Correction: Reiswich et al. Effect of Flexible Flaps on Lift and Drag of Laminar Profile Flow. Energies 2020, 13, 1077

This paper presents new results concerning the aerodynamics of the Ahmed body fitted with a non-flat underbody diffuser. As in previous investigations performed, the angle and the length of the diffuser are the parameters systematically varied within ranges relevant for a hatchback passenger car. Coefficients of lift and drag are compared with the values obtained for the flat underbody diffuser, and the results reveal significant improvements concerning aerodynamic characteristics of body.

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A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽

10.3390/sym12050828 ◽

2020 ◽

Vol 12 (5) ◽

pp. 828

Author(s):

Igor Rodriguez-Eguia ◽

Iñigo Errasti ◽

Unai Fernandez-Gamiz ◽

Jesús María Blanco ◽

Ekaitz Zulueta ◽

...

Keyword(s):

Aerodynamic Coefficients ◽

Trailing Edge ◽

High Lift ◽

Trailing Edge Flaps ◽

Artificial Neural Network Ann ◽

Lift And Drag ◽

Artificial Neuronal Network ◽

Naca 0012 ◽

Drag Ratio ◽

Lift To Drag Ratio

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

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Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

Journal of Marine Science and Engineering ◽

10.3390/jmse9010014 ◽

2020 ◽

Vol 9 (1) ◽

pp. 14

Author(s):

Gianluca Zitti ◽

Nico Novelli ◽

Maurizio Brocchini

Keyword(s):

Numerical Model ◽

Laboratory Experiments ◽

Numerical Models ◽

Offshore Structures ◽

Fish Farm ◽

Maximum Displacement ◽

Drag Forces ◽

Real Size ◽

Lift And Drag ◽

Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

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Numerical study of geometric morphing wings of the 1303 UCAV

The Aeronautical Journal ◽

10.1017/aer.2021.15 ◽

2021 ◽

pp. 1-17

Author(s):

B. Nugroho ◽

J. Brett ◽

B.T. Bleckly ◽

R.C. Chin

Keyword(s):

Flight Control ◽

Numerical Study ◽

Aerodynamic Characteristics ◽

Morphing Wing ◽

Rolling Moment ◽

Wide Range ◽

Morphing Wings ◽

Wing Geometry ◽

Lift And Drag ◽

Wing Morphing

ABSTRACT Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

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Machine learning–based reduced-order modeling of hydrodynamic forces using pressure mode decomposition

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410021999864 ◽

2021 ◽

pp. 095441002199986

Author(s):

Hassan F Ahmed ◽

Hamayun Farooq ◽

Imran Akhtar ◽

Zafar Bangash

Keyword(s):

Machine Learning ◽

Short Term Memory ◽

Stokes Equations ◽

Decomposition Analysis ◽

Hydrodynamic Forces ◽

Reduced Order Modeling ◽

Navier Stokes ◽

Reduced Order ◽

Mode Decomposition ◽

Lift And Drag

In this article, we introduce a machine learning–based reduced-order modeling (ML-ROM) framework through the integration of proper orthogonal decomposition (POD) and deep neural networks (DNNs), in addition to long short-term memory (LSTM) networks. The DNN is utilized to upscale POD temporal coefficients and their respective spatial modes to account for the dynamics represented by the truncated modes. In the second part of the algorithm, temporal evolution of the POD coefficients is obtained by recursively predicting their future states using an LSTM network. The proposed model (ML-ROM) is tested for flow past a circular cylinder characterized by the Navier–Stokes equations. We perform pressure mode decomposition analysis on the flow data using both POD and ML-ROM to predict hydrodynamic forces and demonstrate the accuracy of the proposed strategy for modeling lift and drag coefficients.

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Flight performance monitoring with optimal filtering applications

The Aeronautical Journal ◽

10.1017/aer.2019.142 ◽

2019 ◽

Vol 124 (1272) ◽

pp. 170-188

Author(s):

V. A. Deo ◽

F. Silvestre ◽

M. Morales

Keyword(s):

Kalman Filter ◽

Performance Monitoring ◽

The Body ◽

Flight Performance ◽

Performance Parameters ◽

Sideslip Angle ◽

Fuel Flow ◽

Aircraft Performance ◽

Lift And Drag

ABSTRACTThis work presents an alternative methodology for monitoring flight performance during airline operations using the available inboard instrumentation system. This method tries to reduce the disadvantages of the traditional specific range monitoring technique where instrumentation noise and cruise stabilisation conditions affect the quality of the performance monitoring results. The proposed method consists of using an unscented Kalman filter for aircraft performance identification using Newton’s flight dynamic equations in the body X, Y and Z axis. The use of the filtering technique reduces the effect of instrumentation and process noise, enhancing the reliability of the performance results. Besides the better quality of the monitoring process, using the proposed technique, additional results that are not possible to predict with the specific range method are identified during the filtering process. An example of these possible filtered results that show the advantages of this proposed methodology are the aircraft fuel flow offsets, as predicted in the specific range method, but also other important aircraft performance parameters as the aircraft lift and drag coefficients (CL and CD), sideslip angle (β) and wind speeds, giving the operator a deeper understanding of its aircraft operational status and the possibility to link the operational monitoring results to aircraft maintenance scheduling. This work brings a cruise stabilisation example where the selected performance monitoring parameters such as fuel flow factors, lift and drag bias, winds and sideslip angle are identified using only the inboard instrumentation such as the GPS/inertial sensors, a calibrated anemometric system and the angle-of-attack vanes relating each flight condition to a specific aircraft performance monitoring result. The results show that the proposed method captures the performance parameters by the use of the Kalman filter without the need of a strict stabilisation phase as it is recommended in the traditional specific range method, giving operators better flexibility when analysing and monitoring fleet performance.

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Corrigendum to Lift and drag force on a spherical particle in a viscoelastic shear flow Journal of Non-Newtonian Fluid Mechanics 280 (2020) 104279

Journal of Non-Newtonian Fluid Mechanics ◽

10.1016/j.jnnfm.2020.104323 ◽

2020 ◽

Vol 282 ◽

pp. 104323

Author(s):

Anni Zhang ◽

William L. Murch ◽

Jonas Einarsson ◽

Eric S.G. Shaqfeh

Keyword(s):

Shear Flow ◽

Fluid Mechanics ◽

Spherical Particle ◽

Drag Force ◽

Newtonian Fluid ◽

Lift And Drag

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Design and Analysis of a Wind Turbine Blade with Dimples to Enhance the Efficiency through CFD with ANSYS R16.0

MATEC Web of Conferences ◽

10.1051/matecconf/201820702004 ◽

2018 ◽

Vol 207 ◽

pp. 02004

Author(s):

M. Rajaram Narayanan ◽

S. Nallusamy ◽

M. Ragesh Sathiyan

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Wind Turbine ◽

Wind Turbines ◽

Turbine Blades ◽

Electrical Energy ◽

Optimum Combination ◽

Surface Topology ◽

Wind Turbine Blades ◽

Lift And Drag

In the global scenario, wind turbines and their aerodynamics are always subjected to constant research for increasing their efficiency which converts the abundant wind energy into usable electrical energy. In this research, an attempt is made to increase the efficiency through the changes in surface topology of wind turbines through computational fluid dynamics. Dimples on the other hand are very efficient in reducing air drag as is it evident from the reduction of drag and increase in lift in golf balls. The predominant factors influencing the efficiency of the wind turbines are lift and drag which are to be maximized and minimized respectively. In this research, surface of turbine blades are integrated with dimples of various sizes and arrangements and are analyzed using computational fluid dynamics to obtain an optimum combination. The analysis result shows that there is an increase in power with about 15% increase in efficiency. Hence, integration of dimples on the surface of wind turbine blades has helped in increasing the overall efficiency of the wind turbine.

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