Effect of corrugated skins on the aerodynamic performance of the cambered airfoils

2018 ◽  
Vol 35 (3) ◽  
pp. 1567-1582 ◽  
Author(s):  
Masoud Kharati-koopaee ◽  
Mahmood Fallahzadeh-abarghooee
Keyword(s):  
Drag Coefficient ◽  
Design Methodology ◽  
Reynolds Numbers ◽  
Numerical Approach ◽  
Aerodynamic Performance ◽  
Content Type ◽  
Lift Curve ◽  
Finite Volume Approach ◽  
Naca 0012 ◽  
Relative Curve

Purpose This paper aims to study the effect of corrugated skins on the aerodynamic performance of the cambered NACA 0012 airfoils at different corrugations parameters, maximum cambers, Reynolds numbers and maximum camber locations. Design/methodology/approach In this work, numerical approach is concerned, and results are obtained based on the finite volume approach. To characterize the effect of corrugated skins, the NACA 0012-corrugated airfoil section is chosen as the base airfoil, and different cambered corrugated airfoil sections are obtained by inclusion the camber to the base airfoil. In this research, the corrugation shape is a sinusoidal wave and corrugated skins are in the aft 30 per cent of airfoil chord. To investigate the effect of corrugations on the cambered sections, the drag coefficient and averaged lift curve slope for the corrugated airfoils are compared to those of the corresponding smooth sections. Findings Results indicate that the effect of increase in the maximum camber and also Reynolds number on the relative zero-incidence drag coefficient is of little importance at low corrugation amplitudes, whereas at high corrugation, amplitude results in different behaviors. It is found that as the maximum camber increases, the deterioration in the relative curve slope introduced by corrugated skins is reduced, and reduction in this deterioration is significant for high corrugation amplitudes airfoils. It is shown that an increase in the maximum camber location has nearly no effect on the relative zero-incidence drag coefficient and also relative lift curve slope. Originality/value The outcome of the present research provides the clues for better understanding of the effect of different corrugations parameters on the aerodynamic performance of the unmanned air vehicles to have as high aerodynamic performance as possible in different mission profiles of such vehicles.

Aerodynamic study of corrugated skins for morphing wing applications

2010 ◽  
Vol 114 (1154) ◽  
pp. 237-244 ◽  
Author(s):  
C. Thill ◽  
J. D. Downsborough ◽  
S. J. Lai ◽  
I. P. Bond ◽  
D. P. Jones
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Smooth Surface ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Potential Solution ◽  
Morphing Wing ◽  
Lift Curve ◽  
Length Changes ◽  
Wing Skin

AbstractCorrugated structures offer a potential solution for morphing wing skin applications due to their anisotropic behaviour that allows chordwise camber and length changes. Aerofoils with corrugated skins in the aft 1/3 of the chordwise section have been studied experimentally and computationally using various corrugation shapes and forms (sinusoidal, trapezoidal and triangular) at different Reynolds numbers. The study showed that the aerodynamic performance is highly dependent on corrugation amplitude, wavelength, gradient (combination of amplitude and wavelength) and Reynolds number. Evidence is given highlighting that penalties for having a non-smooth surface in the aft 1/3 of the chordwise section of an aerofoil can be eliminated for the lift curve slope and minimised for the zero lift drag coefficient.

Frequency dependent resistance calculation of multiple conductors

2017 ◽  
Vol 36 (5) ◽  
pp. 1396-1410
Author(s):  
Tomislav Župan ◽  
Bojan Trkulja
Keyword(s):  
Design Methodology ◽  
Numerical Approach ◽  
Effective Resistance ◽  
Proximity Effects ◽  
The Finite Element Method ◽  
Frequency Range ◽  
Frequency Dependent ◽  
Content Type ◽  
Electromagnetic Devices ◽  
Practical Implications

Purpose The purpose of this paper is to present a method for calculating frequency-dependent resistance when multiple current-carrying conductors are present. Design/methodology/approach Analytical and numerical formulations are presented. Both skin- and proximity-effects are considered in the numerical approach, whereas only skin-effect can be taken into account in analytical equations. The calculation is done using a self-developed integral equation-based field solver. The results are benchmarked using professional software based on the finite element method (FEM). Findings Results from the numerical approach are in agreement with FEM-based software throughout the whole frequency range. Analytical formulations yield unsatisfactory results in higher frequency range. When multiple conductors are mutually relatively close, the proximity-effect has an impact on effective resistance and has to be taken into account. Research limitations/implications The methodology is presented using axially symmetrical conductors. However, the same procedure can be developed for straight conductors as well. Practical implications Presented fast and stable procedure can be used in most electromagnetic devices when frequency-dependent resistance needs to be precisely determined. Originality/value The value of the presented numerical methodology lies in its ability to take both skin- and proximity-effects into account. As conductors are densely packed in most electromagnetic devices, both effects influence the effective resistance. The method can be easily implemented using a self-developed solver and yields satisfactory results.

Three weighted residual methods based on Jeffery-Hamel flow

2014 ◽  
Vol 24 (3) ◽  
pp. 654-668 ◽  
Author(s):  
D.D. Ganji ◽  
Mohammad Hatami
Keyword(s):  
Analytical Methods ◽  
Design Methodology ◽  
Least Square Method ◽  
Numerical Approach ◽  
Least Square ◽  
The Other ◽  
Governing Equations ◽  
Science And Engineering ◽  
Content Type ◽  
Linear Differential

Purpose – The purpose of this paper is to demonstrate the eligibility of the weighted residual methods (WRMs) applied to Jeffery-Hamel Flow. Selecting the most appropriate method among the WRMs and discussing about Jeffery-Hamel flow's treatment in divergent and convergent channels are the other important purposes of the present research. Design/methodology/approach – Three analytical methods (collocation, Galerkin and least square method) have been applied to solve the governing equations. The reliability of the methods is also approved by a comparison made between the forth order Runge-Kutta numerical method. Findings – The obtained solutions revealed that WRMs can be simple, powerful and efficient techniques for finding analytical solutions in science and engineering non-linear differential equations. Originality/value – It could be considered as a first endeavor to use the solution of the Jeffery-Hamel flow using these kind of analytical methods along with the numerical approach.

A numerical approach for a class of astrophysics equations using piecewise spectral-variational iteration method

2017 ◽  
Vol 27 (2) ◽  
pp. 358-378 ◽  
Author(s):  
Mohammad Heydari ◽  
Ghasem Barid Loghmani ◽  
Abdul-Majid Wazwaz
Keyword(s):  
Iteration Method ◽  
Design Methodology ◽  
Variational Iteration Method ◽  
Mathematical Physics ◽  
Numerical Approach ◽  
Nonlinear System Of Equations ◽  
Content Type ◽  
Variational Iteration ◽  
Analytical Integration ◽  
Chebyshev Interpolation

Purpose The main purpose of this paper is to implement the piecewise spectral-variational iteration method (PSVIM) to solve the nonlinear Lane-Emden equations arising in mathematical physics and astrophysics. Design/methodology/approach This method is based on a combination of Chebyshev interpolation and standard variational iteration method (VIM) and matching it to a sequence of subintervals. Unlike the spectral method and the VIM, the proposed PSVIM does not require the solution of any linear or nonlinear system of equations and analytical integration. Findings Some well-known classes of Lane-Emden type equations are solved as examples to demonstrate the accuracy and easy implementation of this technique. Originality/value In this paper, a new and efficient technique is proposed to solve the nonlinear Lane-Emden equations. The proposed method overcomes the difficulties arising in calculating complicated and time-consuming integrals and terms that are not needed in the standard VIM.

Dynamic analysis of a cracked bar by the method of characteristics

2019 ◽  
Vol 10 (4) ◽  
pp. 438-453 ◽  
Author(s):  
Hillal Ayas ◽  
Mohamed Chabaat ◽  
Lyes Amara
Keyword(s):  
Design Methodology ◽  
Method Of Characteristics ◽  
Numerical Approach ◽  
Crack Size ◽  
Equation Of Motion ◽  
Content Type ◽  
Reflected Waves ◽  
First Order ◽  
The Method Of Characteristics ◽  
The Difference

Purpose The purpose of this paper is to introduce a new numerical approach for studying a cantilever bar having a transverse crack. The crack is modeled by an elastic longitudinal spring with a stiffness K according to Castiglione’s theorem. Design/methodology/approach The bar is excited by different longitudinal impulse forces. The considered problem based on the differential equation of motion is solved by the method of characteristics (MOC) after splitting the second-order motion equation into two first-order equivalent equations. Findings In this study, effects of the crack size and crack’s position on the reflected waves from the crack are investigated. The results indicate that the presence of the crack in the cantilever bar generates additional waves caused by the reflection of the incident wave by the crack. Originality/value A numerical approach developed in this paper is used for detecting the extent of the damage in cracked bars by the measurement of the difference between the dynamic response of an uncracked bar and a cracked bar.

UAV icing: the influence of airspeed and chord length on performance degradation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Richard Hann ◽  
Tor Arne Johansen
Keyword(s):  
Reynolds Number ◽  
Reynolds Numbers ◽  
Aerodynamic Performance ◽  
Performance Degradation ◽  
Unmanned Aircraft ◽  
Chord Length ◽  
Ice Accretion ◽  
Content Type ◽  
Ice Accretions ◽  
Ice Shapes

Purpose The main purpose of this paper is to investigate the effects of icing on unmanned aerial vehicles (UAVs) at low Reynolds numbers and to highlight the differences to icing on manned aircraft at high Reynolds numbers. This paper follows existing research on low Reynolds number effects on ice accretion. This study extends the focus to how variations of airspeed and chord length affect the ice accretions, and aerodynamic performance degradation is investigated. Design/methodology/approach A parametric study with independent variations of airspeed and chord lengths was conducted on a typical UAV airfoil (RG-15) using icing computational fluid dynamic methods. FENSAP-ICE was used to simulate ice shapes and aerodynamic performance penalties. Validation was performed with two experimental ice shapes obtained from a low-speed icing wind tunnel. Three meteorological conditions were chosen to represent the icing typologies of rime, glaze and mixed ice. A parameter study with different chord lengths and airspeeds was then conducted for rime, glaze and mixed icing conditions. Findings The simulation results showed that the effect of airspeed variation depended on the ice accretion regime. For rime, it led to a minor increase in ice accretion. For mixed and glaze, the impact on ice geometry and penalties was substantially larger. The variation of chord length had a substantial impact on relative ice thicknesses, ice area, ice limits and performance degradation, independent from the icing regime. Research limitations/implications The implications of this manuscript are relevant for highlighting the differences between icing on manned and unmanned aircraft. Unmanned aircraft are typically smaller and fly slower than manned aircraft. Although previous research has documented the influence of this on the ice accretions, this paper investigates the effect on aerodynamic performance degradation. The findings in this work show that UAVs are more sensitive to icing conditions compared to larger and faster manned aircraft. By consequence, icing conditions are more severe for UAVs. Practical implications Atmospheric in-flight icing is a severe risk for fixed-wing UAVs and significantly limits their operational envelope. As UAVs are typically smaller and operate at lower airspeeds compared to manned aircraft, it is important to understand how the differences in airspeed and size affect ice accretion and aerodynamic performance penalties. Originality/value Earlier work has described the effect of Reynolds number variations on the ice accretion characteristics for UAVs. This work is expanding on those findings by investigating the effect of airspeed and chord length on ice accretion shapes separately. In addition, this study also investigates how these parameters affect aerodynamic performance penalties (lift, drag and stall).

Structural dynamics of a gyrocopter: numerical approach in some emergency cases

2018 ◽  
Vol 90 (4) ◽  
pp. 699-710
Author(s):  
Adam Dacko ◽  
Pawel Borkowski ◽  
Lukasz Pawel Lindstedt ◽  
Cezary Rzymkowski ◽  
Miroslaw Rodzewicz
Keyword(s):  
Design Methodology ◽  
Structural Response ◽  
Numerical Approach ◽  
Design Parameters ◽  
Dynamic Problems ◽  
Content Type ◽  
Modeling And Analysis ◽  
Dynamic Events ◽  
Rescue System ◽  
Practical Implications

Purpose This paper aims to present the assumptions, analysis and sample results of numerical modeling and analysis of dynamic events encountered in emergency cases during deployment of parachute rescue system (PRS) and hard landing of a small gyrocopter. The optimal design requires knowledge of structural loads and structural response – the information obtained often from experiment. Numerical simulation is presented as an alternative tool for estimating these data. Design/methodology/approach Structural analyses were performed using MSC.Nastran. Multibody simulations were done using MADYMO system. Findings Initial design parameters were evaluated and verified in numerical simulations. Some of the resulting conclusions were proven during the test flights. Practical implications Some chosen results of simulation of dynamic problems are presented. They can be useful as reference values for similar cases for light aircraft analysis. Originality/value The paper presents an alternative way of assessing structural response parameters in the case of emergency dynamic events of usage of PRS. The results can be used in other projects.

A parametric study on the droplet detachment process from the ceiling under the effect of gravity

2019 ◽  
Vol 36 (2) ◽  
pp. 445-465
Author(s):  
Jai Manik ◽  
Amaresh Dalal ◽  
Ganesh Natarajan
Keyword(s):  
Weber Number ◽  
Design Methodology ◽  
Density Ratio ◽  
Two Dimensions ◽  
Volume Of Fluid Method ◽  
Governing Equations ◽  
Content Type ◽  
Finite Volume Approach ◽  
Droplet Detachment ◽  
Initial Droplet Size

Purpose The purpose of this paper is to numerically investigate the effect of various parameters such as density ratio, surface wettabilities and Weber number on the droplet dripping and detachment process. Design/methodology/approach By using algebraic volume of fluid method, the governing equations are solved using a collocated finite volume approach in two-dimensions. Findings The results indicate that, for small densities of droplet, it adheres to the surface except when the surface is hydrophobic, while an increase in Weber number or presence of an additional droplet in the vicinity led to detachment. Originality/value The paper explores various characteristics of a droplet when two competing forces, namely, gravity and surface tension, act simultaneously. The detachment is observed for a given initial droplet size, as it becomes denser in an uniform gravitational field. The effect of droplet affinity for two droplets is also presented using the simulations.

Aerodynamic performance improvement of a canard control missile

2017 ◽  
Vol 89 (6) ◽  
pp. 871-878 ◽  
Author(s):  
M. Tahani ◽  
M. Masdari ◽  
M. Kazemi
Keyword(s):  
Aspect Ratio ◽  
Drag Coefficient ◽  
Cross Section ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Slender Body Theory ◽  
Content Type ◽  
Drag Ratio ◽  
Body Theory ◽  
Lift To Drag Ratio

Purpose This paper aims to analyze the influence of the changings in geometrical parameters on the aerodynamic performance of the control canard projectiles. Design/methodology/approach Because of the mentioned point, the range of projectiles increment has a considerable importance, and the design algorithm of a control canard projectile was first written. Then, were studied the effects of canard geometric parameters such as aspect ratio, taper ratio and deflectable nose on lift to drag coefficient ratio, static margin based on the slender body theory and cross section flow. Findings The code results show that aspect ratio increment, results in an increase in lift-to-drag ratio of the missile, but increase in canard taper ratio results in increasing of lift-to-drag ratio at 1° angle of attack, while during increasing the canard taper ratio up to 0.67 at 4° angle of attack, lift to drag first reaches to maximum and then decreases. Also, static margin decreases with canard taper ratio and aspect ratio increment. The developed results for this type of missile were compared with same experimental and computational fluid dynamic (CFD) results and appreciated agreement with other results at angles of attack between 0° and 6°. Practical implications To design a control canard missile, the effect of each geometric parameter of canard needs to be estimated. For this purpose, the suitable algorithm is used. In this paper, the effects of canard geometric parameters, such as aspect ratio, taper ratio and deflectable nose on lift-to-drag coefficient ratio and static margin, were studied with help of the slender body theory and cross-section flow. Originality/value The contribution of this paper is to predict the aerodynamic characteristics for the control canard missile. In this study, the effect of the design parameter on aerodynamic characteristics can be estimated, and the effect of geometrical characteristics has been analyzed with a suitable algorithm. Also, the best lift-to-drag coefficient for the NASA Tandem Control Missile at Mach 1.75 was selected at various angles of attack. The developed results for this type of missile were compared with same experimental and CFD results.

Natural convective heat transfer in the air-filled interstice between inclined concentric hemispheres

2017 ◽  
Vol 27 (10) ◽  
pp. 2375-2384 ◽  
Author(s):  
Nacim Alilat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Design Methodology ◽  
Numerical Approach ◽  
Constant Heat Flux ◽  
Horizontal Position ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
Volume Method

Purpose The main purpose of this work is to quantify the convective heat transfer occurring between two inclined and concentric hemispheres. Design/methodology/approach The inner one is an electronic assembly generating a constant heat flux during operation. The outer hemisphere is maintained isothermal at cold temperature. The interstitial space is air-filled. The base of the equipment can be inclined with respect to the horizontal plane by an angle ranging from 0° (horizontal position with dome faced upwards) to 180° (horizontal position with dome faced downwards). Findings Nusselt–Rayleigh correlations are proposed for several configurations obtained by varying the generated power and the base inclination. The large resulting Rayleigh number ranging between 2.4 × 105 and 1.7 × 107 allows using these new and original correlations in various engineering fields, such as electronics in the present work. The calculations are realized by means of a 3D numerical approach based on the finite volume method. Originality/value The geometry and the thermal boundary conditions considered in the present survey are suitable for applications in many engineering areas.

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