Türbülans Modeli Seçiminin Zemin Etkisindeki 3B Bir Kanatın Sayısal Modellemesine Olan Etkisi

Bu çalışma, farklı RANS türbülans modellerinin Zemin etkisinde çalışan 3B simetrik bir kare kanatın sayısal modellemesindeki etkisini incelemektedir. Katı bir Zemin yakınında hareket etme, ya da bilinen ismiyle yer etkisi, bir kanatın aerodinamik karakteristiğini öenmli oranda etkiler. Bu makalede amaç, farklı eddy viskozitesi türbülans modellerinin yer etkisi esnasındaki aerodinamik davranışı modelleme yönünden performansının araştırılmasıdır. Üç farklı türbülans modeli, realizable , SST and Spalart-Allmaras modelleri incelemeye dahil edilmiştir. Türbülans modellerinin etkinlikleri farklı hücum açıları ve kanat yükseklikleri için deneysel verilerle karşılaştırmalı olarak test edilmiştir. Sonuçlar göstermektedir ki, türbülans modellerinin yer etkisi aerodinamiği hesaplamaları konusundaki başarısı irtifa ve hücum açısı ile doğrudan ilişkilidir. Türbülans modeli seçimi kanat yere çok yakın hareket edşyorken ve hücum açısı düşük ya da negatifken önemli hale gelmektedir. Elde edilen sonuçların birbirlerinden farklılığı temel olarak kanat alt yüzeyindeki basınç dağılımından kaynaklanmaktadır. Yüksek hücum açıları ve irtifalarda farklı türbülans modelleri ile elde edilen tahminler arası fark ihmal edilebilir düzeyde kalmaktadır.

Anahtar Kelimeler:

Zemin Etkisi, Kare Kanat, Aerodinamik, HAD, Türbülans modelleri, RANS

The Influence of Turbulence Models on the Numerical Modelling of a 3D Wing in Ground Effect

This paper deals with the influence of different RANS turbulence models on the numerical modelling of a 3D rectangular symmetrical wing in ground effect. Travelling near a solid surface, so-called ground effect, considerably alters the aerodynamic characteristics of a wing. This paper aims to investigate the performance of the widely used eddy viscosity turbulence models while predicting the changing aerodynamic behavior due to the ground effect. Three different RANS turbulence models, realizable , SST and Spalart-Allmaras models are taken into consideration. The effectiveness of the turbulence models were tasted in comparison with the experimental data in different angles of attack and ground heights. Results reveals that, the effect of the turbulence models on the numerical accuracy of the ground effect aerodynamics calculations are related to the altitude and the angle of attack. The choice of the turbulence model becomes important when the wing travels in very close proximity to the ground and the angle of attack is low or negative. The discrepancy of the calculated results mainly comes from the pressure distribution variations on the lower side of the wing. For high angles of attack, or relatively larger ground heights, the difference between the predictions of the turbulence models become negligible.

Keywords:

Ground effect, Rectengular wing, Aerodynamics, CFD, Turbulence models, RANS,

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