RAS Institute of Theoretical and Applied Mechanics
RAS Institute of Theoretical and Applied Mechanics
Yankovskii A.P.,RAS Institute of Theoretical and Applied Mechanics
Journal of Mathematical Sciences (United States) | Year: 2017
In the von Kármán approximation, we formulate the initial boundary-value problem of the dynamics of flexible isotropic and composite elastic beams-walls within the framework of two versions of the Timoshenko theory. We perform a qualitative analysis of the resolving system of equations of motion. It is shown that, in the geometrically linear statement, the dynamics of elastic beams is described by a hyperbolic system. At the same time, in the case of deformation of flexible beams, the system of resolving motion equations may change its type degenerating from a hyperbolic system into a system of mixed (composite) type. We develop finite-difference and variation-difference versions of the explicit (in time) “cross” scheme for the numerical integration of the posed initial boundary-value problems. On the basis of these numerical methods, we perform the numerical analyses of the dynamic flexural deformation of flexible metallic and composite beams under explosive-type loads. The result of these calculations demonstrate that, in almost cases, one can indicate the levels of loading of flexible beams under which the “cross” scheme becomes unstable, although the condition of stability obtained in the linear approximation is satisfied with a considerable margin. Thus, it is shown that, in the case of dynamic analysis of flexible beams, one can speak only about the practical stability of the “cross” scheme but not about its conditional stability. © 2017 Springer Science+Business Media New York
Schweigert I.V.,RAS Institute of Theoretical and Applied Mechanics
Journal of Experimental and Theoretical Physics | Year: 2012
The plasma sheath near the surface of a hypersonic aircraft formed under associative ionization behind the shock front shields the transmission and reception of radio signals. Using two-dimensional kinetic particle-in-cell simulations, we consider the change in plasma-sheath parameters near a flat surface in a hypersonic flow under the action of electrical and magnetic fields. The combined action of a high-frequency 2-MHz capacitive discharge, a constant voltage, and a magnetic field on the plasma sheath allows the local electron density to be reduced manyfold. © Pleiades Publishing, Inc., 2012.
Gulyaev I.,RAS Institute of Theoretical and Applied Mechanics
Ceramics International | Year: 2014
With the example of zirconium dioxide, a process for the plasma production of hollow spherical powders with controllable shell thickness has been studied. The formation of hollow microspheres, or microballoons, is achieved through melting of an initial porous powder in the plasma jet of a DC plasma gun. Hollow microballoons 40 to 125 μm in size with shell thickness 2 μm and over were obtained. The experience in measuring the characteristics of hollow microspheres, namely their sizes, density, and wall thickness, is outlined. A procedure for preliminary and final classification of powders which enables the production of spheres with desired volumetric density and wall thickness is proposed. © 2014 Elsevier Ltd and Techna Group S.r.l.
Gulyaev I.P.,RAS Institute of Theoretical and Applied Mechanics
Journal of Physics: Conference Series | Year: 2013
Conducting plasma processes under high or low pressure is an efficient way to affect the heat, mass and momentum exchange in a two-phase flow and this technique is widely used in such well-developed technologies as low-pressure plasma spraying (LPPS) and high pressure plasma-chemical processes. In addition operating pressure is a key parameter in novel plasma process for modification of hollow powders properties. Plasma processing of porous ceramic powders is an effective method of producing hollow spheres (HOSP) with predefined properties. Regardless the method hollow powders were produced their geometric and structural properties can be adjusted by re-melting in plasma of certain pressure: low pressure processing will expand hollow spheres and high pressure-contract it. Regulating the outer diameter of hollow sphere allows adjusting its shell thickness, apparent density, gas pressure in the cavity etc. Preliminary experiments with zirconia hollow powders demonstrated good agreement with theoretical estimations of HOSP properties. The same technique can be used for adjusting properties of ceramic hollow powders produced by different methods, including cost effective fly-ash particles (cenospheres).
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: SPA.2010.3.2-04 | Award Amount: 651.37K | Year: 2011
The development of secure and re-usable re-entry vehicle requires the complete control of the heat distribution on its Thermal Protection System (TPS). During the most critical re-entry phase, the hypersonic flow along the vehicle initiates a laminar boundary layer inside of which most of the transfer phenomena take place (heat, momentum and mass transfer). If at one position of the vehicle, this boundary layer experiences a transition from the laminar to the turbulent regime then at the corresponding position the TPS will receive a sharp increase of the incoming heat flux (minimum 3 times higher). If the vehicle aims to be re-usable, it is mandatory to protect it adequately against this overheat. Therefore Aerospace designer needs to receive the proper information and tools allowing a better prediction and ultimately a better control of the transition in hypersonic regime. This activity proposes a detailed and careful experimental and numerical data base from six hypersonic facilities and several numerical codes from EU and Russia. The selected configuration will be the one of a sharp cone. The noise level in each facility will be characterised. The probable differences between facility predictions running at seemingly comparable conditions (Mach number, Reynolds number and model dimensions) will be explained. Various types of numerical simulations including DNS will be carried out to prepare the experimental campaigns. These simulations will be further validated and assess during the activity. Hypersonic transition will be observed with and without localized control. A deeper understanding of the physics involved in hypersonic transition will be investigated. The challenging solution of the local thermal control of the boundary layer at hypersonic regime will be proposed for future aerospace mission and disseminated in the industrial community.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: AAT.2010.1.1-1.;AAT.2010.4.1-1. | Award Amount: 3.62M | Year: 2011
The RECEPT project will deliver upstream aerodynamics research that will contribute (i) to the drive to strengthen the competitiveness of European manufacturing industry, (ii) to the need to improve the environmental impact of aircraft with regards to emissions. Within the RECEPT project, knowledge about transition phenomena and theoretical/numerical tools obtained during the last 50 years since the eN method was proposed, are used to develop the next generation transition prediction methods. The new method will be an amplitude-based prediction method incorporating true effects of the disturbance environment of the incoming flow, the so called receptivity process, as well as knowledge about actual amplitudes at which disturbances breakdown to turbulence. This will largely remove the need for empirical correlations and render possible accurate prediction of the onset of transition both under wind tunnel and free-flight conditions. Proposed research activities within RECEPT project will also contribute to design of more advanced transition control devices. Consequently, it will contribute to achieving the objectives for technology readiness to reduce fuel consumption and hence emissions. It directly addresses the topic of AAT.2010.1.1.1, AAT.2010.4.1.1 and AAT.2010.4.2.1. The RECEPT consortium consists of 12 organisations from 4 different member states (Sweden, Italy, France Germany) and one of International Cooperation Partner Countries, Russia. It contains 3 aircraft manufacturers (Airbus, SAAB, Piaggio), 5 research organisations (CIRA, DLR, FOI, ITAM, ONERA) and 4 universities (Kungliga Teknika Hgskolan, Universit di Genova, Universit di Salerno, Universitt Stuttgart). Participation of industry will directly transfer the new knowledge and greatly improved method to the more applied work to be performed within the Joint Technology Initiative Clean Sky.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: AAT.2010.1.1-1.;AAT.2010.1.1-3. | Award Amount: 5.10M | Year: 2012
Vision-2020, whose objectives include the reduction of emissions and a more effective transport systems, puts severe demands on aircraft velocity and weight. These require an increased load on wings and aero-engine components. The greening of air transport systems means a reduction of drag and losses, which can be obtained by keeping laminar boundary layers on external and internal airplane parts. Increased loads make supersonic flow velocities more prevalent and are inherently connected to the appearance of shock waves, which in turn may interact with a laminar boundary layer. Such an interaction can quickly cause flow separation, which is highly detrimental to aircraft performance, and poses a threat to safety. In order to diminish the shock induced separation, the boundary layer at the point of interaction should be turbulent. The main objective of the TFAST project is to study the effect of transition location on the structure of interaction. The main question is how close the induced transition may be to the shock wave while still maintaining a typical turbulent character of interaction. The main study cases - shock waves on wings/profiles, turbine and compressor blades and supersonic intake flows - will help to answer open questions posed by the aeronautics industry and to tackle more complex applications. In addition to basic flow configurations, transition control methods (stream-wise vortex generators and electro-hydrodynamic actuators) will be investigated for controlling transition location, interaction induced separation and inherent flow unsteadiness. TFAST for the first time will provide a characterization and selection of appropriate flow control methods for transition induction as well as physical models of these devices. Emphasis will be placed on closely coupled experiments and numerical investigations to overcome weaknesses in both approaches.
Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: SPA.2010.3.2-04 | Award Amount: 690.53K | Year: 2011
The main objective of the study is the experimental and numerical study of gas surface interaction phenomena in the high enthalpy flow field behind the bow shock in front of a model at Martian entry flow conditions. The improvement of physical modelling using experimental data and its implementation into the CFD codes is essential to understand and interpret the physical processes. At the end the project will allow to estimate the aerothermal loads on the vehicle more accurately. Main activities of the project are: -Definition of requirements on experiments, modelling and CFD codes using realistic Mars mission profiles -Experiments on the measurement of flow parameters in the free stream and behind the shock and stagnation point heat flux rate -Improvement of existing physical models with respect to the non-equilibrium effects, transport properties and gas surface interaction chemistry -Implementation of improved physical models into the CFD codes and simulation of experiments -Synthesis of the data and extrapolation to the flight
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: AAT.2013.8-1. | Award Amount: 3.21M | Year: 2013
BUTERFLI is a project in response to the invitation to tender from European Commission FP7 within Call FP7-AAT-2013 RTD-Russia. BUTERFLI is the acronym of BUffet and Transition delay control investigated within Europe-Russia cooperation for improved FLIght performances. The Project Topic will focus on experimental and numerical flow control investigations of different phenomena: the buffet on a laminar airfoil, the buffet on a turbulent supercritical airfoil, and the cross-flow instabilities on a swept wing. Different control techniques will be studied: bump design, fluidic control devices, and DBD devices. The Project aims at the improvement of aircraft flight performances. This Project will be carried out in the framework of a EUROPE RUSSIA cooperation. ONERA is the coordinator, and TSAGI will act as Coordinator of the Russian Parties. There are 12 partners, 7 from Europe and 5 from Russia. ONERA (F), IAG-Stuttgart (G), DLR (G), KTH (S), University of Nottingham (UK), EADS UK Ltd. (UK), TsAGI (Russia), MIPT (Russia), JIHT (Russia), ITAM (Russia), Sukhoi Civil Aircraft (Russia), and Erdyn (F). BUTERFLI is splitted into four work packages: WP1 is dedicated to buffet control on 2D turbulent supercritical wing (tangential jet blowing and plasma actuators) WP2 is dedicated to buffet control on 2D laminar wing (bump and perforation blowing) WP3 is dedicated to crossflow instabilities control on swept wing WP4 ensures the scientific coordination of the overall project, and will proposes final roadmaps for the future.
Agency: European Commission | Branch: FP7 | Program: CP-FP | Phase: SPA.2011.3.2-02 | Award Amount: 11.78M | Year: 2011
The QB50 Project will demonstrate the possibility of launching a network of 50 CubeSats built by CubeSat teams from all over the world to perform first-class science and in-orbit demonstration in the largely unexplored middle and lower thermosphere. Space agencies are not pursuing a multi-spacecraft network for in-situ measurements in the middle and lower thermosphere because the cost of a network of 50 satellites built to industrial standards would be very high and not justifiable in view of the limited orbital lifetime. No atmospheric network mission for in-situ measurements has been carried out in the past or is planned for the future. A network of satellites for in-situ measurements in the middle and lower thermosphere can only be realised by using very low-cost satellites, and CubeSats are the only realistic option. The Project will demonstrate the sustained availability of a low-cost launch opportunities, for launching small payloads into low-Earth orbit; these could be microsatellites or networks of CubeSats or nanosats or many individual small satellites for scientific, technological, microgravity or biology research. The Project will include the development of a deployment system for the deployment into orbit of a large number of single, double or triple CubeSats. Once the system is developed for QB50 it can be easily adapted to other missions. QB50 will also provide a launch opportunity for key technology demonstration on IOD CubeSats such as formation flying and aerobrakes. All 50 CubeSats will be launched together into a circular orbit at approximately 380 km altitude. Due to atmospheric drag, the orbits of the CubeSats will decay and progressively lower and lower layers of the thermosphere will be explored without the need for on-board propulsion, perhaps down to 200 km. QB50 will be among the first CubeSat networks in orbit.