Induced drag prediction for wing-tail and canard configurations through numerical optimisation

1994 ◽  
Vol 98 (976) ◽  
pp. 199-206 ◽  
Author(s):  
G. Lombardi ◽  
A. Vicini
Keyword(s):  
Computational Procedure ◽  
Preliminary Design ◽  
Induced Drag ◽  
Drag Prediction ◽  
Aerodynamic Interference ◽  
Lifting Surfaces ◽  
Numerical Optimisation

Abstract A computational procedure has been developed in order to predict aerodynamic interference between lifting surfaces, and to devise configurations which best meet given aerodynamic requirements. The procedure, which couples an aerodynamic solver with a numerical optimisation routine, is useful in the preliminary design of aircraft. The essential features of the aerodynamic code and of the optimisation routine are described, along with the coupling criteria. Some of the most significant predictions obtained in induced-drag minimisation for wing-tail and canard configurations are described and discussed.

scholarly journals Wake-model effects on induced drag prediction of staggered boxwings

2021 ◽  
Author(s):  
Julian Schirra ◽  
William Bissonnette ◽  
Götz Bramesfeld
Keyword(s):  
Potential Flow ◽  
Euler Method ◽  
Higher Order ◽  
Flow Method ◽  
Induced Drag ◽  
Wake Effects ◽  
Drag Prediction ◽  
Wake Model ◽  
Lifting Surfaces ◽  
High Degree

For staggered boxwings the predictions of induced drag that rely on common potential-flow methods can be of limited accuracy. For example, linear, freestream-fixed wake models cannot resolve effects related to wake deflection and roll-up, which can have significant affects on the induced drag projection of these systems. The present work investigates the principle impact of wake modelling on the accuracy of induced drag prediction of boxwings with stagger. The study compares induced drag predictions of a higher-order potential-flow method that uses fixed and relaxed-wake models, and of an Euler-flow method. Positive-staggered systems at positive angles of attack are found to be particularly prone to higher-order wake effects due to vertical contraction of wakes trajectories, which results in smaller effective height-to-span ratios than compared with negative stagger and thus closer interactions between trailing wakes and lifting surfaces. Therefore, when trying to predict induced drag of positive staggered boxwings, only a potential-flow method with a fully relaxed-wake model will provide the high-degree of accuracy that rivals that of an Euler method while being computationally significantly more efficient. Keywords: wake-model; boxwing; induced drag; potential-flow theory

scholarly journals Wake-model effects on induced drag prediction of staggered boxwings

2021 ◽  
Author(s):  
Julian Schirra ◽  
William Bissonnette ◽  
Götz Bramesfeld
Keyword(s):  
Potential Flow ◽  
Euler Method ◽  
Higher Order ◽  
Flow Method ◽  
Induced Drag ◽  
Wake Effects ◽  
Drag Prediction ◽  
Wake Model ◽  
Lifting Surfaces ◽  
High Degree

For staggered boxwings the predictions of induced drag that rely on common potential-flow methods can be of limited accuracy. For example, linear, freestream-fixed wake models cannot resolve effects related to wake deflection and roll-up, which can have significant affects on the induced drag projection of these systems. The present work investigates the principle impact of wake modelling on the accuracy of induced drag prediction of boxwings with stagger. The study compares induced drag predictions of a higher-order potential-flow method that uses fixed and relaxed-wake models, and of an Euler-flow method. Positive-staggered systems at positive angles of attack are found to be particularly prone to higher-order wake effects due to vertical contraction of wakes trajectories, which results in smaller effective height-to-span ratios than compared with negative stagger and thus closer interactions between trailing wakes and lifting surfaces. Therefore, when trying to predict induced drag of positive staggered boxwings, only a potential-flow method with a fully relaxed-wake model will provide the high-degree of accuracy that rivals that of an Euler method while being computationally significantly more efficient. Keywords: wake-model; boxwing; induced drag; potential-flow theory

scholarly journals Aero-Structural Optimization of Joined-Wing Aircraft

2017 ◽  
Vol 2017 (4) ◽  
pp. 48-63
Author(s):  
Miłosz Kalinowski
Keyword(s):  
Structural Optimization ◽  
Search Algorithm ◽  
Optimization Methods ◽  
Global Search ◽  
Preliminary Design ◽  
Electric Aircraft ◽  
Modular Algorithm ◽  
Lifting Surfaces ◽  
Joined Wing ◽  
Aircraft Configurations

Abstract Joined-wing aircraft due to its energy characteristics is a suitable configuration for electric aircraft when designed properly. However, because of the specific for this aircraft phenomenons (e.g. static indeterminacy of structure, aerodynamic interference of lifting surfaces) it demands more complicated methods to model its behavior than a traditional aircraft configurations. For these reasons the aero-structural optimization process is proposed for joined-wing aircrafts that is suitable for preliminary design. The process is a global search, modular algorithm based on automatic geometry generator, FEM solver and aerodynamic panel method. The range of aircraft was assumed as an objective function. The algorithm was successfully tested on UAV aircraft. The improvement of 19% of total aircraft range is achieved in comparison to baseline aircraft. Time of evaluation of this global search algorithm is similar to the time characteristic for local optimization methods. It allows to reduce the time and costs of preliminary design of joined-wing.

SPLASH Nonlinear and Unsteady Free-Surface Analysis Code for Grand Prix Yacht Design

1997 ◽  
Author(s):  
Bruce S. Rosen ◽  
Joseph P. Laiosa
Keyword(s):  
Free Surface ◽  
Free Surface Flow ◽  
Inviscid Flow ◽  
Wave Drag ◽  
Surface Flow ◽  
Viscous Drag ◽  
Accurate Estimation ◽  
Following Seas ◽  
Induced Drag ◽  
Lifting Surfaces

The SPLASH free-surface potential flow panel code computer program is presented. The 3D flow theory and its numerical implementation are discussed. Some more conventional applications are reviewed, for steady flow past solid bodies, and for classical linearized free-surface flow. New free-surface capabilities are also described, notably, steady nonlinear solutions, and novel unsteady partially­nonlinear solutions in the frequency domain. The inviscid flow method treats both free-surface waves and lifting surfaces. The calculations yield predictions for complex interactions at heel and yaw such as wave drag due to lift, the effect of the free­surface on lift and lift-induced drag, and unsteady motions and forces in oblique or following seas. These are in addition to the usual predictions for the simpler effects considered separately, for example double-body lift and induced drag, and upright steady wave resistance or added resistance in head seas. For prediction of total resistance, the use of computed variable wetted areas and wetted lengths in a standard semi-empirical, handbook-type "viscous stripping" algorithm provides a more accurate estimation of viscous drag than is possible otherwise. Results from a variety of IACC and IMS yacht design studies, including comparisons with experimental data, support the conclusion that the free­surface panel code can be used for reliable and accurate prediction of sailboat performance.

Augmenting Aerodynamic Lift with Jet Lift

1961 ◽  
Vol 65 (612) ◽  
pp. 830-832 ◽  
Author(s):  
Paul D. Arthur ◽  
Edward T. Pitkin
Keyword(s):  
System Size ◽  
The Body ◽  
Minor Effect ◽  
Preliminary Design ◽  
Propulsive Efficiency ◽  
Design Studies ◽  
Lifting Surfaces ◽  
A Minor ◽  
Propulsive Jet ◽  
Aerodynamic Lift

Downward deflection of a propulsive jet may be employed to augment aerodynamic lift in an advantageous manner. In each situation there occurs a simple optimisation when the losses due to reduced propulsive efficiency are contrasted with the gains which accrue from jet lifting. Typical cases will be considered here for wing dominant configurations, i.e. cases where the lifting surfaces contribute most of the drag, with the body contributing but a minor effect. Variable geometry of both airframe and engine is implicitly assumed so that results may be applied to preliminary design studies which will determine the relative propulsion system size and wing area.

Far-Field Induced Drag Prediction Using Vorticity Confinement Technique

2014 ◽  
Vol 51 (6) ◽  
pp. 1953-1958 ◽  
Author(s):  
Troy Snyder ◽  
Alex Povitsky
Keyword(s):  
Far Field ◽  
Induced Drag ◽  
Vorticity Confinement ◽  
Drag Prediction

AEROELASTIC TAILORING OF ADVANCED COMPOSITE LIFTING SURFACES IN PRELIMINARY DESIGN

1976 ◽  
Author(s):  
F. AUSTIN ◽  
R. HADCOCK ◽  
D. HUTCHINGS ◽  
D. SHARP ◽  
S. TANG ◽  
...  
Keyword(s):  
Preliminary Design ◽  
Aeroelastic Tailoring ◽  
Advanced Composite ◽  
Lifting Surfaces

Use of Athena Vortex Lattice for Preliminary Hydrofoil Design

2015 ◽  
Author(s):  
Katelynne R. Burrell ◽  
Joshua P. Sykes ◽  
Timothy B. Dewhurst ◽  
Zhaohui Qin
Keyword(s):  
High Speed ◽  
Vortex Lattice ◽  
Design Tool ◽  
Preliminary Design ◽  
Reference Guide ◽  
The Past ◽  
Lifting Surfaces ◽  
Lift And Drag ◽  
Design Options ◽  
Short Time

The purpose of this paper is to demonstrate the extent to which the Athena Vortex Lattice program (AVL) is useful in the design of a hydrofoil system for a solar boat. Cedarville University has won the Solar Splash Collegiate World Championship of Solar Boating 8 times in the past 12 years, and was the top university in the Top Class of the 2012 DONG Energy Solar Challenge in the Netherlands. The three main events of the Solar Splash Competition are the high-speed Slalom and Sprint events, and the longer Endurance event. In the past Cedarville has attempted to design and use hydrofoils for the Endurance event without success. Computational Fluid Dynamics (CFD) analysis for a hydrofoil system was conducted by Neola Putnam (2013 team member) using ANSYS’s CFD software, Fluent. Putnam worked with single phase flow modeling 3D hydrofoils. Fluent analysis can be a long and complicated process requiring hours of meshing followed by hours of CPU time for analysis. AVL, as an alternative, is a less complicated program allowing for simple generation of a geometry file. This program also takes a comparatively short time to analyze the imported geometry file. Thus, if AVL reliably predicts lift and drag, it could be used as a preliminary design tool to quickly assess various design options. AVL is a program which models lifting surfaces as vortex lattice sheets to determine the flight characteristics of the surface. The program is written in Fortran and is an inviscid solver. The AVL3.30 User Primer is a reference guide on how to use the program and was used extensively by the authors of this paper when learning to use AVL. Cedarville University also partnered with the company Sea Land Aire Technologies Inc.in Jackson Michigan for aid in using AVL as a design tool. The tool was recommended to Cedarville University by Sea Land Aire as a product which might be of interest to our team in the design of a hydrofoil system. AVL is potentially beneficial to the Cedarville University Solar Boat team in the preliminary design phase of a hydrofoil system. The content of this paper demonstrates the correlation between results from AVL and Fluent analysis for a 2D NACA 4412 foil. Secondly, the paper demonstrates comparable results from AVL for 3Danalysiswith published experimental results. The following sections discuss the use of AVL as a preliminary design tool, and the overall recommendation of the authors as to further use of AVL by Cedarville University in the design of a hydrofoil system.

scholarly journals IMPLEMENTATION OF SEMI-EMPIRICAL MODELS TO ENHANCE THE ACCURACY OF PANEL METHODS FOR DRAG PREDICTION AT SUPERSONIC SPEEDS

2011 ◽  
Vol 12 (3) ◽  
Author(s):  
Abdulkareem Shafiq Mahdi Al-Obaidi
Keyword(s):  
Computer Program ◽  
Panel Method ◽  
Preliminary Design ◽  
Empirical Methods ◽  
Average Value ◽  
Panel Methods ◽  
Drag Prediction ◽  
Stall Angle ◽  
Semi Empirical ◽  
Base Drag

This paper introduces an attempt to enhance the accuracy of panel methods. A low-order panel method is selected and coupled with semi-empirical methods to enhance the accuracy of drag prediction of flying bodies at supersonic speeds. The semi-empirical methods are used to improve the accuracy of drag prediction by mathematical modelling of viscosity, base drag, and drag due to wing-body interference. Both methods were implemented by a computer program and validated against experimental and analytical results. The comparisons show that a considerable improvement has been achieved for the selected panel method for prediction of drag coefficients. In general, accuracy within an average value of -4.4% was obtained for the enhanced panel method. Such accuracy could be considered acceptable for the preliminary design stages of supersonic flying bodies such as projectiles and missiles. The developed computer program gives satisfactory results as long as the considered configurations are slender and the angles of attack are small (below stall angle).  ABSTRAK: Kertas kerja ini memperkenalkan percubaan untuk  mempertingkatkan ketepatan kaedah panel. Kaedah panel tertib rendah telah dipilih dan digabungkan dengan kaedah separa empirik untuk mempertingkatkan ketepatan ramalan seret objek terbang pada kelajuan supersonik. Kaedah semi empirikal yang digunakan untuk meningkatkan ketepatan jangkaan seret menggunakan model matematik bagi kelikatan, seretan dasar, dan  seretan disebabkan  oleh badan sayap interferens. Kedua-dua kaedah dijalankan menggunakan program komputer dan disah berdasarkan keputusan uji kaji dan analisis. Perbandingan keputusan menunjukkan peningkatan yang mendadak diperolehi melalui kaedah panel yang telah dipilih sebagai jangkaan pekali seret. Secara umumnya, ketepatan yang melingkungi nilai purata sebanyak -4.4% telah diperolehi daripada kaedah peningkatan panel. Keputusan sebegini boleh diterima untuk peringkat reka bentuk permulaan bagi objek terbang supersonik seperti projektil dan misil. Program komputer yang direka memberikan keputusan yang memuaskan selagi konfigurasi yang dipilih adalah kecil dan sudut serangan adalah rendah (di bawah sudut tegun).

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