A Three-Dimensional Boundary-Layer Method for Flow over Delta Wings with Leading-Edge Separation

1985 ◽  
Author(s):  
Shawn H. Woodson ◽  
Fred R. DeJarnette
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Delta Wings ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Edge Separation

Interactive three-dimensional boundary-layer method for transonic flow over swept wings

AIAA Journal ◽  
1991 ◽  
Vol 29 (5) ◽  
pp. 678-679 ◽  
Author(s):  
Shawn H. Woodson ◽  
James F. Campbell ◽  
Fred R. DeJarnette
Keyword(s):  
Boundary Layer ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Swept Wings

A comparison of several eddy viscosity turbulence models in two and three dimensional boundary layer flows

1994 ◽  
Vol 98 (973) ◽  
pp. 73-82 ◽  
Author(s):  
A. W. C. Leung ◽  
L. C. Squire
Keyword(s):  
Boundary Layer ◽  
Eddy Viscosity ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Boundary Layer Flows ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Anisotropic Form

SummaryFour flow cases are calculated using a boundary layer method with five turbulence models. The Johnson-King model, in particular, is modified and two variant forms are used in the present work. The variant forms involve an anisotropic form of three-dimensional eddy viscosity formulations and a modification in the outer viscosity expression. It is found that the Johnson-King model generally performs very well as compared to the others, and the variant forms provide further improvement in most cases.

Experimental and Theoretical Investigation of the Supersonic Boundary Layer Stability on the Swept Wing

2008 ◽  
Vol 3 (3) ◽  
pp. 34-38
Author(s):  
Sergey A. Gaponov ◽  
Yuri G. Yermolaev ◽  
Aleksandr D. Kosinov ◽  
Nikolay V. Semionov ◽  
Boris V. Smorodsky
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Supersonic Boundary Layer ◽  
Mean Flow ◽  
Swept Wing ◽  
Wing Model ◽  
Dimensional Boundary ◽  
The Stability ◽  
Good Agreement

Theoretical and an experimental research results of the disturbances development in a swept wing boundary layer are presented at Mach number М = 2. In experiments development of natural and small amplitude controllable disturbances downstream was studied. Experiments were carried out on a swept wing model with a lenticular profile at a zero attack angle. The swept angle of a leading edge was 40°. Wave parameters of moving disturbances were determined. In frames of the linear theory and an approach of the local self-similar mean flow the stability of a compressible three-dimensional boundary layer is studied. Good agreement of the theory with experimental results for transversal scales of unstable vertices of the secondary flow was obtained. However the calculated amplification rates differ from measured values considerably. This disagreement is explained by the nonlinear processes observed in experiment

A Simple and Robust Subsonic Boundary Layer Method to Be Used with the Panel Method for Wing Calculations Using a Wing Strip Approach

2015 ◽  
Vol 798 ◽  
pp. 596-601
Author(s):  
R.F. Francisco Reis ◽  
Guilherme A. Santana ◽  
Paulo Iscold ◽  
Carlos A. Cimini
Keyword(s):  
Boundary Layer ◽  
Lift Coefficient ◽  
Aircraft Design ◽  
Aerodynamic Characteristics ◽  
Viscous Drag ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Classical Integral ◽  
Empirical Corrections

This paper will present the development of a simple subsonic boundary layer method suitable to be used coupled with panel methods in order to estimate the aerodynamic characteristics, including viscous drag and maximum lift coefficient, of 3D wings. The proposed method does not require viscous-inviscid iterations and is based on classical integral bi-dimensional boundary layer theory using Thwaites and Head ́s models with bi-dimensional empirical corrections applied to each wing strip being therefor robust and efficient to be used in the early conceptual stage of aircraft design. Presented results are compared to the Modified CS Method in an IBL scheme and experimental data and are shown to provide good results.

Prediction of Steady Propeller Performance with a Nonlinear Slipstream and Boundary-Layer Effect

1995 ◽  
Vol 39 (04) ◽  
pp. 297-312
Author(s):  
You-Hua Liu
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Leading Edge ◽  
Viscous Drag ◽  
Viscous Effects ◽  
Lattice Method ◽  
Suction Force ◽  
Layer Effect ◽  
Dimensional Boundary ◽  
Propeller Performance

Both slipstream deformation and viscous effects are factors that affect the performance of a rotating marine propeller but neither of them has been properly treated in most of the current lifting-surface methods and surface panel theories. With the introduction of a partial roll-up wake model that is flexible to various cases of propeller geometry and loading condition, this paper presents a vortex-lattice method that can improve propeller performance prediction especially at heavy loading conditions. Some observations on the calculation of the blade leading-edge suction force and how to deduct it to account for the viscous drag increasing are given. The scale effect of propeller performance can be readily predicted by the quasi-three-dimensional boundary-layer calculation presented in this paper. Some patterns of the limiting streamlines on blade surfaces are also illustrated and compared with experimental results.

Improved calculations of leading-edge separation from slender, thin, delta wings

1968 ◽  
Vol 306 (1484) ◽  
pp. 67-90 ◽  
Keyword(s):  
Boundary Layer ◽  
Leading Edge ◽  
Vortex Sheet ◽  
Lower Surface ◽  
Lateral Position ◽  
Quantitative Agreement ◽  
Delta Wings ◽  
Real Flow ◽  
Edge Separation ◽  
Secondary Separation

In previous calculations (Mangler & Smith 1959) of the vortex-sheet model of leading-edge separation, only qualitative agreement was found with experimental observations. Because the numerical treatment of the model was then necessarily incomplete, it was uncertain how far the lack of quantitative agreement was to be attributed to the limitations of the model. The use of an automatic digital computer has now made it possible to reduce the uncertainties in the calculation to a negligible level. The features of interest in the real flow are more accurately predicted and the remaining discrepancies can be ascribed to the deficiencies in the model. The paper describes the method used to locate the vortex sheet and determine its strength in terms of the two boundary conditions on it; assesses the credibility of the results; and relates them to the observations. It is concluded that the model successfully predicts the observed height of the vortex above the wing, though the predicted lateral position is in error by up to 6% of the semi-span of the wing. This error falls as the incidence increases and is less when transition occurs in the boundary-layer upstream of secondary separation. Normal force is predicted accurately as is the distribution of pressure on the lower surface and the inboard part of the upper surface. The observed suction peak below the vortex changes its character when transition occurs in the boundary-layer upstream of secondary separation. The model predicts the suction peak in the turbulent case fairly well, but it is clear that detailed prediction of the suction peak is not possible by a model which is wholly inviscid.

The three-dimensional laminar boundary layer on a flat plate

1965 ◽  
Vol 22 (3) ◽  
pp. 587-598 ◽  
Author(s):  
L. Sowerby
Keyword(s):  
Boundary Layer ◽  
Flat Plate ◽  
Three Dimensional ◽  
Leading Edge ◽  
Main Stream ◽  
Dimensional Parameter ◽  
Stress Components ◽  
Dimensional Boundary ◽  
Layer Flow ◽  
Limiting Streamlines

A series expansion is derived for the three-dimensional boundary-layer flow over a flat plate, arising from a general main-stream flow over the plate. The series involved are calculated as far as terms of order ξ2, where ξ is a non-dimensional parameter defining distance measured from the leading edge of the plate. The results are applied to an example in which the main stream arises from the disturbance of a uniform stream by a circular cylinder mounted downstream from the leading edge of the plate, the axis of the cylinder being normal to the plate. Calculations are made for shear stress components on the plate, and for the deviation of direction of the limiting streamlines from those in the main stream.

Receptivity mechanisms in three-dimensional boundary-layer flows

2009 ◽  
Vol 618 ◽  
pp. 209-241 ◽  
Author(s):  
LARS-UVE SCHRADER ◽  
LUCA BRANDT ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Free Stream ◽  
Three Dimensional ◽  
Leading Edge ◽  
Nonlinear Process ◽  
Transition To Turbulence ◽  
Boundary Layer Flows ◽  
Free Stream Turbulence ◽  
Dimensional Boundary ◽  
Layer Flow

Receptivity in three-dimensional boundary-layer flow to localized surface roughness and free-stream vorticity is studied. A boundary layer of Falkner–Skan–Cooke type with favourable pressure gradient is considered to model the flow slightly downstream of a swept-wing leading edge. In this region, stationary and travelling crossflow instability dominates over other instability types. Three scenarios are investigated: the presence of low-amplitude chordwise localized, spanwise periodic roughness elements on the plate, the impingement of a weak vortical free-stream mode on the boundary layer and the combination of both disturbance sources. Three receptivity mechanisms are identified: steady receptivity to roughness, unsteady receptivity to free-stream vorticity and unsteady receptivity to vortical modes scattered at the roughness. Both roughness and vortical modes provide efficient direct receptivity mechanisms for stationary and travelling crossflow instabilities. We find that stationary crossflow modes dominate for free-stream turbulence below a level of about 0.5%, whereas higher turbulence levels will promote the unsteady receptivity mechanism. Under the assumption of small amplitudes of the roughness and the free-stream disturbance, the unsteady receptivity process due to scattering of free-stream vorticity at the roughness has been found to give small initial disturbance amplitudes in comparison to the direct mechanism for free-stream modes. However, in many environments free-stream vorticity and roughness may excite interacting unstable stationary and travelling crossflow waves. This nonlinear process may rapidly lead to large disturbance amplitudes and promote transition to turbulence.

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