Numerical And Experimental Investigation Of 2D Membrane Airfoil Performance

The characteristic feature of a mammalian flight is the use of thin compliant wings as the lifting surface. This unique feature of flexible membrane wings found in flying mammals such as bats and flying squirrel was studied in order to explore its possibility as flexible membrane wings in aerodynamics performance study. The unsteady aspects of the fluid-structure interaction of membrane wings are very complicated and therefore did not receive much attention compared to the rigid wing. Motivated by this, a membrane airfoil consisting of latex sheet mounted on a NACA 643-218 airfoil frame was developed to study effect of membrane flexibility on laminar separation bubble (LSB), effects of membrane thickness, Reynolds number (Re), and membrane rigidity on the aerodynamic performance (lift and drag), meant for low Re applications. Unsteady, two dimensional (2D) simulations were also carried out on rigid and membrane airfoils with the air flow modeled as Laminar and the turbulent cases being modeled using Spalart-Allmaras viscous model. FLUENT 6.3 was employed to study the fluid flow behavior, whereas ABAQUS 6.8-1 was utilized as structural solver, both of which were coupled in real time using the MpCCI 3.1 software. It has been established that, the LSB is greatly influenced by the membrane flexibility, and the membrane airfoil has superior flow separation characteristics over rigid one

Modelling of Industrial Hybrid Bonding Processes considering Fluid-Structure-Interaction

The subject of the work presented is focused on self-pierce-riveting and clinching in combination with adhesive bonding. In the industrial process chain the rivets and clinch-points are set before the adhesive is cured. A FEA reference model is developed for the elementary mechanical joining processes. The model is then expanded to consider the displacement of the liquid adhesive, including associated internal pressures. Coupled fluid-structure simulations, which include the interaction of the solid matter influenced in the mechanical joining process and the fluid adhesive, are presented. In a last step a surrogate model for the multi-point hybrid joint is developed and applied to industry-relevant structures

Software coupling and Orchestration Tool to the Modeling of Multi-physic Problem

International audienceWe present in this paper Scot, which is a modular software solution for weakly coupling models, methods and orchestration of the simulation. The goal behind Scot is to make easier the phase of modeling and optimize the phase of simulation by tuning the solvers simulation parameters. Specifications and composition of Scot will be described. Scot has been successfully validated by two different applications, the PEEC-MoM coupling to the modeling of an electromagnetic device and the magneto-mechanic coupling to the modeling of deformable nano-switch contact NEMS

Developing Optimized Trajectories Derived from Mission and Thermo-Structural Constraints

In conjunction with NASA and the Department of Defense, the Johns Hopkins University Applied Physics Laboratory (JHU/APL) has been investigating analytical techniques to address many of the fundamental issues associated with solar exploration spacecraft and high-speed atmospheric vehicle systems. These issues include: thermo-structural response including the effects of thermal management via the use of surface optical properties for high-temperature composite structures; aerodynamics with the effects of non-equilibrium chemistry and gas radiation; and aero-thermodynamics with the effects of material ablation for a wide range of thermal protection system (TPS) materials. The need exists to integrate these discrete tools into a common framework that enables the investigation of interdisciplinary interactions (including analysis tool, applied load, and environment uncertainties) to provide high fidelity solutions. In addition to developing robust tools for the coupling of aerodynamically induced thermal and mechanical loads, JHU/APL has been studying the optimal design of high-speed vehicles as a function of their trajectory. Under traditional design methodology the optimization of system level mission parameters such as range and time of flight is performed independently of the optimization for thermal and mechanical constraints such as stress and temperature. A truly optimal trajectory should optimize over the entire range of mission and thermo-mechanical constraints. Under this research, a framework for the robust analysis of high-speed spacecraft and atmospheric vehicle systems has been developed. It has been built around a generic, loosely coupled framework such that a variety of readily available analysis tools can be used. The methodology immediately addresses many of the current analysis inadequacies and allows for future extension in order to handle more complex problems

Fluid-Structure Interaction of NREL 5-MW Wind Turbine

Wind energy is considered one of the major sources of renewable energy. Nowadays, wind turbine blades could exceed 100 m to maximize the generated power and minimize produced energy cost. Due to the enormous size of the wind turbines, the blades are subjected to failure by aerodynamics loads or instability issues. Also, the gravitational and centrifugal loads affect the wind turbine design because of the huge mass of the blades. Accordingly, wind turbine simulation became efficient in blade design to reduce the cost of its manufacturing. The fluid-structure interaction (FSI) is considered an effective way to study the turbine\u27s behavior when the air and the blade are simulated as one system. In the present study, NREL 5 MW wind turbine with a blade length of 61.5m long is selected as a reference turbine to apply the FSI. The FSI is performed using three commercial software. ANSYS Fluent is used for the Computational Fluid Dynamics (CFD) model. The Finite Element (FE) model is simulated by Abaqus. In order to link both models together and transfer the data between them, MPCCI software is used. The blade is subjected to flap-wise deflection, edge-wise deflection, and torsion. So, a 2-way coupling simulation is implemented to optimize the blade deformation to protect it from hitting the tower, mitigate the effect of cyclic loading, and prevent the blade stall. This study introduced two passive optimization methods: material Bend Twist Coupling (BTC) and blade root fixation. One of the achievements of this study is that it is considered the first FSI research implemented at the AUC. Also, running the FSI model with three different codes and linking between them was another challenge. Moreover, it is concluded from this research that the 2-way coupling gives more accurate results than the 1-way coupling, although it is complicated. Although the centrifugal force reduces the flap-wise deflection, it significantly impacts the blade twist angle. The used material BTC optimization method improved the blade torsion stiffness while the root fixation improved the longitudinal stiffness. The improvement in the blade protects it from fatigue loading and stall by reducing the peak-to-peak amplitude and twisting the blade to feather

Uçak-uzay Yapilarinin Statik Aeroelastik Kriter Ile Çok Disiplinli Tasarim Optimizasyonu

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2008Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2008Bu tez çalışmasında aeroelastik optimizasyon, AGARD 445.6 elastik kanat konfigürasyonundan yola çıkılarak basit bir kanat için en yüksek taşıma/sürükleme oranı ve en düşük kütle amaç fonksiyonlarına ulaşmak için yapılmıştır. Tasarım kısıtı olarak bir statik aerolastik kriter olan en yüksek uç yer değiştirmesi verilmiştir. Kanadın çeyrek veterdeki ok açısı ve sivrilme oranı tasarım parametreleri olarak atanmıştır. Optimizasyon algoritması olarak bir genetik algoritma olan NSGA—II algoritması kullanılmıştır. Optimizasyon çalışmasında çok amaçlı tasarım ortamı (mode)FRONTIER 4.0 optimizasyon yazılımı kullanılmıştır. Bu çalışmayı yapmak için çeşitli betikler yazılmıştır: ABAQUS 6.7-1 sonlu eleman çözücüsü betiği yapısal modeli hazırlamak için, FLUENT 6.3.26 ve GAMBIT 2.2.30 betikleri akışkan modelini hazırlamak için ve çözüm ağı tabanlı paralel kod eşleme arayüzü MpCCI 3.0.6 ise gevşek bağlaşımlı aeroelastik analizleri yürütmek için kullanılmıştır. Aeroelastik analizler bir sıralı “staggered” algoritma kullanılarak çözülmüştür. Aerodinamik yüzey yükleri düğüm bazlı kuvvetlere çevrilerek yapısal çözücüye aktarılmakta, bu yükler altında yapılan statik analiz sonucunda oluşan yer değiştirmeler ise akışkan koduna çözüm ağı hareketi olarak gönderilmektedir. Yapısal, akışkan ve aeroelastik analizler sonunda alınan sonuçlar AGARD 445.6 kanadı üstüne yapılmış önceki sayısal ve rüzgar tüneli verileri ile karşılaştırılmıştır. Karşılaştırmadan sonra geçerliliği onaylanan kanat kullanılarak aeroelastik optimizasyon çalışması yapılmıştır. Aeroelastik optimizasyon sonunda en uygun çözümü seçebilmek için pareto kümesi oluşturulmuştur. Tasarım değişkenlerinin amaç fonksiyonları üzerindeki etkileri ve aralarında ilişki modeFRONTIER 4.0 yazılımının sonuç değerlendirme araçları kullanılarak yapılmıştır.In this thesis aeroelastic optimization is performed on a basic experimental wing model based on AGARD 445.6 elastic wing configuration to obtain the objectives maximum lift/drag ratio and minimum weight of the wing. A static aeroelastic criteria is given as a design constraint to satisfy the maximum tip deflection. Sweep angle at the quarter chord and the taper ratio of the wing are used as design parameters. Moreover, a genetic algorithm NSGA-II is used to control the optimization process. The optimization study is done by using the Multi-Objective Design Environment (mode)FRONTIER 4.0 optimization software with the written: ABAQUS 6.7-1 finite element solver script to prepare the CSD model, FLUENT 6.3.26 and GAMBIT 2.2.30 scripts to prepare the CFD model and Mesh based Parallel Code Coupling Interface-MpCCI 3.0.6 script to perform loosely coupled aeroelastic analysis. Aeroelastic analysis is done by using a staggered algorithm. Aerodynamic surface pressures converted to nodal forces and transferred to the CSD code, then under these forces static analysis is performed and nodal displacements are transfered to CFD code as mesh movements. The results from the structural, fluid and aeroelastic fields are used to compare the results with the numerical and the wind tunnel data of the AGARD 445.6 wing. Once the wing is validated the aeroelastic optimization study is performed. The pareto set for the optimum designs are obtained at the end of the aeroelastic optimization study to choose the best design configuration. The effect of the design variables on objective functions and their relationship are examined.Yüksek LisansM.Sc

multiRegionFoam -- A Unified Multiphysics Framework for Multi-Region Coupled Continuum-Physical Problems

This paper presents a unified framework, called multiRegionFoam, for solving multiphysics problems of the multi-region coupling type within OpenFOAM (FOAM-extend). This framework is intended to supersede the existing solver with the same name. The design of the new framework is modular, allowing users to assemble a multiphysics problem region-by-region and coupling conditions interface-by-interface. The present approach allows users to choose between deploying either monolithic or partitioned interface coupling for each individual transport equation. The formulation of boundary conditions is generalised in the sense that their implementation is based on the mathematical jump/transmission conditions in the most general form for tensors of any rank. The present contribution focuses on the underlying mathematical model for these types of multiphysics problems, as well as on the software design and resulting code structure that enable a flexible and modular approach. Finally, deployment for different multi-region coupling cases is demonstrated, including conjugate heat, multiphase flows and fuel-cells

Validation of CAE based Methodology to Predict Sloshing Noise in Automotive Fuel Tank

Due to advancement in technology major noise sources in an automotive car such as engine, transmission, aerodynamic noise, tyre road noise have significantly reduced. Thus sources of noise such as sloshing noise in a fuel tank which previously did not contribute much in the overall SPL have become more significant now. Also in high end luxury cars and hybrid cars sloshing noise is considered as an irritant. All major international OEMs and their suppliers try to reduce sloshing noise by various design modifications in the fueltank