Browsing by Author "Abramov, Nikolay"
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Item Metadata only Aerodynamic model of transport airplane in extended envelope for simulation of upset recovery(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.Item Open Access Aerodynamic Modeling for Post-Stall Flight Simulation of a Transport Airplane(American Institute of Aeronautics and Astronautics, 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.Item Metadata only 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.Item Open Access 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.Item Open Access Computational Simulation of Airfoils Stall Aerodynamics at Low Reynolds Numbers(Royal Aeronautical Society, 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.Item Metadata only 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.Item Metadata only Flight Envelope Expansion via Active Control Solutions for a Generic Tailless Aircraft(2014-09-07) Abramov, Nikolay; Bommanahal, Mallesh; Chetty, S.; Goman, M. (Mikhail G.); Kolesnikov, E. N.; Murthy, P V SatyanarayanaAircraft dynamics at high angles of attack due to loss of stability and control essentially limits its manoeuvrability. Modern control systems implement flight envelope protection at the cost of maneuverability to improve safety in these conditions. Flight envelope boundaries, which are set taking into account deterioration of stability and controllability due to separated flow, can be expanded by appropriate design of control laws. However, such a design requires extensive analysis of the maneuver envelope of the airframe and its utilization by the flight envelope protection laws. The reliability of this analysis depends on the adequate aerodynamic modeling which captures nonlinear unsteady variation of aerodynamic loads in these flight regimes. Two novel models for unsteady aerodynamics at low and high subsonic Mach numbers are described. These models and prototyping control laws are used for closed loop computational analysis. The computational methodology of clearing flight control laws for flight envelope expansion of a Generic Tailless Aircraft (GTA) is addressedItem Open Access Impact of Ground Effect on Airplane Lateral Directional Stability during Take-Off and Landing(Scientific Research Publishing, 2018-01) 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. The material of this paper was presented at the Seventh European Conference for Aeronautics and Space Sciences EUCASS-2017. Further work is carried out for evaluation of the ground effect aerodynamics for a high-lift configuration based on a hybrid geometry of DLR F11 and NASA GTM models with fully deployed flaps and slats. Some aspects of grid generation for a high lift configuration using structured blocking approach are discussed.Item Open Access Investigation of Aerodynamic Characteristics of a Generic Transport Aircraft in Ground Effect Using URANS Simulations(Royal Aeronautical Society, 2022-09-14) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)This paper focuses on computational prediction of aerodynamic and the flow field characteristics for NASA Common Research Model (CRM) in it’s High-Lift (HL) configuration in close proximity to the ground. The URANS simulation with the Spalart-Allmaras (SA) turbulence model is checked for the quality of the generated mesh and compared with the available wind tunnel data. The obtained simulation results in the immediate vicinity of the ground demonstrate significant changes in the longitudinal and lateral-directional aerodynamic characteristics in aircraft banked positions, which is important for a better understanding of aircraft landing in crosswind conditions.Item Metadata only Investigation of Attainable Equilibrium Sets for Clearance of Flight Control Laws(American Institute of Aeronautics and Astronautics, 2010-01) Abramov, Nikolay; Goman, M. (Mikhail G.); Kolesnikov, E. N.; Sidoryuk, M. E. (Maria E.)A systematic investigation of aircraft equilibrium states and their local stability characteristics is used for clearance of flight control laws for a large variety of manoeuvres. The proposed approach is illustrated by clearance of the LPV control laws designed in a wide subsonic region for the F-18HARV aircraft in level flight conditions and clearance of the F-16 aircraft longitudinal and lateral-directional stability augmentation system for high range of incidence and intensive velocity roll rotation.Item Open Access Modelling of unsteady aerodynamic characteristics for aircraft dynamics applicationsat high incidence flight(De Montfort University, 2005) Abramov, NikolayItem Open Access A modified dual time integration technique for aerodynamic quasi-static and dynamic stall hysteresis(Sage, 2023-03-29) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)Simulation of the aerodynamic stall phenomenon in both quasi-static and dynamic conditions requires expensive computational resources. The computations become even more costly for static stall hysteresis using an unsteady solver with very slow variation of angle of attack at low reduced frequencies. In an explicit time-marching solver that satisfies the low Courant number condition, that is, CFL<1, the computational cost for such simulations becomes prohibitive, especially at higher Reynolds numbers due to the presence of thin-stretched cells with large aspect ratio in the boundary layer. In this paper, a segregated solver method such as the Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) is modified as a dual pseudo-time marching method so that the unsteady problem at each time step is reformulated as a steady state problem. The resulting system of equations in the discretized finite volume formulation is then reduced to zero or near-zero residuals using available convergence acceleration methods such as local time stepping, multi-grid acceleration and residual smoothing. The performance and accuracy of the implemented algorithm was tested for three different airfoils at low to moderate Reynolds numbers in both incompressible and compressible flow conditions covering both attached and separated flow regimes. The results obtained are in close agreement with the published experimental and computational results for both quasi-static and dynamic stall and have demonstrated significant savings in computational time.Item Metadata only Prediction of aerodynamic characteristics of high-lift Common Research Model in ground effect(Cambridge University Press, 2023-10-20) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)Reynolds Averaged Navier-Stokes (RANS) simulations are performed to investigate the aerodynamic characteristics of the NASA Common Research Model (CRM) in its high-lift (HL) configuration in close proximity to the ground. The RANS simulations are conducted at a moderate Reynolds number of Re=5.49×106 and M=0.2 with the use of the Spalart-Allmaras (SA) turbulence model. out of ground effect (OGE) simulation results are validated against available wind tunnel data before proceeding to in ground effect (IGE) simulations. The obtained computational results in the immediate vicinity of the ground with asymmetric aircraft attitudes demonstrate significant changes in the longitudinal and lateral-directional aerodynamic characteristics, which should be taken into account in flight dynamics analysis of aircraft during take-off and landing in crosswind conditions.Item Open Access Prediction Of Static Aerodynamic Hysteresis On A Thin Airfoil Using OpenFOAM(American Institute of Aeronautics and Astronautics, 2020-10-13) Sereez, Mohamed; Abramov, Nikolay; Goman, M. (Mikhail G.)The paper presents computational prediction of aerodynamic hysteresis loops in static conditions for a two-dimensional aerofoil that was used as a cross-section profile for a rectangular wing with an aspect ratio of five, tested in the TsAGI T-106 wind tunnel at a Reynolds number of 𝑅𝑒=6×106 and a Mach number of 𝑀=0.15. Tests in the wind tunnel showed that minor changes in the curvature of the leading edge of the thin aerodynamic profile lead to a significant increase in the maximum lift coefficient when significant hysteresis loops appear in the aerodynamic characteristics of the wing. The computational predictions of stall aerodynamics presented in this paper are made for a two-dimensional profile using the OpenFOAM open-source code to simulate a flow based on the unsteady Reynolds-averaged Navier–Stokes equations using the Spalart–Allmaras turbulence model. The calculation results confirm the existence of loops of static aerodynamic hysteresis and bistable structures of the separated flow, and the results are qualitatively similar to the results observed experimentally on the wing with a finite aspect ratio.Item Metadata only Pushing Ahead - SUPRA Airplane Model for Upset Recovery(American Institute of Aeronautics and Astronautics, 2012) Abramov, Nikolay; Goman, M. (Mikhail G.); Khrabrov, A. N. (Alexander N.); Kolesnikov, E. N.; Fucke, Lars; Soemarwoto, B.; Smaili, H.One of the primary objectives of the European Union 7th Framework Program research project SUPRA – “Simulation of Upset Recovery in Aviation” – is the development and validation of the aerodynamic model of a generic large transport airplane aimed for piloted simulation in the post-stall region and upset recovery training. Modeling methods for prediction of post-stall flight dynamics, use of the wind tunnel data from different experimental facilities complemented by CFD analysis, validation criteria, nonlinear dynamics investigation and piloted simulation results are presented in this paper. The aerodynamic model was successfully validated by a number of expert pilots and found acceptable for upset recovery training.Item Metadata only Reducing flight upset risk and startle response: A study of the wake vortex alert with licensed commercial pilots(Elsevier, 2024-06-21) Borghini, Gianluca; Ronca, Vincenzo; Giorgi, Andrea; Aricò, Pietro; Di Flumeri, Gianluca; Capotorto, Rossella; Rooseleer, Frédéric; Kirwan, Barry; De Visscher, Ivan; Goman, M. (Mikhail G.); Pugh, Jonathan; Abramov, Nikolay; Granger, Géraud; Alarcon, Diana Paola Moreno; Humm, Elizabeth; Pozzi, Simone; Babiloni, FabioThe study aimed at investigating the impact of an innovative Wake Vortex Alert (WVA) avionics on pilots' operation and mental states, intending to improve aviation safety by mitigating the risks associated with wake vortex encounters (WVEs). Wake vortices, generated by jet aircraft, pose a significant hazard to trailing or crossing aircrafts. Despite existing separation rules, incidents involving WVEs continue to occur, especially affecting smaller aircrafts like business jets, resulting in aircraft upsets and occasional cabin injuries. To address these challenges, the study focused on developing and validating an alert system that can be presented to air traffic controllers, enabling them to warn flight crews. This empowers the flight crews to either avoid the wake vortex or secure the cabin to prevent injuries. The research employed a multidimensional approach including an analysis of human performance and human factors (HF) issues to determine the potential impact of the alert on pilots' roles, tasks, and mental states. It also utilizes Human Assurance Levels (HALs) to evaluate the necessary human factors support based on the safety criticality of the new system. Realistic flight simulations were conducted to collect data of pilots' behavioural, subjective and neurophysiological responses during WVEs. The data allowed for an objective evaluation of the WVA impact on pilots' operation, behaviour and mental states (mental workload, stress levels and arousal). In particular, the results highlighted the effectiveness of the alert system in facilitating pilots' preparation, awareness and crew resource management (CRM). The results also highlighted the importance of avionics able to enhance aviation safety and reducing risks associated with wake vortex encounters. In particular, we demonstrated how providing timely information and improving situational awareness, the WVA will minimize the occurrence of WVEs and contribute to safer aviation operations.Item Metadata only Synthetic Aerodynamics Modeling for Pilot Training in the Extended Flight Envelope(2013-11-21) Murthy, P V Satyanarayana; Abramov, Nikolay; Goman, M. (Mikhail G.)Flight at high angles of attack is associated with a variety of types of aircraft departure and post stall behaviour. Every aircraft will exhibit specific set of flight characteristics in extended flight envelope. This work was motivated by the need for using flight simulator in training pilots in those high angles of attack conditions to give pilots awareness about nonlinear aircraft behaviours and peculiarities of flight at stall and above stall. Flight simulators, equipped with representative aerodynamic models covering normal and extended flight envelope can be utilised for this purpose. A special approach of building a synthetic aerodynamic model over an available high angle of attack aerodynamic model is discussed in this paper. The Synthetic modelling presented in this paper assumes complementary transformation of a number of key aerodynamic characteristics of the original aerodynamic model with an objective to diversify post stall dynamics.Item Open Access Wing Rock Prediction in Free-to-Roll Motion Using CFD Simulations(Aerospace Europe Conference 2023 - 10th EUCASS - 9th CEAS, 2023-10-02) Sereez, Mohamed; Lambert, Caroline; Abramov, Nikolay; Goman, M. (Mikhail G.)The free-to-roll wing rock CFD simulation of a slender 80-degree delta wing is performed using the Dynamic Fluid-Body Interaction (DFBI) framework and the overlap/chimera mesh method. The purpose of the simulations carried out was to test the capabilities of the current CFD methods for predicting wing rock motion over a wide range of angles of attack, including strong conical vortex interactions and vortex breakdown phenomenon. The predictions of steady aerodynamic dependencies and the aerodynamic stability derivatives based on forced oscillation tests along with the time histories of the wing rock motion of an 80-degree delta wing are in good qualitative and quantitative agreement with the available wind tunnel experimental data demonstrating onset of the wing rock motion. At higher angles of attack with vortex breakdown CFD simulations demonstrated an excitation of the large amplitude regular oscillations or the low amplitude chaotic oscillations depending on the applied initial conditions.