Numerical Study of a Training Aircraft Models Flow-Around Structure

Аuthors

Arzhanov Y. I.^*, Pimenov I. A.^**, Kornev S. V.^***, Demina Z. P.^****

Russian Aircraft Corporation «MiG», 6, Leningradskoe shosse, Moscow, 125171, Russia

*e-mail: Arganoff @yandex.ru
**e-mail: Pimenov.ilya2020@yandex.ru
***e-mail: sergeikornev@mail.ru
****e-mail: Zla7321@yandex.ru

Abstract

The presented article deals with the flow-around numerical modeling of the training aircraft with two options of the horizontal tail surfaces mounting along the tail fin height:
Option 1: the tail fin is mounted in the middle of the tail fin height;
Option 2: the T-shaped tail surface.
Computation reliability is being confirmed by the experimental studies conducted in the T-102 wind tunnel.
The need to study the favorable area of the horizontal tail surface mounting along the fin height is associated with the peculiarity of its flow-around by the separated flows formed on the wing when the aircraft reaches high angles of attack. When the horizontal tail hits the vortex flows area behind the wing, the dependence of the longitudinal moment on the angle of attack becomes significantly nonlinear, which negatively affects the intuitiveness of aircraft control and leads to the need for the control system complication.
The MiG-AT aircraft was selected as the object of study. To perform numerical simulation of the flow-around a training aircraft, two geometric models with a medium and T-shaped arrangement of the tail surface on the fin were created with the CAD packages. Subsequently, a computation area was created in the ANSYS software package. An unstructured tetrahedral grid was constructed in the computational domain, thickening to the surface of the aircraft for correct viscosity modeling in the boundary layer.
The flow-around simulation of the aircraft with different options of the tail-surface installation area was performed at the angles of attack in the range of 0–25° with a 5° increment. After the computations, graphs of the dependence of the coefficients of drag, lift and longitudinal moment on the angle of attack were plotted. The results of experimental studies were plotted on the graphs as well, which confirmed good qualitative convergence of the results.
The momentum envelope origination for a model with a T-shaped tail surface can be observed on the graphs.
To analyze the causes of this phenomenon origination, sections were constructed displaying the areas of velocity distribution near the wing and horizontal tail. The flow velocity distribution patterns demonstrate that both tail options stay outside the wake area behind the wing up to the attack angle of 15°. With a further increase in the angle of attack, the aircraft configuration with the horizontal tail surface located in the middle of the fin starts entering the area of the separation wake from the wing, while the option with the T-shaped tail remains outside this area. A consequence of this difference in flow-around is the difference in the bearing properties of the tail: the value of the longitudinal dive moment for the T-shaped tail is higher than that for the tail located in the middle of the fin. With a further increase in the attack angle, the T-shaped tail begins to enter the wake zone behind the wing. A decrease in the velocity pressure on the tail leads to a sharp decrease in its bearing properties, in association with which a change in the sign of the derivative of the longitudinal moment with respect to the angle of attack occurs, and a momentum envelope is being formed. This phenomenon indicates local instability and affects negatively the aircraft controllability.

Keywords:

training aircraft, tail plane, tail fin, momentum envelope, flow-around visualization, aerodynamic wake

References

1.  Lake J. Aero L-39 Albatros Family Variant Briefing. World Air Power Journal. 2000;43:116-131.
2.  Dolzhenkov NN. Yak-130 – a new generation of combat training aircraft. Voennyi parad. 1999;33(3):60.
3.  Arsen'ev EV, Valuev YuF, Polushkin YuF. “MiG”: polet skvoz' vremya (“MiG”: flight through time). Moscow: Reklamnoe agenstvo AleksV; 2020. Vol. 2. 641 p.
4.  Akimov AN, Vorob'ev VV, Demchenko OF. et al. Osobennosti proektirovaniya legkikh boevykh i uchebno-trenirovochnykh samoletov (Combat aircraft and trainer airplane peculiarity design). Moscow: Mashinostroenie-Polet; 2005. 366 p.
5.  Gulyaev VV, Demchenko OF, Dolzhenkov NN. et al. Matematicheskoe modelirovanie pri formirovanii oblika letatel'nogo apparata (Mathematical modeling configuration of a flying vehicle). Moscow: Mashinostroenie–Polet; 2005. 496 p.
6.  Arzhanov YuI, Ashnevits AYa, Vizel' EP. Investigation aerodynamic characteristics of maneuverable aircraft layouts with two and three bearing surfaces. Tekhnika vozdushnogo flota. 2011(2):1–18.
7.  Chernov LG, Milovanov AG. Osnovy metodologii aerodinamicheskogo proektirovaniya manevrennogo mnogorezhimnogo samoleta-istrebitelya (Fundament of aerodynamic design manoeuvrable multi-mode fighter). Moscow: MAI-PRINT; 2008. 235 p.
8.  Arep'ev AN. Proektirovanie legkikh passazhirskikh samoletov samoletov (Light airplane design). Moscow: MAI; 2006. 637 p.
9.  Kornev SV, Pimenov IA. Numerical investigation of velocity field behind the wing by different vertical position horizontal tail. Trudy MAI. 2022(123). DOI: 10.34759/trd-2022-123-07
10.  Byushgens GS, Studnev RV. Aerodinamika samoleta. Dinamika prodol'nogo i bokovogo dvizheniya (Airplane aerodynamics. Dynamics of pitching and lateral motion). Moscow: Mashinostroenie; 1979. 349 p.
11.  Vozhdaev ES, Golovkin VA, Golovkin MA. et al. Metods of influencing the vortex structure of an high angles of attack. Uchenye zapiski TsAGI. 1996;27(1-2):3-19.
12.  Cunningham K, Shah GH, Frink NT. et al. Preliminary test results for stability and control characteristics of a generic T-tail transport airplane at high angle of attack. AIAA Atmospheric Flight Mechanics Conference (January 08–12, 2018; Kissimmee, Florida). DOI: 10.2514/6.2018-0529
13.  Rizzi A. Modeling and simulating aircraft stability and control - The SimSAC project. Progress in Aerospace Sciences. 2011;47(8):573-588. DOI: 10.1016/j.paerosci.2011.08.004
14.  Schlichting H, Gersten K. Grenzschicht-Theorie. Springer; 2006. 822 p.
15.  Mkhitaryan AM. Aerodinamika (Aerodynamic). 2nd ed. Moscow: Mashinostroenie; 1976. 445 p.
16.  Anisimov KS, Kazhan EV, Kursakov IA. et al. Aircraft layout design employing high-precision methods of computational aerodynamics and optimization. Aerospace MAI Journal. 2019;26(2):7-19.
17.  Voronich IV, Kolchev SA, Panchuk DV. et al. On aerodynamics specifics of a small-sized aircraft of normal configuration. Trudy MAI. 2019(109). DOI: 10.34759/trd-2019-109-8
18.  Shevchenko AV, Muravitskaia LA. Computational and experimental studies of aerodynamic characteristics of unmanned aerial vehicles at subsonic speeds. Trudy MAI. 2024(138). URL: https://trudymai.ru/eng/published.php?ID=182661
19.  Nicolosi F., Ciliberti D., Vecchia P.D. et al. Aerodynamic design guidelines of an aircraft dorsal fin. 34th AIAA Applied Aerodynamics Conference (June 13-17, 2016; Washington, D.C.). DOI: 10.2514/6.2016-4330
20.  Kirillin AA, Fedotov EN, Kharlamov SN. K-ε model' turbulentnosti i ee primenenie. Trudy XXI Mezhdunarodnogo simpoziuma im. ak. M.A. Usova (April 3-7, 2017; Tomsk). Tomsk: TPU; 2017. Vol.2. p. 714-716.