Time filter

Source Type

Cesenek J.,Charles University | Cesenek J.,Aerospace Research and Test Establishment | Feistauer M.,Charles University | Kosik A.,Charles University
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2013

The subject of the paper is the numerical simulation of the interaction of two-dimensional compressible viscous flow and a vibrating airfoil. A solid airfoil with two degrees of freedom performs rotation around an elastic axis and oscillations in the vertical direction. The numerical simulation consists of the solution of the Navier-Stokes system by the discontinuous Galerkin method coupled with a system of nonlinear ordinary differential equations describing the airfoil motion. The time-dependent computational domain and a moving grid are taken into account by the arbitrary Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equations. The developed method is robust with respect to the magnitude of the Mach number and Reynolds number. Its applicability is demonstrated by numerical experiments. The subject of the paper is the numerical simulation of the interaction of two-dimensional compressible viscous flow and a vibrating airfoil. A solid airfoil with two degrees of freedom performs rotation around an elastic axis and oscillations in the vertical direction. The numerical simulation consists of the solution of the Navier-Stokes system by the discontinuous Galerkin method coupled with a system of nonlinear ordinary differential equations describing the airfoil motion. The time-dependent computational domain and a moving grid are taken into account by the arbitrary Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equations. The developed method is robust with respect to the magnitude of the Mach number and Reynolds number. Its applicability is demonstrated by numerical experiments. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Kral M.,Aerospace Research and Test Establishment | Kral M.,Czech Technical University | Cabrnoch B.,Aerospace Research and Test Establishment | Holy S.,Czech Technical University
Materials Today: Proceedings | Year: 2016

The use of fiber reinforced composites for structural components requires reliable knowledge of their damage and failure behavior. Damage mechanisms of fiber composites subjected to static loading are satisfactory described and the determination of safety margins is usually feasible. In the case of composite structures subjected to cyclic loading the situation is rather complicated. In comparison with metals fatigue behavior of composites is affected by many damage modes dependent on stress level, loading frequency, number of cycles and others. Among the outer signs of fatigue damage particularly important for engineers can be included reduction of stiffness and strength. The main goal of this paper is to describe proposed stiffness reduction model with the focus on the identification of model coefficients on the basis of unidirectional tensile experiments. © 2016 Elsevier Ltd.


Straka P.,Aerospace Research and Test Establishment | Prihoda J.,Czech Institute of Thermomechanics
EPJ Web of Conferences | Year: 2016

The contribution deals with the simulation of the laminar/turbulent transition taking into account the effect of wall roughness. The correlation for the transition onset proposed by Straka and Příhoda [1] was modified for the effect of the wall roughness using the correlation according to Boyle and Stripf [2]. This correlation derived for the wall roughness formed by regularly distributed truncated cones was modified for flows over the distributed wall roughness. The algebraic transition model proposed by Straka and Příhoda [1] with the modified relation for the transition onset was verified by means of the incompressible flat-plate boundary-layer and the compressible flow through the turbine blade cascade with rough blades. © 2016 Owned by the authors, published by EDP Sciences.


Cesenek J.,Aerospace Research and Test Establishment
EPJ Web of Conferences | Year: 2014

In this paper we deal with numerical simulation of the compressible viscous flow. The mathematical model of flow is represented by the system of non-stationary compressible Navier-Stokes equations. This system of equations is discretized by the discontinuous Galerkin finite element method in space and in time using piecewise polynomial discontinuous approximations. We present some numerical experiments to demonstrate the applicability of the method using own-developed code. © 2014 EDP Sciences.


Vrchota P.,Aerospace Research and Test Establishment | Prachar A.,Aerospace Research and Test Establishment
33rd AIAA Applied Aerodynamics Conference | Year: 2015

NASA CRM has been used for evaluation of the effect aeroelasticity on aerodynamic forces and local flowfield. A CFD analysis of the rigid model showed large differences between the CFD and experimental data. It was observed that the model deformation has significant effect on the aerodynamic characteristics. The on-line mesh deformation on basis of a wing modal analysis was used to improve accuracy of CFD results. Twenty modes in total were used during coupled CFD simulations. The results from this simulations showed that adding the wing deformation into the CFD simulation did improve the accuracy of obtained aerodynamic coefficients. The same methodology has been applied to the full model configuration considering the deformation of all parts of the model. The results from the CFD analyses with on-line mesh deformation of the semi-span and full model are the focus of this paper. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved.


Prachar A.,Aerospace Research and Test Establishment
Acta Polytechnica | Year: 2016

Data obtained from an experimental simulation on a new test rig for axial fans are compared to a CFD simulation. The Edge solver is used and the development needed for the simulation (boundary conditions, free stream consistency) is described. Adequate agreement between the measured and calculated data is observed. © Czech Technical University in Prague, 2016.


Cesenek J.,Aerospace Research and Test Establishment
EPJ Web of Conferences | Year: 2016

In this article we deal with numerical simulation of the non-stationary compressible turbulent flow. Compressible turbulent flow is described by the Reynolds-Averaged Navier-Stokes (RANS) equations. This RANS system is equipped with two-equation k-omega turbulence model. These two systems of equations are solved separately. Discretization of the RANS system is carried out by the space-time discontinuous Galerkin method which is based on piecewise polynomial discontinuous approximation of the sought solution in space and in time. Discretization of the two-equation k-omega turbulence model is carried out by the implicit finite volume method, which is based on piecewise constant approximation of the sought solution. We present some numerical experiments to demonstrate the applicability of the method using own-developed code. © 2016 Owned by the authors, published by EDP Sciences.


Simak J.,Aerospace Research and Test Establishment | Michalek J.,Aerospace Research and Test Establishment
EPJ Web of Conferences | Year: 2016

This paper is concerned with a cooling system for inlet guide vanes of a small turbine engine which are exposed to a high temperature gas leaving a combustion chamber. Because of small dimensions of the vanes, only a simple internal cavity and cooling holes can be realized. The idea was to utilize a film cooling technique. The proposed solution was simulated by means of a numerical method based on a coupling of CFD and heat transfer solvers. The numerical results of various scenarios (different coolant temperature, heat transfer to surroundings) showed a desired decrease of the temperature, especially on the most critical part - the trailing edge. The numerical data are compared to results obtained by experimental measurements performed in a test facility in our institute. A quarter segment model of the inlet guide vanes wheel was equipped with thermocouples in order to verify an effect of cooling. Despite some uncertainty in the results, a verifiable decrease of the vane temperature was observed. © 2016 Owned by the authors, published by EDP Sciences.


Pick P.,Aerospace Research and Test Establishment
EPJ Web of Conferences | Year: 2015

The present contribution summarizes the power efficiency of the active flow control of the boundary layer of air around a hump. The synthetic jet generator with a rectangular output part, i.e. a slot, is actuated using a modulated signal. The actuation of the synthetic jet is carried out by modulating the input voltage of acoustic transducers of the generator. This causes the decrease of the loss coefficient and the change of the mixing size area (e.g. wake). A comparison of three types of modulating signals and their influence on the loss coefficient is performed. The main advantages of modulated signal are then described. © 2015 Owned by the authors, published by EDP Sciences.


Podzimek J.,Aerospace Research and Test Establishment
Engineering Against Failure - Proceedings of the 3rd International Conference of Engineering Against Failure, ICEAF 2013 | Year: 2013

Today's higher requirements for environmental friendly solutions force manufacturers to look for alternatives. One of them was the replacement of a lead sealing in an aerial turboprop engine with a polytetrafluoroethylene (PTFE) alternative. The task was to bond steel and PTFE and to make a durable bond under different temperature conditions. There were certain difficulties due to the mechanical and chemical properties of PTFE, and this lecture describes the evolution from submission through testing towards the solution of this problem, as well as some basic design ideas and principles.

Loading Aerospace Research and Test Establishment collaborators
Loading Aerospace Research and Test Establishment collaborators