The Experts below are selected from a list of 1113 Experts worldwide ranked by ideXlab platform

žižkovský Nikola - One of the best experts on this subject based on the ideXlab platform.

  • wing and propeller aerodynamic interaction through nonlinear lifting line theory and blade element momentum theory
    MATEC Web of Conferences, 2018
    Co-Authors: Hospodař Pavel, žižkovský Nikola
    Abstract:

    In this paper a computational methodology of aerodynamic interaction between propeller and wing is described. Presented work is focused on development of quick and accurate tool. Lifting line theory (LLT) with nonlinear Airfoil Characteristic is used to solve a finite span wing aerodynamic to predict downwash and lift distribution respectively. Blade element momentum theory (BEM) is used as a computational tool for estimating total thrust, torque, axial and tangential velocity distributions. Model of slipstream development is considered. Influence of propeller model to wing is simulated as contribution of higher dynamic pressure and change of angle of attack behind the propeller.

Hospodař Pavel - One of the best experts on this subject based on the ideXlab platform.

  • wing and propeller aerodynamic interaction through nonlinear lifting line theory and blade element momentum theory
    MATEC Web of Conferences, 2018
    Co-Authors: Hospodař Pavel, žižkovský Nikola
    Abstract:

    In this paper a computational methodology of aerodynamic interaction between propeller and wing is described. Presented work is focused on development of quick and accurate tool. Lifting line theory (LLT) with nonlinear Airfoil Characteristic is used to solve a finite span wing aerodynamic to predict downwash and lift distribution respectively. Blade element momentum theory (BEM) is used as a computational tool for estimating total thrust, torque, axial and tangential velocity distributions. Model of slipstream development is considered. Influence of propeller model to wing is simulated as contribution of higher dynamic pressure and change of angle of attack behind the propeller.

Andreas Mehrle - One of the best experts on this subject based on the ideXlab platform.

  • extension of multhopp s quadrature method to cyclic periodic lifting systems
    Acta Mechanica, 2009
    Co-Authors: Andreas Mehrle
    Abstract:

    In this contribution Multhopp’s quadrature method for the calculation of the circulation distribution in the framework of lifting line theory is extended to cyclic periodic lifting systems. Further a viscous correction term allows to account for finite Airfoil performance. It is shown that the method is capable of predicting an optimal radial circulation distribution for wings operating in swirling flow situations if coupled with an optimization procedure. An example is given where the thrust maximizing Airfoil circulation is calculated for a given vortex structure and Airfoil Characteristic. With the help of some simple performance considerations the method is able to translate the obtained circulation distribution into the actual geometry of the wing assembly.

M C Claessens - One of the best experts on this subject based on the ideXlab platform.

  • the design and testing of Airfoils for application in small vertical axis wind turbines
    2006
    Co-Authors: M C Claessens
    Abstract:

    In recent years more focus is put on the applications of wind turbines in the urban environment. One of the ways to do this is using a turbine with a vertical axis (a VAWT). This type of wind turbines is around for many centuries. The modern equivalent which is based on lift producing blades only exists for 30 years. In this period Airfoils for this application have been developed, but still much work can be done in this held. During this project a design process is developed with the purpose of improving the NACA 0018 Airfoil, which is commonly used in VAWT turbines. The aerodynamics involved in VAWT are investigated to find the design goals for the Airfoil Characteristics. Furthermore the currently used NACA 0018, which is used as the design reference, is investigated. The two main pillars of the design process are the RFOIL program and the VAWT simulation program. RFOIL is a panel method based program with boundary layer equations which can calculate the properties of 2D Airfoils. RFOIL gives accurate enough results to be a powerful design tool in the Reynolds number range from 300,000 to 700,000. The VAWT simulation program, written in MATLAB, calculates the performance of a VAWT using 2D Airfoil data. The final Matlab program allows to adjust the turbines geometry, to chose from multiple Airfoils and to set a dynamic stall model on or off. As such 2D Airfoil Characteristic from RFOIL or wind tunnel tests can be inserted to view the turbines performance with this Airfoil.

Birzer C. - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic stall on Airfoils exposed to constant pitch-rate motion
    AFMS, 2016
    Co-Authors: Arjomandi M., Kelso R., Birzer C.
    Abstract:

    Gust-like flow behavior is simulated using pitching Airfoils to represent the unpredictable nature of atmospheric turbulence on the blades of wind turbines. Angle of attack, reduced frequency and both NACA 0021 and NACA 0012 Airfoils are investigated using particle image velocimetry to assess their influence on the developed flow structure resulting from the ramp-up constant angular velocity motion. The pitch motion was shown to delay the onset of the stall vortex to high angles of attack, which is linked to increased lift. Moreover, increasing the reduced frequency reduced the rate of vortex growth as the angle of attack was increased. Development of a rear separation bubble with low velocity is noted during initial development of the dynamic stall process. Once the critical angle of attack is reached, initiation of the formation of the dynamic stall vortex is observed. Increased angular displacement resulted in the annihilation of the trailing edge vortices, by the initial stall vortex, which also coincided with vortex-induced separation leading to bluff body separation. Results from the current work show the presence of delayed separation and vortex formation on the upper surface of the Airfoil Characteristic to the dynamic stall process. The current work highlights the flow features responsible for enhanced lift, whilst shedding light on the development process for constant-pitch-rate motion about thick and thin Airfoil sections.R.R. Leknys, M. Arjomandi, R.M. Kelso and C. Birze