N. N. Smirnov

Lomonosov Moscow State University | MSU · Faculty of Mechanics and Mathematics

The preliminary results are presented for the last flight of the Spacecraft Fire Experiment (Saffire VI) which was conducted on an orbiting Cygnus spacecraft. These experiments directly address the risks associated with our understanding of spacecraft fire behavior at practical length scales and geometries. The lack of this experimental data has fo...

This paper presents the results of the two-dimensional modeling of the hydrodynamic instability of a detonation wave, which results in the formation of an oscillating cellular structure on the wave front. This cellular structure of the wave, unstable due to its origin, demonstrates the constant statistically averaged characteristics of the cell siz...

A four-lane model is put forward to explore the effects on vehicular fuel consumption of a freeway work zone which has a length of 100 m and occupies lanes III and IV. The model equations are solved numerically in the simulation of vehicular flows by a method called WENO5–RK3. A vehicular fuel consumption model is presented, with an additional fuel...

This paper presents the results of numerical simulation of a model combustion chamber of a pulse detonation engine using the authors’ developed software package. The main goal of the present study is to numerically investigate the effects of cyclic operation of pulse detonating chambers, as the former studies have been limited to simulating one cyc...

The paper discusses the features of mathematical modeling of the process of oil displacement from a porous reservoir using thermochemical methods of enhanced oil recovery. An advantage of these methods is the following: as a result of an exothermic chemical reaction between the fluids, the oil temperature rises and the viscosity decreases, as a res...

Among the studies of the effect of rock’s heterogeneity on hydraulic fracture propagation, very little information on the effects of the heterogeneity of rock’s fracture toughness is available. The objective of the present paper is to develop a planar-3D model for studying the effect of the heterogeneity of rock’s fracture toughness on hydraulic fr...

This paper develops a three lane continuum model to analyze the effects of a work zone on vehicular flow on an annular freeway with a tunnel. The model expresses the mandatory lane changing rate just upstream of the work zone in an explicit algebraic form with the relevant random parameter generated from golden section analysis, and describes the d...

Space debris creates a serious problem for Space flights safety in Low Earth Orbits. In this paper, the results of high velocity Space debris fragment interaction with thin metallic shields are presented. The formulas for determining critical thickness of the target preventing from penetration being functions of impactor mass, speed and material pr...

To explore freeway tunnel effects on ring road traffic flow, a two-lane traffic model is put forward. The model adopts lane-changing time to describe the net lane-changing rate, assuming that the time is approximately equal to the relaxation time of traffic flow, but infinite when the absolute value of difference of traffic density between the two...

To ascertain tunnel effects upon road efficiency and travel time of ring road traffic, a mathematical model accounting of three lanes is investigated. The model uses traffic pressure and sound speed in algebraic form, and a single traffic speed to describe the vehicular motions on the three lane instantaneously to simplify mathematical modeling of...

The effectiveness of the hydraulic fracturing procedure is crucially dependent on the stage of fracture planning and design. Forecasting fracture behavior in rock formations characterized by non-uniform toughness is a serious challenge. In the present paper, a planar-3D model considering the rock’s non-uniform fracture toughness has been developed...

The paper investigates the influence of the presence and location of hydraulic fractures on the dynamics and quality of oil displacement. Particular attention is paid to ascertaining whether the presence of a hydraulic fracture increases the oil recovery coefficient or only intensifies oil production. The paper considers numerical modeling of two-d...

The detonation combustion mode is very attractive for being used in new propulsion systems. The onset of detonation is a key issue for the process. In this work, a three-dimensional numerical simulation of the processes of reflection and focusing of a shock wave in a wedge was done. The following possible scenarios for the development of processes...

The paper investigates peculiarities of infection evolution and spreading models in non-uniform biological systems of individuals (humans, animals, plants) using the approach of mathematical modeling. The effects of different characteristic features are revealed. A robust tool for prediction of infection evolution (growth and spreading) under diffe...

The problem of collision between spherical impactor and thin-walled containment involves geometrical multi-scale – shell thickness and impactor radius, specifically, 2 mm and 6 mm, are of two orders smaller than shell radius equal to 150 mm. Good spatial resolution for impactor and shell is required as their interfaces deformation is an object of i...

This paper presents a three lane model to explore tunnel speed limit effects on traffic flow numerically. The model assumes traffic flow on each lane has its own density and speed, highlights the role of local homogeneity of traffic flow between adjacent lanes to express the net lane-changing rate more simply in comparison with the existing lane-ch...

Annotation In this paper we analyze the wave's effects in the tether of a space tethered system. The space tethered system is considered as a “big” massive satellite or a spacecraft moving along a circular orbit and a smaller satellite (endmass) connected with the first one by flexible and stretchable long tether. A load can be transported along th...

The paper considers the process of imbibition in a porous medium under the action of capillary forces in microgravity. A description of experiments on the repeated imbibition of an artificial porous medium during parabolic flights is given. In some experiments, the porous medium is homogeneous; in others, the experimental cell contains regions with...

The spread and growth of flames over large solid fuel samples and their effect on the pressurized spacecraft were studied inside Cygnus spacecraft while in orbit after departing the International Space Station. These experiments were developed by NASA's Advanced Exploration Systems Division in the Human Exploration and Operations Mission Directorat...

All celestial bodies have defects in the form of cracks. Some of the bodies are large. Colliding with such objects can be dangerous. Therefore, the problem of grinding such bodies remains very urgent. In order to avoid large financial costs, you need to know where to strike in order to achieve the greatest effect. This paper studies the behavior of...

Speed limit of freeway tunnel restricts car driving behaviors. To explore the tunnel effect of travel time, a double lane traffic model is put forward, and a compensative function of mean travel time is simply introduced in this paper. The model describes the net lane-changing rate using the ratio of characteristic lane changing time to traffic rel...

To explore tunnel effects on ring road traffic flow, a macroscopic urgent-gentle class traffic model is put forward. The model identifies vehicles with urgent and gentle classes, chooses the tunnel speed limit as free flow speed to express the fundamental diagram in the tunnel, and adopts algebraic expressions to describe traffic pressure and sound...

To estimate travel time through a composite ring road, a viscoelastic traffic flow model is developed by assuming traffic sound speed on empty road is just equal to free flow speed. Based on the viscoelastic model, numerical tests of traffic flows were conducted to provide node traffic speed for estimating travel time. The composite ring road with...

One of the mechanisms of destruction of a solid is the formation and growth of “micro” and “macro” cracks. This task is especially acute for space objects. A microcrack in the body of the spacecraft practically does not affect its mechanical strength, but it can lead to depressurization of the body, which can lead to the loss of life support for th...

Expanding the role of Space Physical Science and Technology in the modern world comes through the application of digital technologies and supercomputing. The present paper is aimed at getting the readers acquainted with results of resent scientific discussions on the topic having taken place at specialized scientific forums supported by the Interna...

The paper presents the results of theoretical, numerical and experimental investigations of combustion and detonation initiation in heterogeneous poly-dispersed mixtures. The problems of fuel droplets atomization, evaporation and combustion and the non-equilibrium effects in droplets atomization and phase transitions were taken into account. The ef...

Combustion simulations are the key aspect for full-scale 3D simulations of modern and perspective engines for aerospace propulsion. The present work studies an opportunity to solve chemical kinetics problems using artificial neural networks. Using classical numerical methods, sets of training data were produced. Choosing among different architectur...

In this work the problem of stability of the space tethered system for load transportation along the tether is considered. The whole system is designed to “clean” orbits of space debris. The system consists of a «big » satellite moving along a circular or slightly elliptical orbit (orbital station or some satellite for orbital missions where fragme...

The numerical asymptotic solution to the initial condition problem (early-time solution) of the pre-existing plane-strain hydraulic fracture with a fluid lag is obtained under different levels of in-situ stress. This solution can provide a more accurate initial condition for simulation of hydraulic modelling. The perturbation method is applied to c...

Novel, high-fidelity results related to soot from microgravity flames were obtained by an international topical team on fire safety in space. More specifically, embedded optical techniques for evaluation of the soot-related radiative feedback to the base material from a spreading non-premixed flame in microgravity were developed. The configuration...

For analyzing the risks of Space missions and reliability of joint functioning of on board equipment the virtual simulations become one the most effective tools of ground based studies. Analyzing multiplicity of scenarios of malfunctions and taking decisions within the real time artificial intelligence systems should be used, which had been previou...

The paper presents results of analysis of existing mathematical models for orbital debris fragments breakup in high velocity collisions. The breakup models are modified and updated taking into account the latest breakup criteria, experimental data and basic conservation laws. The model examples are analyzed, the criterion is developed for distingui...

The paper continues the numerical investigation for the problem of hypervelocity impact of a spherical projectile against thin-walled metallic containment that is a key process in the space vehicles shielding by composite honeycombs. The features of initial outward penetration process are studied for wide variation of projectile and containment mat...

Strength of Space vehicles is a crucial issue for Space flight safety. The presence of latent defects in the material has a significant effect on the strength at different loads: the speed and direction of crack growth. In this paper, we study a three-dimensional elastic medium weakened by a system of plane cracks and one crack with a bend. As a nu...

This book contains abstracts of presentations of the 9th conference in the series "Space challenges of the XXI century" dedicated to the 100th anniversary of the outstanding scientific event: publication of K. E. Tsiolkovsky's book "Research of the world spaces by jet devices". Purpose of the conference SPACE’2019 was to promote international coop...

In this work dynamical processes in the tether of а space tethered system are considered. The whole system is designed to “clean” orbits of space debris. The system consists of a «big» satellite moving along a circular or slightly elliptical orbit (orbital station or some satellite for orbital missions where fragments of space debris can be capture...

The capillary driven seepage in porous media under microgravity conditions is investigated. Experiments on the flow of a liquid in an inhomogeneous artificial porous medium are presented. A non-stationary mathematical model of the flow of a multiphase fluid in a sample of a porous medium is described. The experimental data are compared with the res...

A 3D numerical model of a combustion chamber with continuous rotating detonation wave was performed. The ignition, onset and stabilization of a rotating detonation wave in combustion chambers of different shapes was investigated. The effect of additional oxygen injection on the onset of rotating detonation wave was studied. Formation of a stable de...

Travel time through a ring road with a total length of 80 km has been predicted by a viscoelastic traffic model (VEM), which is developed in analogous to the non-Newtonian fluid flow. The VEM expresses a traffic pressure for the unfree flow case by space headway, ensuring that the pressure can be determined by the assumption that the relevant secon...

Effectiveness of a honeycomb shield assembled of gas-filled containments is discussed. A numerical tool is developed aimed at investigating hypervelocity impact of a spherical projectile on thin-walled metallic containment filled in with gas or fluid. Variation of gas density inside the containment essentially affects perforation scenario and succe...

We represent results of numerical simulation of molecular clouds dynamical collision. The problem was considered in 3D on extremely high resolution computational grids. The choice of so highly detailed grids is necessary due to fulfillment of numerical Jeans instability. The numerical code was parallelized using OpenMP and CUDA. The code uses Autom...

For the first time, a large-scale flame spread experiment was conducted inside an orbiting spacecraft to study the effects of microgravity and scale and to address the uncertainty regarding how flames spread when there is no gravity and if the sample size and the experimental duration are, respectively, large enough and long enough to allow for unr...

The goal of the present paper is to investigate the capillary driven filtration in porous media under microgravity conditions. New mathematical model that allows taking into account the blurring of the front due to the instability of the displacement that is developing at the front is proposed. The constants in the mathematical model were selected...

To estimate travel time through a ring road, an urgent-gentle class traffic flow model (UGM) with viscoelastic and ramp effects is developed. Vehicles in traffic flow are divided into urgent and gentle categories, and the urgent class has the demand of arriving at destination in time, while the gentle class hasn’t. It is assumed that the urgent and...

Hydrogen fuel, as for now, is the most energy efficient and clean fuel for aviation engines. At present time RAM engines based on chemical burning of fuels and accelerating exhaust gases practically reached the top of their efficiency in terms of specific impulse. New schemes are under development. As it is known, complex geometry of combustion cha...

Meta-stable systems are those staying in the local equilibrium state: being slightly deviated from it they return to the equilibrium, but in case deviation surpasses a critical value those systems fall down to another equilibrium state. Chemically reacting gaseous mixture provides a typical example of a meta-stable system. The paper is aimed at num...

In this work, the issue of stable transportation of load on tether of the deployed system is considered aimed at cleaning up space environment by removing debris fragments. The analytical conditions on systems parameters for stable transportation are obtained. At these parameters the system can function without additional control and human influenc...

Paper presents the results of numerical studies of hybrid rocket engines operating cycle including unsteady-state transition stage. A mathematical model is developed accounting for the peculiarities of diffusion combustion of fuel in the flow of oxidant, which is composed of oxygen-nitrogen mixture. Three dimensional unsteady-state simulations of c...

The paper presents the problem of condensed material surface burning in a flow of oxidant within the framework of the assumptions of the laminar boundary-layer theory. It is used assumption of fuel gasification and gas phase chemical reacting in a diffusion flame. The regression rate of the material surface in the turbulent and laminar flow regimes...

The goal of this work is to study the applicability of modern GPUs for the computation of combustion and detonation problems for a nonstationary regime. The capacity of the graphics card and universal processors connected in parallel for solving problems of detonation initiation is compared.

The paper is aimed at modeling results of hypervelocity impact of space debris fragments on shielding elements of space structures. For this purpose we developed numerical model based on a smoothed particle hydrodynamics method. Verification and validation of the model was made in simulation of a process of a hypervelocity impact of a spherical pro...

The preliminary results for two flights of the Spacecraft Fire Experiment (Saffire), conducted on an orbiting spacecraft, are presented. These experiments directly address the risks associated with our understanding of spacecraft fire behavior at practical length scales and geometries. The lack of this experimental data has forced spacecraft design...

As part of the Saffire project, solid materials were burned aboard orbiting spacecraft in two sets of experiments. The materials, mounted within a large air flow duct, were substantially larger than fuel samples in all previous microgravity tests. Large-than-typical samples could be accommodated because the tests were remotely conducted in unmanned...

It was experimentally shown that the reaction of the combustion of hydrogen–air mixtures in a detonation wave virtually completely (with an accuracy of 1%) occurs by a branched-chain mechanism; it is this mechanism that determines the characteristics of the detonation wave.

We discuss the problem of simultaneous dynamical stabilization and suppression of transverse and longitudinal vibrations of the space tethered system deployed along a certain trajectory. The dynamics of the system is described by a system of nonlinear partial differential equations for the longitudinal and transverse waves and we consider a non-cla...

The aim of the present study is to calculate the process of detonation combustion of gas mixtures in engines. Development and verification of 3D transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen was performed. Development of a computational model based on the mathematical one for parallel computing on supe...

The aim of the present paper is to study detonation initiation due to focusing of a shock wave reflected inside a cone. Both numerical and experimental investigations were conducted. Comparison of results made it possible to validate the developed 3-d transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen – air...

Spacecraft on board electronic devices are subjected to the effects of Space environment, in particular, electromagnetic radiation. The weight limitations for spacecraft pose an important material and structures problem: developing effective protection for on board electronic devices from high frequency electromagnetic radiation. In the present pap...

This letter reports traffic flow sensitivity to visco-elasticity, with the traffic flow modelling briefly described at first and then used to do traffic flow simulations whose results can reflect the properties of spatial-temporal evolution of ring traffic flow. It reveals that visco-elasticity plays crucial role on formation of traffic flow patter...

This paper presents viscoelastic modelling of traffic flows briefly first and then shows numerical simulation results of ring traffic flow sensitivity to model parameters, such as viscoelasticity, average vehicle length, braking distance, and characteristic length used to define relaxation time. It was found that traffic flow pattern formation is d...

Study of the combustion and explosion of hydrogen¯carbon oxide¯air mixtures shows that the sharpness of a chain thermal explosion depends on the frequency of branching in a given branch of a reaction chain. It is established that varying the CO: H2 concentration allows us to observe and eliminate the degeneration of an explosion while maintaining t...

The report is devoted to numerical simulation of interaction between the post-shock wave frontal of supernova blast remnants and the gas of two molecular clouds (MC). The dynamical formation of MC structures associated with Kelvin-Helmholtz and Richtmayer-Meshkov instabilities occurring in the cloud and interstellar medium interaction zone is simul...

The aim of the present study is to investigate problems of numerical simulations precision and stochastic errors accumulation in solving problems of detonation or deflagration combustion of gas mixtures in rocket engines. Computational models for parallel computing on supercomputers incorporating CPU and GPU units were tested and verified. Investig...

The aim of the present study is to calculate the process of detonation combustion of hydrogen-air gas mixtures in engines. Development and verification of 3-d transient mathematical model of chemically reacting gas mixture flows incorporating hydrogen was performed. Development of a computational model based on the mathematical one for parallel com...