scholarly journals Software development for subsonic aircraft’s unsteady longitudinal stability derivatives calculation

2005 ◽  
Vol 32 (4) ◽  
pp. 319-340 ◽  
Author(s):  
Nikola Maricic
Keyword(s):  
Method Of Images ◽  
Lattice Method ◽  
Aerodynamic Stability ◽  
Slender Body Theory ◽  
Stability Derivatives ◽  
Doublet Lattice Method ◽  
Body Theory ◽  
General Configuration ◽  
Finite Element Methodology ◽  
Good Agreement

Subsonic general configuration aircrafts? unsteady longitudinal aerodynamic stability derivatives can be estimated using finite element methodology based on the Doublet Lattice Method (DLM), the Slender Body Theory (SBT) and the Method of Images (MI). Applying this methodology, software DERIV is developed. The obtained results from DERIV are compared to NASTRAN examples HA21A and HA75H. A good agreement is achieved.

scholarly journals Numerical estimation of aircrafts' unsteady lateral-directional stability derivatives

2006 ◽  
Vol 33 (4) ◽  
pp. 311-337
Author(s):  
N.L. Maricic
Keyword(s):  
Cross Sections ◽  
Vertical Plane ◽  
Lattice Method ◽  
Slender Body Theory ◽  
Directional Stability ◽  
Load Distributions ◽  
Stability Derivatives ◽  
Lifting Surfaces ◽  
Body Theory ◽  
Control Surfaces

A technique for predicting steady and oscillatory aerodynamic loads on general configuration has been developed. The prediction is based on the Doublet-Lattice Method, Slender Body Theory and Method of Images. The chord and span wise loading on lifting surfaces and longitudinal bodies (in horizontal and vertical plane) load distributions are determined. The configuration may be composed of an assemblage of lifting surfaces (with control surfaces) and bodies (with circular cross sections and a longitudinal variation of radius). Loadings predicted by this method are used to calculate (estimate) steady and unsteady (dynamic) lateral-directional stability derivatives. The short outline of the used methods is given in [1], [2], [3], [4] and [5]. Applying the described methodology software DERIV is developed. The obtained results from DERIV are compared to NASTRAN examples HA21B and HA21D from [4]. In the first example (HA21B), the jet transport wing (BAH wing) is steady rolling and lateral stability derivatives are determined. In the second example (HA21D), lateral-directional stability derivatives are calculated for forward- swept-wing (FSW) airplane in antisymmetric quasi-steady maneuvers. Acceptable agreement is achieved comparing the results from [4] and DERIV.

Two-Dimensional Apparent Masses for Cross-Flow Sections of Wing-Store Configurations

1982 ◽  
Vol 49 (3) ◽  
pp. 471-475
Author(s):  
M.-K. Huang
Keyword(s):  
Approximate Method ◽  
Cross Flow ◽  
Slender Body ◽  
Two Dimensional ◽  
Aerodynamic Stability ◽  
Slender Body Theory ◽  
Rolling Moment ◽  
Stability Derivatives ◽  
The Cross ◽  
Body Theory

On the basis of the assumption that the external stores are small compared with the wing, an approximate method has been developed for estimation of two-dimensional apparent masses for the cross-flow sections of wing-store combinations. The results obtained may be applicable to the analysis of the effects of the stores on the aerodynamic stability derivatives in slender-body theory. The theory has also been applied to estimate the rolling moment due to sideslip for high-wing configurations. The presented results are in agreement with those of other investigations.

On an Approximate Method of Calculating Pressures on Non-lifting Head Shapes at Supersonic Speeds

1955 ◽  
Vol 6 (1) ◽  
pp. 31-45
Author(s):  
H. K. Zienkiewicz
Keyword(s):  
Method Of Characteristics ◽  
Order Theory ◽  
Stagnation Pressure ◽  
Slender Body Theory ◽  
Pressure Losses ◽  
The Method Of Characteristics ◽  
Curvature Approximation ◽  
Body Theory ◽  
Theory And Experiment ◽  
Good Agreement

SummarySlender-body theory is used to derive the ogive of curvature approximation for very slender, pointed, convex head shapes at supersonic speeds. Results of application of this approximation, together with the λ-method for circular arc ogives, to a variety of non-slender head shapes show very good agreement with the method of characteristics, van Dyke's second-order theory and experiment. Good agreement with the method of characteristics and with experiment is obtained even in cases when the stagnation pressure losses across the nose shock wave are not negligible.

Slender-body theory for steady sheared plumes in very viscous fluid

2008 ◽  
Vol 612 ◽  
pp. 21-44 ◽  
Author(s):  
ROBERT J. WHITTAKER ◽  
JOHN R. LISTER
Keyword(s):  
Simple Model ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Experimental Studies ◽  
Slender Body ◽  
Slender Body Theory ◽  
Dimensionless Parameters ◽  
Dynamical Regimes ◽  
Body Theory ◽  
Good Agreement

A simple model based on slender-body theory is developed to describe the deflection of a steady plume by shear flow in very viscous fluid of the same viscosity. The key dimensionless parameters measuring the relative strengths of the shear, diffusion and source flux are identified, which allows a number of different dynamical regimes to be distinguished. The predictions of the model show good agreement with many, but not all, observations from previous experimental studies. Possible reasons for the discrepancies are discussed.

Inhomogeneous distribution of a rigid fibre undergoing rectilinear flow between parallel walls at high Péclet numbers

2009 ◽  
Vol 630 ◽  
pp. 267-298 ◽  
Author(s):  
JOONTAEK PARK ◽  
JASON E. BUTLER
Keyword(s):  
Simple Shear Flow ◽  
Inhomogeneous Distribution ◽  
Slender Body Theory ◽  
Shear Rates ◽  
Net Migration ◽  
High Shear Rates ◽  
Fibre Suspensions ◽  
Parabolic Flow ◽  
Body Theory ◽  
Good Agreement

We use slender-body theory to simulate a rigid fibre within simple shear flow and parabolic flow at zero Reynolds number and high Péclet numbers (weak Brownian motion). Hydrodynamic interactions of bulk fibres with the bounding walls are included using previously developed methods (Harlen, Sundararajakumar & Koch, J. Fluid Mech., vol. 388, 1999, pp. 355–388; Butler & Shaqfeh, J. Fluid Mech., vol. 468, 2002, pp. 205–237). We also extend a previous analytic theory (Park, Bricker & Butler, Phys. Rev. E, vol. 76, 2007, 04081) predicting the centre-of-mass distribution of rigid fibre suspensions undergoing rectilinear flow near a wall to compare the steady and transient distributions. The distributions obtained by the simulation and theory are in good agreement at sufficiently high shear rates, validating approximations made in the theory which predicts a net migration of the rigid fibres away from the walls due to a hydrodynamic lift force. The effect of the inhomogeneous distribution on the effective stress is also investigated.

On the Low Aspect Ratio Oscillating Rectangular Wing in Supersonic Flow

1953 ◽  
Vol 4 (2) ◽  
pp. 231-244 ◽  
Author(s):  
John W. Miles
Keyword(s):  
Supersonic Flow ◽  
Aspect Ratio ◽  
Velocity Potential ◽  
Fourth Power ◽  
Slender Body Theory ◽  
Single Degree ◽  
Low Aspect Ratio ◽  
Stability Derivatives ◽  
The Laplace Transform ◽  
Body Theory

SummaryThe Laplace transform of the lift distribution on an oscillating rectangular wing in a supersonic flow is obtained by separating the linearised equation for the velocity potential in elliptic (cylindrical) co-ordinates. The results for the case of no spanwise distortion are expanded in ascending powers of the aspect ratio in order to compare with the slender body theory, and the longitudinal stability derivatives are calculated. It is found that at either supersonic or transonic speeds single-degree-offreedom instability in pitch is impossible insofar as the fourth power of the aspect ratio is neglected.

A hydrodynamical analysis of fish turning manoeuvres

1972 ◽  
Vol 182 (1066) ◽  
pp. 59-72 ◽  
Keyword(s):  
Present Theory ◽  
Inviscid Fluid ◽  
Centre Of Mass ◽  
Turning Process ◽  
Slender Body Theory ◽  
Turning Mechanism ◽  
Three Stages ◽  
Straight Lines ◽  
Body Theory ◽  
Good Agreement

Slender body theory, adapted here to the study of unsteady, curvilinear large amplitude movements in an inviscid fluid, is applied to the study of the turning mechanism in fishes. The vortex wake is represented by the circulation shed from the fins in the present theory. Examination of filmed sequences of turning fish show that the turning process includes three stages, distinguished by different movements of the centre of mass. In the first and third stages the centre of mass moves in straight lines in the initial and final directions of swimming while in the middle period it moves along an approximately circular connecting arc. The forces and moments acting on the fish, calculated by the present method are found to be in good agreement with these experimental observations.

Force and Power Estimation in Fish-Like Locomotion Using a Vortex-Lattice Method

1999 ◽  
Vol 122 (2) ◽  
pp. 239-253 ◽  
Author(s):  
H. Kagemoto ◽  
M. J. Wolfgang ◽  
D. K. P. Yue ◽  
M. S. Triantafyllou
Keyword(s):  
Vortex Lattice ◽  
Practical Interest ◽  
Power Estimation ◽  
Quantitative Agreement ◽  
Slender Body ◽  
Lattice Method ◽  
Slender Body Theory ◽  
Vortex Lattice Method ◽  
Linearized Theory ◽  
Body Theory

The forces and power needed for propelling at constant speed an actively swimming flexible fish-like body are calculated. A vortex-lattice method based on a linearized theory is employed and the results are compared against slender body theory predictions, as well as experimental data from an eight-link robotic instrument, the RoboTuna. Qualitative agreement is found between our method and slender body theory; with quantitative agreement over certain parametric ranges and disagreement for other ranges of practical interest. The present linearized vortex lattice calculations predict the power needed for propelling the RoboTuna with less than 20 percent error in most experiments conducted. [S0098-2202(00)01202-5]

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