Showing papers by "Mikhail Goman published in 2022"

Evaluating Longitudinal Unsteady Aerodynamic Effects in Stall for a T-Tail Transport Model

Abstract: Although there have been many proposed methods to model unsteady aerodynamic effects in the stall and poststall region, little work has been done to directly assess the impact of unsteady aerodynamic models on stability and control characteristics. In this paper, the state-space method for unsteady aerodynamic modeling is combined with bifurcation analysis to examine the sensitivity of stall and poststall behavior to the choice of aerodynamic modeling method: quasi-steady or unsteady. It is found that quasi-steady modeling can adequately capture the dynamics of the chosen example of a T-tailed transport aircraft with negligible wing–tail coupling. The study is then expanded to investigate a hypothetical situation with highly unsteady aerodynamic characteristics resembling a delta wing configuration—achieved by increasing the time delay constants in the unsteady model. This results in an aircraft with significantly lower flying qualities as indicated by bifurcation analysis. These findings highlight the need to implement unsteady aerodynamic modeling techniques in high-performance aircraft with significant vortex-related unsteady aerodynamics in order to sufficiently capture their stall and poststall dynamics.

Investigation of Aerodynamic Characteristics of a Generic Transport Aircraft in Ground Effect Using URANS Simulations

Abstract: 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. results based on the URANS equations are generally in good agreement with wind tunnel data in ground effect for symmetric longitudinal attitudes, and this motivates us to extend the simulation to more general aircraft attitudes. To better understand the lateral-directional dynamics during landing, this paper focuses on URANS simulations of an aircraft’s aerodynamics near the ground for its attitude with non-zero bank angles.

Evaluation of Aerodynamic Characteristics in Oscillatory Coning Using CFD Methods

Abstract: 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.