Browsing by Author "Goman, M. (Mikhail G.)"

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    Adaptive runge-kutta discontinuous galerkin method for complex geometry problems on cartesian grid
    (Wiley, 2013) Liu, Jianming; Qiu, Jianxian; Hu, Ou; Zhao, Ning; Goman, M. (Mikhail G.); Li, X. K.
    A Cartesian grid method using immersed boundary technique to simulate the impact of body in fluid has become an important research topic in computational fluid dynamics because of its simplification, automation of grid generation, and accuracy of results. In the frame of Cartesian grid, one often uses finite volume method with second order accuracy or finite difference method. In this paper, an h-adaptive Runge–Kutta discontinuous Galerkin (RKDG) method on Cartesian grid with ghost cell immersed boundary method for arbitrarily complex geometries is developed. A ghost cell immersed boundary treatment with the modification of normal velocity is presented. Themethod is validated versus well documented test problems involving both steady and unsteady compressible flows through complex bodies over a wide range of Mach numbers. The numerical results show that the present boundary treatment to some extent reduces the error of entropy and demonstrate the efficiency, robustness, and versatility of the proposed approach.
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    Aerodynamic model development and simulation of airliner spin for upset recovery
    (EDP Sciences, 2013-06) Khrabrov, A. N. (Alexander N.); Sidoryuk, M. E. (Maria E.); Goman, M. (Mikhail G.)
    The aerodynamic model of a generic airliner configuration is developed for a wide range of angles of attack, sideslip and angular rate based on experimental data obtained in wind tunnels using static, forced oscillations and rotary balance tests. The developed aerodynamic model is applied for the investigation of the airliner scaled model nonlinear dynamics at high angles of attack with an intensive rotation to identify potential spin modes and spin recovery procedures. The evaluated equilibrium spin parameters and simulated recovery control deflections are in good agreement with the experimental results from free-spin tests obtained in the TsAGI vertical wind tunnel. The work is performed in connection with the European FP7 project SUPRA (Simulation of UPset Recovery in Aviation, www.supra.aero).
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    Aerodynamic model of transport airplane in extended envelope for simulation of upset recovery
    (ICAS 2012 CD-ROM PROCEEDINGS, 2012-09) Abramov, Nikolay; Goman, M. (Mikhail G.); Khrabrov, A. N. (Alexander N.); Kolesnikov, E. N.; Sidoryuk, M. E. (Maria E.); Soemarwoto, B.; Smaili, H.
    The paper presents the aerodynamic model in extended flight envelope for a generic airliner with under wing engines and conventional tail developed within the EU Framework Programme (FP7) research project Simulation of Upset Recovery in Aviation (SUPRA) (www.supra.aero). The SUPRA aerodynamic model is covering angles of attack beyond stall and speeds from take-off to cruise flight. The aerodynamic model in extended flight envelope developed for piloted simulation of upset prevention and recovery has been successfully validated by a number of expert pilots.
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    Aerodynamic Modeling for Post-Stall Flight Simulation of a Transport Airplane
    (American Institute of Aeronautics and Astronautics (AIAA), 2019-04-09) Abramov, Nikolay; Goman, M. (Mikhail G.); Khrabrov, A. N. (Alexander N.); Soemarwoto, B.
    The principles of aerodynamic modeling in the extended flight envelope, which is characterized by the development of separated flow, are outlined and illustrated for a generic transport airplane. The importance of different test techniques for generating wind tunnel data and the procedure for blending the obtained experimental data for aerodynamic modeling are discussed. Complementary use of computational fluid dynamics simulations reveals a substantial effect of the Reynolds number on the intensity of aerodynamic autorotation, which is later reflected in the aerodynamic model. Validation criteria for an extended envelope aerodynamic model are discussed, and the important role of professional test pilots with post-stall flying experience in tuning aerodynamic model parameters is emphasized. The paper presents an approach to aerodynamic modelling that was implemented in the project Simulation of Upset Recovery in Aviation (2009–2012), funded by the European Union under the seventh framework programme. The developed post-stall aerodynamic model of a generic airliner configuration for a wide range of angles of attack, sideslip, and angular rate was successfully validated by a number of professional test pilots on hexapod and centrifuge-based flight simulator platforms.
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    Aircraft dynamics at high incidence flight with account of unsteady aerodynamic effects.
    (2004-08-16) Abramov, Nikolay; Goman, M. (Mikhail G.); Khrabrov, A. N. (Alexander N.)
    An adequate modelling of nonlinear and unsteady aerodynamics at high incidence flight is important for design of future agile and stealth fighters as well as for improved prediction of high angle of attack dynamics of normal aircraft configurations. The limitations for conventional aerodynamic model based on aerodynamic derivatives concept are analyzed considering the longitudinal motion of a hypothetical aircraft with the 65 degree delta wing and thrust vectoring control. The dynamic unsteady aerodynamic model approximating the vortical and separated flow time lag effects is considered along with the conventional aerodynamic model and their impact on aircraft dynamics and control law design is discussed.
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    Analysis of Aircraft Nonlinear Dynamics Using Non-Gradient Based Numerical Methods and Attainable Equilibrium Sets
    (2012) Kolesnikov, E. N.; Goman, M. (Mikhail G.)
    Multiple equilibrium solutions of aircraft motion equation are investigated using non-gradient based numerical methods and computation of attainable equilibrium sets. The proposed approach may be applied to realistic industrial scale aircraft aerodynamic models based on look-up data tables. Advantages of this method and its joint use with predictor-corrector techniques for continuation and bifurcation analysis of aircraft nonlinear dynamics are discussed. A number of computational examples for aircraft dynamics investigation are presented for a generic airliner aerodynamic model developed within the SUPRA research project – “Simulation of Upset Recovery in Aviation” – funded by the European Union 7th Framework Program.
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    Bifurcation control of aeroelastic limit cycle oscillations
    (IFAC-PapersOnLine Elsevier, 2009-06) Demenkov, Maxim; Goman, M. (Mikhail G.)
    An active flutter suppression using linear saturated control is investigated for a 2dof wing section with nonlinear torsional stiffness and limited deflection amplitude of its single control effector. The suppression of limit cycle oscillations in the nonlinear closed-loop system is achieved through maximization of the stability region of the linearized system. A bifurcation sequence leading to limit cycle disappearance is revealed. With increase of the maximum control input amplitude, the closed-loop limit cycle is transformed into a stable torus, which disappears at higher control amplitude through a nonlocal bifurcation similar to a boundary crisis in chaotic systems. Finally, a saddle-node bifurcation of the limit cycle gives necessary conditions for global stability in the closed-loop system.
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    Chaotic dynamics in a simple aeromechanical system.
    (Horwood Publishing Ltd, 2002) Goman, M. (Mikhail G.); Khrabrov, A. N. (Alexander N.); Khramtsovsky, A.N
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    Characterisation of wind tunnel observed, large-amplitude pitch limit-cycles
    (American Institute of Aeronautics and Astronautics, AIAA, 2011-09) Pattinson, J.; Lowenberg, M. H.; Goman, M. (Mikhail G.)
    A five-degree-of-freedom dynamic wind tunnel rig is used in the observation of large amplitude self-sustaining pitch oscillations of a model aircraft. These oscillations arise during a quasi-steady ramp input to the aircraft model’s elevator surfaces in one-degree-of-freedom pitch mode and in the longitudinal two-degree-of-freedom pitch and heave modes. A mathematical model of the aerodynamics, incorporating dynamic stall, is proposed. The model is coupled to the equations of motion of the rig, which include terms for friction, and fitted to the experimental data. This later process is achieved using continuation and bifurcation analysis and revealed the influence of friction forces on the oscillatory behavior. The quality of the fit and the use of a phenomenological model allows a possible cause for these oscillations to be proposed.
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    Computation of controllability regions for unstable aircraft dynamics.
    (American Institute Aeronautics and Astronautics, 2004-01-01) Goman, M. (Mikhail G.); Demenkov, M. N. (Max)
    An active control approach to air vehicle design can significantly expand the flight envelope and improve vehicle performance characteristics. In some cases it can be attained by implementing the aerodynamically unstable configuration or expanding operation at flight regimes with dynamic instability, which are then purposely stabilized by the flight control system. An important issue in stabilization of unstable dynamics is connected with the size of the controllability region, which is the set of all states of the aircraft dynamics that can be stabilized by some realizable control action. This region is bounded because of nonlinear actuator constraints, and its size can be considered as a measure for allowable level of external disturbances. In this paper an algorithm based on convex optimization technique is proposed for computation of the controllability region of an unstable linear system under amplitude and rate control constraints. Examples of the controllability region analysis for an aeroservoelastic airfoil system and unstable aircraft dynamics are presented to illustrate the capabilities of the proposed algorithm.
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    Computational framework for investigation of aircraft nonlinear dynamics.
    (Elsevier, 2007-05-21) Goman, M. (Mikhail G.); Khramtsovsky, A. V. (Andrew V.)
    A computational framework based on qualitative theory, parameter continuation and bifurcation analysis is outlined and illustrated by a number of examples for inertia-coupled roll maneuvers. The focus is on the accumulation of computed results in a special database and its incorporation into the investigation process. Ways to automate the investigation of aircraft nonlinear dynamics are considered.
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    Computational Ground Effect Aerodynamics and Airplane Stability Analysis During Take-off and Landing
    (EUCASS, 2017-09-22) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)
    Computational simulations of aerodynamic characteristics of the Common Research Model (CRM), representing a typical transport airliner, are conducted using CFD methods in close proximity to the ground. The obtained dependencies on bank angle for aerodynamic forces and moments are further used in stability and controllability analysis of the lateral-directional aircraft motion. Essential changes in the lateral-directional modes in close proximity to the ground have been identified. For example, with approach to the ground, the roll subsidence and spiral eigenvalues are merging creating the oscillatory Roll-Spiral mode with quite significant frequency. This transformation of the lateral-directional dynamics in piloted simulation may affect the aircraft responses to external crosswind, modify handling quality characteristics and improve realism of crosswind landing.
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    Computational Simulation of Airfoils Stall Aerodynamics at Low Reynolds Numbers
    (Royal Aeronautical Society, Applied Aerodynamics Conference, 2016-07-19) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)
    Experimental results for aerodynamic static hysteresis at stall conditions obtained in the TsAGI's T-124 low-turbulence wind tunnel for NACA0018 are presented and analysed. Computational predictions of aerodynamic static hysteresis are made using the OpenFOAM simulations considering di erent grids, turbulence models and solvers. Comparisons of compu- tational simulation results with experimental wind tunnel data are made for 2D NACA0018 and NACA0012 airfoils at low Reynolds numbers Re = (0.3-1.0) millions. The properties of the proposed phenomenological bifurca- tion model for simulation of aerodynamic loads at the existence of static hysteresis are discussed.
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    Design and analysis of combined nonlinear dynamic inversion and H_infty-based flight contol laws
    (Zhejiang University, China, 2010-05) Sidoryuk, M. E. (Maria E.); Kolesnikov, E. N.; Fan, Y.M.; Goman, M. (Mikhail G.)
    There is a significant interest in developing flight control laws which need minimum gain scheduling across the whole flight envelope while providing required robust performance and stability properties to the closed-loop system. Dynamic inversion and/or feedback linearization technique are considered by many authors as candidates to achieve these objectives. A common feature of proposed solutions is that dynamic inversion via nonlinear control feedbacks compensates coupled nonlinear aircraft dynamics and then the desired command response is prescribed by external robust linear feedback controller. The main advantage of the method is that control laws automatically achieve decoupling of command variables and avoid extensive gain scheduling. In this paper a combined two-loop design approach is implemented. An inner loop NDI-based controller is designed to linearize the dynamics and then a outer loop feedback controller designed using H_infty-based methods is applied to the resulting system to ensure robustness to model uncertainties. To achieve a more practical design solution both stability and performance characteristics are analyzed depending on roles assigned for inner and outer loop controllers. Robustness stability analysis is performed using mu-analysis, LPV (Linear Parameter Varying) methods and classical stability margins. The ultimate goal is to achieve a relatively simple design process providing robust performance and stability guarantees.
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    Effect of Control Constraints on Active Stabilization of Flutter Instability
    (Cambridge Scientific Publishers Ltd, 2009) Vikhorev, K.; Demenkov, M. N. (Max); Goman, M. (Mikhail G.)
    The effect of amplitude and rate control constraints in active flutter suppression was analysed for a number of different linear and nonlinear control laws considering mathematical model of two degree-of freedom aeroelastic airfoil system with trailing and leading edge flaps. The LQR control law providing maximum region of attraction for the linearized system under amplitude control constraints was investigated taking into account a structural nonlinearity and actuator rate constraints. The region of attraction of a stabilized equilibrium was used as a metric to identify a set of linear control laws providing practically global stabilization of flutter instability with account of structural nonlinearities and rate control constraints. The eigenstructure assignment method was implemented for control law design considering trailing edge flap or a combination of leading and trailing edge flaps.
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    Evaluation of Aerodynamic Characteristics in Oscillatory Coning Using CFD Methods
    (EUCASS, 2022-09-28) Sereez, Mohamed; Goman, M. (Mikhail G.)
    The wind tunnel rotary-balance testing is widely used in aircraft dynamics to characterise aerodynamics at moderate and high angles of attack during stall and spin regimes. In such experiments an aircraft test model is rotated along the wind-tunnel free-stream velocity vector allowing the measurement of aerodynamic characteristics in steady rotational flow conditions with constant angle of attack and sideslip. In modified tests named as oscillatory coning, the rotation vector is tilted from the free-stream velocity vector making flow conditions with periodic variations in angle of attack and sideslip. This allows evaluation of unsteady aerodynamic responses superimposed on steady conical rotation. The use of CFD methods for prediction of aerodynamic characteristics in rotary-balance and oscillatory coning conditions may significantly complement experimental data via extrapolation of data for higher Reynolds numbers, elimination of interference effects from supporting system, extraction of unsteady aerodynamic derivatives affecting aircraft dynamic stability. This paper presents CFD simulation results obtained in rotary-balance and oscillatory coning motions for the NASA Common Research Model (CRM) in its wing-body configuration at moderate 𝑅𝑒 = 1 × 10^6 , low Mach number 𝑀=0.2 and the use of the obtained unsteady responses in aerodynamic modelling.
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    Evaluation of Aircraft Model Upset Behaviour Using Wind Tunnel Manoeuvre Rig
    (AIAA Atmospheric Flight Mechanics Conference, 2015-01) Araujo-Estrada, Sergio A.; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.)
    This paper discusses the development of a novel multi-degree-of-freedom dynamic manoeuvre rig aimed at investigation of aircraft upset/LOC-related behaviour in the wind tunnel. The motivation behind the development and characteristics of the rig are first described, along with example behaviour of an aircraft model exhibiting nonlinear time-dependent aerodynamics in an open-jet low-speed wind tunnel. Test objectives for assessment of upset onset scenarios - both for parameter estimation purposes and to 'physiccally simulate' the behaviour - are then described, as is the design of the upgraded instrumentation system to facilitate experimental investigation. Finally, examples of relevant behaviour involving real-time control of the rig to explore nonlinear conditions leading to upset are presented; these are evaluated in terms of prospects for such testing in aircraft development and analysis projects.
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    Evaluation of aircraft performance and maneuverability by computation of attainable equilibrium sets.
    (American Institute of Aeronautics and Astronautics, 2008) Goman, M. (Mikhail G.); Khramtsovsky, A. V. (Andrew V.); Kolesnikov, E. N.
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    Experimental investigation of aerodynamic hysteresis using a 5-DoF wind tunnel manoeuvre rig
    (AIAA, 2019-01-11) Gong, Z.; Araujo-Estrada, Sergio A.; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.)
    The high-incidence aerodynamics of a lightweight jet trainer aircraft model has been investigated using a novel five-degree-of-freedom (DOF) dynamic maneuver rig, recently updated with improved actuation and data acquisition systems, in the 7 × 5 ft closed-section low-speed wind tunnel at the University of Bristol. The major focus was to identify the nonlinear and unsteady aerodynamic characteristics specific to the stall region and which affect free-to-move aircraft-model behavior. First, the unstable equilibrium states in the limit-cycle regions were stabilized, and so observed, over a wide range of angles of attack using a simple elevator feedback control lawbased on pitch angle and pitch-rate sensor measurements. Tests with two DOF, namely, the aircraft model and rig-arm pitch angles, revealed the existence of static hysteresis in the normal force acting on the aircraft model in the stall region. Unlocking the aircraft model in roll and yaw accompanied by feedback stabilization of the lateral–directional modes of motion demonstrated the onset of asymmetric aerodynamic rolling and yawing moments in this four-DOF configuration. This observation implicitly indicates a link between the static hystereses in the normal aerodynamic force with an onset of aerodynamic asymmetry. The experimental results show the efficiency of the updated multi-DOF actively controlled maneuver rig in providing insight into complicated aerodynamic effects within the stall region.
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    Final results of the supra project: Improved Simulation of Upset Recovery
    (2012) Fucke, Lars; Groen, E.; Goman, M. (Mikhail G.); Abramov, Nikolay; Wentink, M.; Nooij, Suzanne; Zaichik, L.