Control of flow structure on VFE-2 delta wing with passive bleeding using CFD

Download

index.pdf

Date

2018

Author

Sayılır, Serdar Emin

Metadata

Show full item record

Item Usage Stats

288
views

273
downloads

The utilization of slender delta wings on military platforms like fighter jets and missiles has been a great topic of aerodynamics research for many decades from both experimental and numerical point of view as a result of their superior contributions to the flight performance. Second Vortex Flow Experiment (VFE-2) was carried out by NATO Research and Technology Organization between 2003 and 2008 to judge the realistic capability of the CFD codes which had been developed for simulating the leading edge vortices and their breakdowns occurring on this type of wings. In the present study, the turbulent vortical flow and its breakdown in incompressible conditions over a generic VFE-2 wing were modeled using commercial code, ANSYS Fluent. First, the grid independence study was conducted for the sharp edged 65° swept VFE-2 wing to ensure the results of the simulations do not vary with mesh density. Then, different RANS based turbulence models including Spalart-Allmaras (S-A) and SST k-ω with curvature corrections were used for validation purposes where the results of the current study were compared with both Detached Eddy Simulation (DES) results and the experimental data available in the literature. The results indicated that SST k-ω model with curvature correction was quite successful in simulating the vortical flow particularly in terms of the secondary separations and predicting the vortex breakdown location. Once a complete confidence of the grid and the turbulence model was ensured, flow control using passive bleeding was tested to check the effectiveness of bleeding on manipulating the flow field and delaying the location of vortex breakdown. The bleeding method bases on the idea of letting the air stream from the pressure side of the wing to the suction side through the holes on the wing body and injecting it into the vortical flow field to strengthen the vortex structure and delay its breakdown. For delta wings, only a limited number of applications of this passive approach yet have been implemented up until now. In the present study, the control technique was applied in three sets of investigation including variation in sizes, inclination angles and shapes of bleed holes; where in each set one parameter was altered with keeping the others constant. For each investigation set, a delay of breakdown to about 10% of the chord wise location compared to the no-control case as well as a slight improvement in the lift force and coefficient was achieved. Combining the best case parameters from each set, however, resulted a less retardation compared to the each parameter’s individual control performance.

Subject Keywords

Airplanes, Leading edges (Aerodynamics)., Computational fluid dynamics., Flow visualization., Vortex-motion.

URI

http://etd.lib.metu.edu.tr/upload/12621811/index.pdf
https://hdl.handle.net/11511/27021

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Control of flow structure on 70° swept delta wing with along-the-core blowing using numerical modeling Küçükyılmaz, İbrahim Can; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2016) In recent years, interest has increased in Unmanned Combat Air Vehicles (UCAVs) and Unmanned Air Vehicles (UAVs), which can be represented by simplified planforms including delta wings. Delta wings experience the formation of two counter-rotating vortices on the leeward side of the planform due to the shear layer separated from the windward side. At sufficiently high angle of attack, these vortices undergo sudden expansion, called vortex breakdown/burst, which is quite detrimental considering the aerodynami...
Control of flow structure on 45 degree swept delta wing using passive bleeding Karagöz, Burcu; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2017) In recent decades, researchers aim to understand and control the physical phenomenon behind the complex flow structure of low swept delta wings arising with their widespread use in Unmanned Air Vehicles (UAV), Unmanned Combat Air Vehicles (UCAV) and Micro Air Vehicles (MAV). In order to extend the working capabilities of these vehicles with having stable flight performance, detailed studies on understanding and controlling the flow structures over low swept delta wings are required. The aim of the present s...
Effect of thickness-to-chord ratio on aerodynamics of non-slender delta wing Sharifi Ghazijahani, Mohammad; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2018) Flow characterization over delta wings have gained attention in recent decades due to their prevailing usage in designs of unmanned air vehicles (UAVs). In literature,only a few studies have reported wing thickness effect on both the aerodynamic performance and detailed flow structure over delta wings. In the present investigation, the effect of thickness-to-chord (t/C) ratio on aerodynamics of a non-slender delta wing with 45 degree sweep angle is characterized in a low-speed wind tunnel using laser illumi...
Control of flow structure on low swept delta wing with staedy leading edge blowing Zharfa, Mohammadreza; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2014) Unmanned Combat Air Vehicles (UCAVs), Unmanned Air Vehicles (UAVs) and Micro Air Vehicles are becoming extremely popular due to introducing many advantages to defense industry and aeronautical field. In line with this, the aerodynamics of these vehicles, which can be represented by simplified planforms, including delta wings, have been of considerable interest in recent years. This interest has stimulated investigation of the flow structure, as well as its control, on delta wings having low and moderate val...
Development and implementation of novel flow control techniques for nonslender delta wings Çelik, Alper; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2017) Understanding and controlling the physical phenomenon behind the aerodynamics of low to moderate swept delta wings has been a challenge for researchers during the last few decades, which is stimulated by their widespread use in unmanned combat air vehicles (UCAVs) and micro air vehicles (MAVs). Although delta wings are capable of generating high lift and stable flight performance at high angle of attack, the problems related to lack of conventional flow control surfaces compel the researchers to explore new...

Citation Formats

S. E. Sayılır, “Control of flow structure on VFE-2 delta wing with passive bleeding using CFD,” M.S. - Master of Science, Middle East Technical University, 2018.