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The effect of a gas curtain, formed by the destruction products of thermal protection elements in the combustion chambers of solid-propellant gas generators, on the material degradation of critical-section liners is investigated. Experimental data from two series of fire tests conducted on test benches are analyzed: one series performed by the authors and another reported in the literature. Both test series yield relatively low linear material loss rates, measuring 2.5 and 6 times lower, respectively, than those calculated using methods for large-scale solid-propellant rocket motors. A mathematical model is proposed based on the coupled solution to integral momentum and energy equations for the boundary layer and on the determination of the thermal state and failure of materials. This model allows for the introduction of additional admixtures of a cold gas, which is chemically inert with respect to carbon, into the fuel combustion product flow. The applicability of the model is validated by comparing simulation results with experimental data, with discrepancies not exceeding 5%.

The kinetic physical-mathematical theory of metal creep, which accounts for thermally activated dislocation glide, is applied to describe the creep process under uniaxial tension for the EI696 steel and the EI826 nickel alloy under non-stationary thermomechanical loading conditions. The new results obtained in this work demonstrate the potential of this theory for applications in aircraft design.

The fabrication of Al-metallic glass (Fe₆₆Cr₁₀Nb₅B₁₉) composites with low residual porosity and varying component concentrations is presented. During sintering, no interfacial interactions between the composite components are observed. The hardness and thermal conductivity of the Al-metallic glass composites are experimentally determined. The experimental data are compared with values calculated using the rule of mixtures. The measured thermal conductivity of composites containing 20 and 80 vol.% metallic glass closely matches values predicted by models for parallel and series phase connectivity, respectively. The hardness values for these composites are consistent with those calculated using the Reuss and Voigt models.

An experimental setup for free circular rotation of blunt bodies about their longitudinal axis is described. A procedure for determining the roll moment in wind tunnel tests is presented. A method for determining the equivalent aerodynamic roll damping coefficient is developed, based on the fact that the viscous friction moment component in rolling bearings is independent of the axial load. For a segmental-conical body, the experimental value of the coefficient is shown to be close to the value calculated by numerical integration of the continuum equations in a quasi-stationary approximation. The proposed method can be used to determine the roll damping moment of reentry vehicles, which is necessary for solving flight dynamics problems.

Results of a combined computational and experimental study of the vortex structure in the reattachment region of a separated flow at a freestream Mach number M_∞ = 6 are presented. Three compression corner configurations are examined: a compression corner formed by two flat surfaces, the same compression corner with sidewalls, and an axisymmetric model. The compression angle is identical in all cases, equal to 30°. The model geometry is found to significantly affect the structure and parameters of the vortex flow in the reattachment region. This specifically pertains to the presence or absence of longitudinal Görtler-type wall vortices, their geometric dimensions, and the magnitude of the force and thermal parameters in this region.

The distributed receptivity of a swept-wing laminar boundary layer to unsteady freestream vortices with a longitudinally oriented vorticity vector in the presence of uniform spanwise surface undulations is experimentally investigated. Experiments are performed on a 25° swept-wing model under fully controlled disturbance conditions. Unsteady longitudinal freestream vortices are found to induce highly efficient distributed (in the streamwise direction) excitation of unsteady cross-flow instability modes at combination spanwise wavenumbers. This excitation results from vortex scattering by surface inhomogeneities. Part 1 of this study (published in the previous issue of the journal) describes the experimental approach and its theoretical justification; the experimental setup; the mean flow structure; the method of disturbance generation; the characteristics of freestream and surface disturbances; experimental evidence for the high efficiency of the investigated receptivity mechanism; the important role of longitudinal wavenumber resonance in exciting the most amplified cross-flow instability modes. Part 2 of this study (the present paper) presents the experimental determination of the amplitudes and phases of the distributed vortex-roughness receptivity coefficients as functions of disturbance frequency and spanwise wavenumber. Receptivity coefficients responsible for cross-flow wave excitation on a smooth surface are also obtained, and the relative efficiencies of the distributed vortex receptivity and vortex-roughness receptivity mechanisms are compared. The results are further compared with those previously reported for distributed vortex receptivity on a smooth surface.

The feasibility of controlling turbulent incompressible flow over an asymmetric Clark Z airfoil is investigated using two passive techniques. Firstly, air bypass through perforated surface regions from a high-pressure to a low-pressure area. Secondly, an external pressure flow introduced through the leading edge of a wing and subsequently diverted to its lower surface. The study is conducted over a chord within a Reynolds number range Re_c = (0.40-1.28) × 10⁶ and angles of attack from -6° to 6°. The examined control method exhibits an ambiguous effect, which depends significantly on the length and chordwise position of the mass-transfer region, the angle of attack, and the Reynolds number. Under certain conditions, however, a reduction in airfoil drag of 4-5% and an increase in lift are achieved, leading to an improvement in aerodynamic efficiency.

Results of the first combined computational and theoretical study of the effect of flow-aligned rectangular depressions (slots) on the surface of a flat plate on boundary-layer stability at a freestream Mach number M_∞ = 2 are presented. Slots of various depths (Reynolds number 0 ≤ Re_h ≤ 5400) and small width relative to the instability wavelength are considered. The mean flow is obtained using the FlowVision computational fluid dynamics package. Linear stability theory calculations reveal that increasing slot depth shifts the frequency range of boundary-layer instability toward higher frequencies. The spatial growth rates of the disturbances become lower than those for a boundary layer over a smooth surface, indicating flow stabilization.

The paper considers an algorithm for numerical solving of a one-dimensional inverse magnetotelluric sounding problem. The algorithm is based on a special type of algebraic equation which is called a pseudo-quadratic equation. The inverse problem is considered in three variants: 1) for media with fixed geometry; 2) for media with fixed geoelectrical properties; 3) general case. Additionally, an algorithm is proposed for input data processing which provides the existence of a solution to the inverse problem. Numerical experiments realized on test media with different sets of parameters are carried out to study and illustrate the efficiency of the proposed algorithms.

The paper is devoted to modeling the propagation of seismic waves in a chemically inert elastically deformable rock. Only changes in stress and pore pressure are considered, and the chemistry of the saturating pore fluid does not directly affect the deformation of the rock. Chemical effects are taken into account by changing pore pressure and rock deformation in the transport equations. In the numerical solution of the problem under consideration, an algorithm is used to combine a Laguerre integral transform method and a finite difference method. The paper presents results of modeling of the transport of a dissolved substance through a semi-permeable clay shale.