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  • 1.
    López Pereira, Ramón
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems.
    Validation of software for the calculation of aerodynamic coefficients: with a focus on the software package Tornado2010Independent thesis Basic level (degree of Bachelor), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Several programs exist today for calculating aerodynamic coefficients that with some simplifications provide fast approximations of the values for a real aircraft.

    Four different programs were analyzed for this report: Tornado, AVL, PANAIR and a handbook-type preliminary method. In addition, ANSYS CFX was used for airfoil validation. For calculation of the zero lift drag, an approximation was computed in order to calculate the remaining values that were not calculated by the software: drag contribution for fuselages, nacelles and some horizontal stabilizers and fins.

    Different types of aircraft were selected for trial: two commercial aircraft (Boeing 747-100 and 777-300), a TF-8A research airplane (with area rule application: some additions were made to the fuselage to prevent large variations in the cross-section when the contribution of the wing is  added), a Lockheed Constellation C-69 u sed as a military cargo airplane, a Boeing Stratocruiser used by the USAF with two configurations (basic and bomber), and an Aero Commander 680 Super, similar to a Cessna 162. Two airfoils (NACA2412, 0012) were also analyzed, to investigate the limitations of software designed for three-dimensional calculations.

    The accuracy of the results showed that the validity of the software depends on the planform of the aircraft, as well as the simulation parameters Mach number and Reynolds number. The shape of the wing caused some of the methods to have serious difficulties in converging to valid results, or increased the simulation time beyond acceptable limits.

  • 2.
    Lopez Pereira, Ramon
    Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Validation of software for the calculation ofaerodynamic coefficients: with a focus on the software package Tornado2010Independent thesis Basic level (degree of Bachelor), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Several programs exist today for calculating aerodynamic coefficients that with some simplificationsprovide fast approximations of the values for a real aircraft.Four different programs were analyzed for this report: Tornado, AVL, PANAIR and a handbook-typepreliminary method. In addition, ANSYS CFX was used for airfoil validation. For calculation of the zerolift drag, an approximation was computed in order to calculate the remaining values that were notcalculated by the software: drag contribution for fuselages, nacelles and some horizontal stabilizersand fins.Different types of aircraft were selected for trial: two commercial aircraft (Boeing 747-100 and 777-300), a TF-8A research airplane (with area rule application: some additions were made to the fuselageto prevent large variations in the cross-section when the contribution of the wing is added), a LockheedConstellation C-69 used as a military cargo airplane, a Boeing Stratocruiser used by the USAF withtwo configurations (basic and bomber), and an Aero Commander 680 Super, similar to a Cessna 162.Two airfoils (NACA2412, 0012) were also analyzed, to investigate the limitations of software designedfor three-dimensional calculations.The accuracy of the results showed that the validity of the software depends on the planform of theaircraft, as well as the simulation parameters Mach number and Reynolds number. The shape of thewing caused some of the methods to have serious difficulties in converging to valid results, orincreased the simulation time beyond acceptable limits.

  • 3.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Parametric Airfoil Catalog, Part II: Göttingen 673 to YS930: An Aerodynamic and Geometric Comparison Between Parametrized and Point Cloud Airfoils2013Book (Other academic)
    Abstract [en]

    A fundamental part of aircraft design involves wing airfoiloptimization, establishing an outer shape of the wing which has good aerodynamic performance for the design mission, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the load of the weight of the aircraft. The underlying idea with this parametrization is to couple an appropriate number of parameters, balancing the need of geometric accuracy with the necessity of few airfoil parameters in order to facilitate en expedient optimisation, with the intrinsic value of having parameters that makes sense for a human; such as thickness, camber and trailing edge thickness. Several approaches to parametrization of wing proles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parametrization will most certainly be not well behaved, since no smoothing function is included and must therefore be employed. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parametrization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones. Airfoils can also be represented by mathematical functions. Among the most common representatives of thiscategory are indeed the NACA 4-, 5- and 6-digits formulations. Compared to point clouds, they could be said to represent the opposite case: they are very well behaving parametrizations, but they cannot cover avery large design space, since they only provide four to six parameters respectively to be tuned. The NACA 4digit series is particularly interesting as the parametersare a part of the name of the airfoil. In the case of the 5- and 6 digit series, the name is instead constructed from the airfoils aerodynamic characteristic and geometry. Another known set of theoretically defined airfoils are the Joukowski profiles [4]. Using the conformal mapping method, airfoils with a round nose and sharp trailing edge can be represented. Sadly the method is not to recommend for trying to match known airfoils and the design space it describes is quite confined to airfoils with often poor performances.

  • 4.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Parametric Airfoil Catalog Part I, Archer A18 to Göttingen 655: An Aerodynamic and Geometric Comparison Between Parametrized and Point Cloud Airfoils2013 (ed. 1)Book (Other academic)
    Abstract [en]

    A fundamental part of aircraft design involves wing airfoiloptimization, establishing an outer shape of the wing which has good aerodynamic performance for the design mission, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the load of the weight of the aircraft. The underlying idea with this parametrization is to couple an appropriate number of parameters, balancing the need of geometric accuracy with the necessity of few airfoil parameters in order to facilitate en expedient optimisation, with the intrinsic value of having parameters that makes sense for a human; such as thickness, camber and trailing edge thickness. Several approaches to parametrization of wing proles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parametrization will most certainly be not well behaved, since no smoothing function is included and must therefore be employed. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parametrization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones. Airfoils can also be represented by mathematical functions. Among the most common representatives of thiscategory are indeed the NACA 4-, 5- and 6-digits formulations. Compared to point clouds, they could be said to represent the opposite case: they are very well behaving parametrizations, but they cannot cover avery large design space, since they only provide four to six parameters respectively to be tuned. The NACA 4digit series is particularly interesting as the parametersare a part of the name of the airfoil. In the case of the 5- and 6 digit series, the name is instead constructed from the airfoils aerodynamic characteristic and geometry. Another known set of theoretically defined airfoils are the Joukowski profiles [4]. Using the conformal mapping method, airfoils with a round nose and sharp trailing edge can be represented. Sadly the method is not to recommend for trying to match known airfoils and the design space it describes is quite confined to airfoils with often poor performances.

  • 5.
    Melin, Tomas
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Amadori, Kristian
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Parametric wing profile description for conceptual design2011Conference paper (Refereed)
    Abstract [en]

    A fundamental part of aircraft design involves the wing airfoil optimization, establishing an outer shape of the wing which has good aerodynamic performance, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the weight of the aircraft. As for all optimization tasks, the complexity of the problem is directly coupled to the parameterization of the geometry. Of highest relevance are the number of parameters and the number of additional constraints that are required to ensure valid modeling.This paper proposes a parameterization method for two dimensional airfoils, aimed at providing a wide design space, while at the same time keeping the number of parameters low. With 15 parameters defining the wing profile, many of the existing airfoils can be modeled with close tolerance.

  • 6.
    Melin, Tomas
    et al.
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Amadori, Kristian
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Parametric wing profile description for conceptual design2011In: CEAS 2011 Proceedings, 2011Conference paper (Other academic)
    Abstract [en]

    A fundamental part of aircraft design involves the wing airfoil optimization, establishing an outer shape of the wing which has good aerodynamic performance, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the weight of the aircraft. As for all optimization tasks, the complexity of the problem is directly coupled to the parameterization of the geometry. Of highest relevance are the number of parameters and the number of additional constraints that are required to ensure valid modeling.This paper proposes a parameterization method for two dimensional airfoils, aimed at providing a wide design space, while at the same time keeping the number of parameters low. With 15 parameters defining the wing profile, many of the existing airfoils can be modeled with close tolerance.Several approaches to parameterization of wing profiles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries [1]. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parameterization will most certainly be not well behaved, since no smoothing function is included and must therefore be added. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parameterization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones.

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