Vestnik Moskovskogo gosudarstvennogo tehničeskogo universiteta imeni N.È. Baumana 

About: Vestnik Moskovskogo gosudarstvennogo tehničeskogo universiteta imeni N.È. Baumana is an academic journal published by Bauman Moscow State Technical University. The journal publishes majorly in the area(s): Chemistry & Computer science. It has an ISSN identifier of 1812-3368. Over the lifetime, 75 publications have been published receiving 31 citations. The journal is also known as: Herald of Bauman Moscow State Technical University. Series Natural sciences & Vestnik Moskovskogo gosudarstvennogo tehničeskogo universiteta imeni N.È. Baumana. Seriâ Estestvennye nauki.

Mathematical Modeling of Heat and Mass Transfer During Aerodynamic Heating of the Nose Parts of Hypersonic Aircraft

Abstract: The study focuses on heat and mass transfer on the side surfaces of blunt nose cones of hypersonic aircraft under aerodynamic heating conditions and formulates the problem of viscous flow and heat and mass transfer in dynamic, thermal, and diffusion boundary layers. After minor simplifications, we found approximate analytical solutions related to the gas-dynamic, thermal, and diffusion characteristics of the dissociating flow and obtained closed analytical expressions for the distribution of enthalpy and concentrations of the gas mixture components over the thickness of the boundary layers. Furthermore, by the derivatives of the enthalpies and concentrations distributions with respect to the vertical variable on the wall, we determined convective and diffusion heat fluxes to the aircraft surface. Using the balance between the supplied convective-diffusion heat fluxes and the fluxes removed due to radiation and heat elimination into the body, we obtained a nonlinear equation for the wall temperature, which is solved numerically. Numerical results are obtained and analyzed on convective-diffusion heat fluxes and wall temperatures of hypersonic aircraft, depending on the Mach number and flight altitude in a wide range of values, which make it possible to determine the boundaries of speeds and altitudes at which the mass of the heat-shielding coating is not removed. Finally, we investigated the influence of the catalytic properties of the aircraft surface on heat transfer in the same ranges of the Mach number and flight altitude

Mathematical Simulation of Thermal Shock Wave Dynamics in Nonlinear Local Non-Equilibrium Media

Abstract: We performed a mathematical simulation of heat transfer in a local non-equilibrium medium whose transfer characteristics are functions of the temperature distribution. A homogeneous polynomial of arbitrary degree represents nonlinearities in thermal conductivity and thermal diffusivity. The mathematical model consists of a hyperbolic nonlinear heat transfer wave equation, initial conditions and nonlinear boundary conditions of the second and first kind. To solve this problem, we used a conservative homogeneous finite-difference scheme along the upper time grid line (implicitly). We then used the tridiagonal matrix algorithm of the second order in the spatial variable and of the first order in time to solve the resulting system of linearised algebraic equations. A periodic series of rectangular temperature or heat flux pulses form the boundary conditions of the first and second kind. Computation results reveal ultimate propagation rates of temperature and heat fronts featuring pronounced first-kind discontinuities with attenuating magnitudes. As the process unfolds, the initial pulses heat the region between the boundary and the heat wave front, while the subsequent pulses traverse this region at a higher velocity due to thermal diffusivity being a function of temperature, their fronts "catching up" with the previous fronts, increasing the discontinuity magnitude at the initial pulse front, that is, forming a thermal shock wave front similar to that of a shock wave in gas dynamics. We obtained such thermal shock waves for boundary conditions of both the first and the second kind. We also analysed kinematic and dynamic characteristics of thermal waves

Notes on Strongly Semi-Closed Graph

Abstract: In these papers, we study on mapping with strongly semi-closed graph. We first introduce the notion "strongly semi-closed graph" in analogue to the closed graph. Also, we study some of their basic properties. This study proved that: If Y is extremally s-disconnected semi-T2-space and f : X → Y is a set-s-connected surjection, then G(f) is semi-closed. If Y is Hausdorff space and f is almost semi continuous, then G(f) is strongly semi-closed. If Y is semi-T2-space and f is irresolute, then G(f) is strongly semi-closed. Semi-closed mapping and semi-closed graph are two separate concepts. If G(f) is a semi-closed and f is surjection(onto), then Y is semi-T1-space. If the injective S**-open map X is semi**-connected and G(f) is semi-closed then X is semi-T2-space provided it is T1-space and locally semi-connected. S**-closed mapping and semi-closed graph are two separate concepts. If Y is semi-regular space, then the following are equivalent G(f) is semi-closed and G(f) is strongly semi-closed

T-Schemes for Mathematical Modelling of Vorticity Generation on Smooths Airfoils in Vortex Particle Methods

Abstract: New numerical schemes are proposed for solving the boundary integral equation that arises in CFD vortex particle methods of when simulating a plane flow around smooth airfoils. They are based on considering the 2-nd kind integral equation with respect to vortex sheet intensity with a bounded or absolutely integrable kernel instead of traditionally solved singular integral equations of the 1-st kind with Hilbert-type singularity. To solve it, the Galerkin approach is used. It is shown that when approximating the airfoil boundary with a polygon, it is possible to develop schemes of the 1-st and 2-nd order of accuracy, considering a piecewise-constant or piecewise-linear (discontinuous or continuous) distribution of the solution along the panels. The necessary formulae are presented for calculating the components of the matrix and the right-hand side of the system of linear algebraic equations, that is a discrete analogue of the integral equation. They are suitable for modelling of the vorticity generation when simulating the flow around either single airfoil or system of airfoils, including moving and/or deformable ones. The developed schemes can be used in the framework of the viscous vortex domains method as well as other modifications of vortex particle methods, since they only concern the convective velocities of the flow near the airfoil and are not related to methods for modeling viscous diffusion of vorticity

Describing Non-Axisymmetric Elastic Fields Generated by Volume Forces in Anisotropic Solids of Revolution

Abstract: The paper presents a technique for plotting elastic fields in transversely isotropic bodies bounded by coaxial surfaces of revolution, subjected to non-axisymmetric volume forces. Our theory uses the ideas of the boundary state method, which is based on state spaces describing a medium. Fundamental polynomials form the basis of the internal state space. A polynomial is placed in any displacement vector position in a planar auxiliary state, then transition formulas can be used to determine the spatial state. A set of such states forms a finite-dimensional basis that is used after orthogonalisation to expand the desired elastic field characteristics into Fourier series with identical coefficients. These series coefficients are dot products of given and base volume force vectors. The search for an elastic state is reduced to solving quadratures. We provide guidelines for constructing an internal state basis depending on the type of volume forces given by various cyclic functions (sine and cosine). We analysed a solution to a specific theory of elasticity problem concerning a transversely isotropic circular cylinder subjected to non-axisymmetric volume forces. We analysed the series convergence and graphically evaluated the solution accuracy