10 degrees are presented. Experiments were carried out in supersonic wind tunnel T325 of ITAM SB RAS. Rectangular half-wing with sharp edges was used to generate vortex wake. Constant temperature hot-wire anemometer was used to measure mass flow and its pulsations. The hot-wire data were compared with 5-hole pressure probe data.

Changes in insect biodiversity in terms of the number of families throughout the history of the class are described. The results are compared with those published recently by other researchers and possible reasons for observed differences are discussed. The main stages in the evolution of insect diversity are recognized. The per-family rates of the appearance and extinction of families, the mean longevity of families existing during certain periods of the geological time, and the rates of renewal of entomofauna are considered.