In this study, the optimization of a low-speed wing with functional constraints is discussed. The aerodynamic analysis tool developed by the coupling of the numerical nonlinear lifting-line method to Xfoil is used to obtain lift and drag coefficients of the baseline wing. The outcomes are compared with the results of the solver based on the nonlinear lifting-line theory implemented into XLFR5 and the transition shear stress transport model implemented into ANSYS-Fluent. The agreement between the results at the low and moderate angle of attack values is observed. The sequential quadratic programming algorithm of the MATLAB optimization toolbox is used for the solution of the constrained optimization problems. Three different optimization problems are solved. In the first problem, the maximization of C 3/2 L /C D is the objective function, while level flight condition at maximum C 3/2 L /C D is defined as a constraint. The functional constraints related to the wing weight, the wing planform area, and the root bending moment are added to the first optimization problem, and the second optimization problem is constructed. The third optimization problem is obtained by adding the level flight condition and the available power constraints at the maximum speed and the level flight condition at the minimum speed of the baseline unmanned air vehicle to the second problem. It is demonstrated that defining the root bending moment, the wing area, and the available power constraints in the aerodynamic optimization problems leads to more realistic wing planform and airfoil shapes.
In this numerical study, the effects of the initial y plus, which is a dimensionless wall distance, on the results of aerodynamic coefficients of designed a wing using NACA 4412 airfoil are investigated. For this purpose, the wing is designed and external flow analysis is carried out according to constant altitude. ANSYS Fluent, which is a Computational Fluid Dynamics (i.e. CFD) program and solves the problems according to the Finite Volume Method (i.e. FVM), is used for external flow analysis. Pressure-based method is used for numerical studies. Thus, the differences of coefficients on the wall, which are the results of the change in the initial y plus, are calculated ideally. Because of one of the best methods to solve the problems on transition zone, γ-Reθ SST turbulence model is used for this study. Using this model for each analysis, first element heights (i.e. the distance to the nearest wall) are calculated according to 9 different y plus (i.e. 1, 5, 10, 30, 45, 60, 75, 90, 105). According to the first element heights, the inflation layers are created on the wing and the 3D control volumes are formed along the boundary region. To be more comprehensible, orthogonal quality-skewness values, expressing the quality of control volumes, are presented for each boundary. The changes in lift coefficients and drag coefficients on the same wing according to these 9 different y plus are presented numerically. In addition, obtained results are evaluated and as described in the literature, it is observed that to calculate the aerodynamic forces with the γ-Reθ SST turbulence model is directly proportional to the initial y plus. As a consequence, this paper demonstrates that there are obvious differences detection of separation and determination of reattach region of flow occurring on the wing according to the initial y plus.
In this article, combined active flow control system and flight control system design for morphing unmanned aerial vehicles is applied for the first time for autonomous flight performance maximization. For this purpose, longitudinal and lateral dynamics modeling of morphing unmanned aerial vehicle having active flow control manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory is considered in order to obtain simulation environments. Our produced morphing unmanned aerial vehicle is called as ZANKA-II, which has a mass of 6.5 kg, range of 30 km, endurance of 0.5 h, and ceiling altitude of 6000 m. von Karman turbulence modeling is used in order to model atmospheric turbulence during flight in both longitudinal and lateral simulation environments. A stochastic optimization method called as simultaneous perturbation stochastic approximation is also applied for the first time in order to obtain optimum dimensions of morphing parameters (i.e. extension ratios of wingspan and tail span), optimum positions of blowers, and optimum magnitudes of longitudinal and lateral controllers' gains (i.e. P, I, and D gains) while minimizing cost index capturing terms for both longitudinal and lateral autonomous flight performances and there exist lower and upper constraints on all optimization variables in the literature.
Bu çalışmada, NACA 0012 simetrik kanat profiline sahip, ticari amaçlı bir yolcu uçağının yatay dengeleyicisi ve bu yatay dengeleyicinin ucuna yerleştirilen iki farklı kıvrık kanat ucu yapısının üzerinde farklı hücum açılarında oluşan aerodinamik kuvvetler incelenmiştir. Yatay dengeleyici, SolidWorks tasarım programında 200 noktadan oluşan kanat profili eğrisi ve belirlenen V açısı, ok açısı ve sivrilme oranları kullanılarak tasarlanmıştır. Bu tasarım C 1 olarak tanımlanmıştır. C 1 tasarımının uç kısmına, aynı ok açısına, bükme açısına, sivrilme oranına, açıklığa, yüksekliğe sahip; fakat uç kısmındaki kanat profili kalınlığı farklı olan iki kıvrık kanat ucu yapısı tasarlanarak toplamda üç kanat tasarımı elde edilmiştir. Bu tasarımlar sırası ile C 2 ve C 3 olarak adlandırılmıştır. Üç farklı tasarımın aerodinamik analizi, bir hesaplamalı akışkanlar dinamiği programı olan Fluent kullanılarak yapılmıştır. On üç farklı hücum açısında gerçekleştirilen analizler sonucunda elde edilen sonuçlara göre tasarımların üzerindeki sürükleme (C D) ve taşıma (C L) katsayılarındaki değişimler gözlemlenmiştir. Elde edilen sonuçlara göre, C 2 tasarımı için analizlerin yapıldığı bütün hücum açılarında daha yüksek taşıma kuvvetinin sürükleme kuvvetine oranına (C L /C D) sahip olduğu görülmüştür. C 3 tasarımı için ise-1 derece hücum açısındaki sonuç haricinde aynı sonuç elde edilmiştir.
Purpose The purpose of this study is to increase maximum lift/drag ratio (Emax) of tactical unmanned aerial vehicles (TUAVs) via applying novel small aerodynamic modifications. Design methodology/approach A TUAV is manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory. It has both passive and active morphing capabilities. Its nosecone and tailcone shapes are redesigned to improve Emax. Moreover, active flow control is also built on its wing for improving Emax. Findings Using these novel small aerodynamic modifications, considerable improvement on Emax is obtained. Research limitations/implications Permission of Directorate General of Civil Aviation in Turkey is required for testing TUAVs in real-time applications. Practical implications Small aerodynamic modifications such as nosecone-tailcone shape modifications and building active flow control on wing are very beneficial for improving Emax of TUAVs. Social implications Small aerodynamic modifications satisfy confidence, high performance and easy utility demands of TUAV users. Originality/value The study will enable the creation of novel approaches to improve Emax value and therefore aerodynamic performance of TUAVs.
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