THE EFFECT OF WAVE PARAMETERS ON AERODYNAMIC COEFFICIENTS DURING WING-IN-GROUND EFFECT FLIGHT

Abstract

In this study, the ground effect, which affects the aerodynamic performance of aircraft flying near wavy ground was investigated with time-dependent 2D Unsteady RANS-based Computational Fluid Dynamics (CFD) analyses. Analyses were conducted using a NACA 4412 airfoil under various wave amplitudes, wavelengths, and angles of attack. In the analyses, the airfoil was held stationary, and a sinusoidal moving ground model was applied underneath to simulate the periodic wave effect. The variation of lift, drag, and moment coefficient (CL, CD, Cm) values according to different wave positions was determined. It was determined that the highest CL occurred when approaching the wave crest and the lowest when approaching the trough. The effects of wave parameters, angles of attack, and proximity to the ground on the airfoil were analyzed. Results reveal that lift coefficient (CL) varies by 26.04 % over a wave period (from 0.962 to 1.250) for the most dynamic case (AOA=8°, h/c=0.4, λ/c=1, α/c=0.2). Maximum lift occurs at wave crests (CL=1.250), representing a 14.2% increase relative to time-averaged values, while minimum lift at wave troughs shows a 13% decrease. Ground clearance reduction from h/c=0.8 to h/c=0.4 amplifies fluctuations by 37%, while wavelength increase from λ/c=1 to λ/c=3 reduces variations by 58%.

Keywords

• Wavy ground
• Lift
• Drag
• Wavelength
• Wave Amplitude
• Unsteady RANS

YER ETKİSİ ALTINDA UÇUŞTA DALGA PARAMETRELERİNİN AERODİNAMİK KATSAYILAR ÜZERİNDE ETKİSİ

Abstract

Bu çalışmada, dalgalı zemine yakın uçan uçakların aerodinamik performansını etkileyen zemin etkisi, zamana bağlı 2D Kararsız RANS tabanlı Hesaplamalı Akışkanlar Dinamiği (CFD) analizleri ile incelenmiştir. Analizler, çeşitli dalga genlikleri, dalga boyları ve hücum açıları altında NACA 4412 kanat profili kullanılarak gerçekleştirilmiştir. Analizlerde, kanat profili sabit tutulmuş ve periyodik dalga etkisini simüle etmek için altına sinüzoidal hareketli zemin modeli uygulanmıştır. Farklı dalga konumlarına göre kaldırma, sürtünme ve moment katsayısı (CL, CD, Cm) değerlerinin değişimi belirlenmiştir. En yüksek CL 'nin dalga tepesine yaklaşırken, en düşük CL 'nin ise dalga çukuruna yaklaşırken meydana geldiği belirlenmiştir. Dalga parametrelerinin, hücum açılarının ve zemine yakınlığın kanat profili üzerindeki etkileri analiz edilmiştir. Sonuçlar, en dinamik durumda (AOA=8°, h/c=0,4, λ/c=1, α/c=0,2) kaldırma katsayısının (CL) dalga periyodu boyunca %26,04 oranında değiştiğini (0,962'den 1,250'ye) ortaya koymaktadır. En yüksek kaldırma kuvveti dalga tepelerinde (CL=1,250) meydana gelir ve bu da zaman ortalamalı değerlere göre %14,2'lik bir artışı temsil ederken, dalga çukurlarında minimum kaldırma kuvveti %13'lük bir azalma göstermektedir. Yerden yüksekliğin h/c=0,8'den h/c=0,4'e düşmesi dalgalanmaları %37 oranında artırırken, dalga boyunun λ/c=1'den λ/c=3'e artması varyasyonları %58 oranında azaltmaktadır.

Keywords

• Dalgalı zemin
• Kaldırma kuvveti
• Sürükleme kuvveti
• Dalga boyu
• Dalga Genliği
• Kararsız RANS

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