Laser-Doppler system for detection of aircraft trailing vortices
Carbon dioxide CW laser-Doppler velocimeter for detecting aircraft wing tip trailing vortices by measuring atmospheric aerosols backscatter
Huffaker, R. M.↗
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Vortices in separated flows
Vortices in axisymmetrically separated flows, comparing results of various experiments
Whitehead, A. H., Jr.↗
Atmospheric vorticity and dust devil rotation
Atmospheric vorticity and dust devil rotation direction relationship, suggesting shear in horizontal flows associated with convective activity in unstable atmosphere
Carroll, J. J.↗
Effect of interacting vortices on jet penetration into a supersonic stream
Interacting vortices effects on jet penetration into supersonic streams
Hersch, M.↗
Tip vortices - Velocity distributions
Flow field velocity distribution at rotating wing devices tip vortices
Chigier, N. A.↗
Nonlinear effects of the drift of buoyant vortices
Equation for motion of buoyant free vortices in inviscid fluid subjected to gravity
Costen, R. C.↗
An experimental investigation of trailing vortices behind a wing with a vortex dissipator
Trailing vortices behind wing tip with vortex dissipator, using wind tunnel flow visualization and flight tests
Chigier, N.↗
Solitary waves in concentrated vortices.
A nonlinear integrodifferential equation governing finite amplitude wave propagation on concentrated vortices is solved numerically. The solution to the Cauchy problem shows a solitary wave development qualitatively similar to solutions of the Korteweg-de Vries equation. A perturbation solution of the stationary form of the evolution equation confirms the unsteady calculation.
Leibovich, S.↗
Prediction of far flow field in trailing vortices.
A finite-difference machine code is brought to bear on the wake-vortex problem in the quasi-cylindrical boundary-layer approximation. A turbulent-energy model containing new features is developed. Parameters of the model are evaluated by comparison of calculated velocities and turbulent intensities with measurements in an axisymmetric wake. Comparisons are made with a previous calculation of the decay of an isolated vortex and with wind tunnel and flight measurements in trailing vortices. A self-similar solution develops at large axial distance that decays with the square root of distance. A slower decay occurs in the preceding transition region.
Baldwin, B. S.↗
The relationship between eddy-transport and second-order closure models for stratified media and for vortices
The question is considered of how complex a model should be used for the calculation of turbulent shear flows. At the present time there are models varying in complexity from very simple eddy-transport models to models in which all the equations for the nonzero second-order correlations are solved simultaneously with the equations for the mean variables. A discussion is presented of the relationship between these two models of turbulent shear flow. Two types of motion are discussed: first, turbulent shear flow in a stratified medium and, second, the motion in a turbulent line vortex. These two cases are instructive because in the first example eddy-transport methods have proven reasonably effective, whereas in the second, they have led to erroneous conclusions. It is not generally appreciated that the simplest form of eddy-transport theory can be derived from second-order closure models of turbulent flow by a suitably limiting process. This limiting process and the suitability of eddy-transport modeling for stratified media and line vortices are discussed.
Donaldson, C. D.↗
Decay of far flow field in trailing vortices
A finite-difference machine code is brought to bear on the wake-vortex problem in the quasi-cylindrical boundary-layer approxmation. A turbulent-energy model containing new features is developed that accounts for the major effects disclosed by more advanced models in which the parameters are not yet established. Several puzzles are resolved that arose in previous theoretical investigations of wake vortices.
Baldwin, B. S.↗
Laser Doppler velocimeter investigation of trailing vortices behind a semi-span swept wing in a landing configuration
Measured axial and tangential velocity profiles in the near wake vortices of a semi-span model of the Convair 990 wing in the NASA-Ames 7- by 10-foot wind tunnel are presented. A scanning laser Doppler velocimeter was used to obtain data at two different downstream stations (0.49 and 1.25 wing spans) at various angles of attack and configurations from wing alone to wing plus nacelles, anti-shock bodies, and flaps deflected 27 deg (landing configuration). It is shown that the velocity distributions within the wake are quite sensitive to span loading. Specifically, it is illustrated that an aircraft flying at given lift coefficient (C SUB L), can substantially reduce its trailing vortex upset potential by deploying its flaps and altering its flight attitude to maintain the same C SUB L. This might be taken into consideration along with performance and noise considerations in the selection of aircraft approach lift over drag.
Ciffone, D. L.↗
Lee-side vortices on delta wings at hypersonic speeds.
A fluid-dynamic investigation was carried out to determine the cause of intense heating observed on the lee meridian of hypersonic delta wings and also to derive means for its suppression. Several experimental techniques were combined with analysis of extensive heat-transfer measurements at a freestream Mach number of six in a range of Reynolds number to acquire a general description of the lee-flow structure. With attached leading-edge flow on the delta wings, the dominant feature is a pair of embedded vortices on the lee meridian whose interaction with the boundary-layer is responsible for the observed local heating. On the basis of flow visualization results and heat-transfer correlations, a qualitative vortex flow model is proposed which differs essentially from the conventional inboard separation vortex model.
Rao, D. M.↗
Decay of far flow field in trailing vortices
A finite difference machine code is used in the wake vortex problems in the quasi-cylindrical boundary layer approximation. A turbulent energy model containing new features is developed that accounts for the major effects disclosed by more advanced models in which the parameters are not yet established. Several puzzles that arose in previous theoretical investigations of wake vortices are resolved.
Baldwin, B. S.↗
Evaluation of effectiveness of various devices for attenuation of trailing vortices based on model tests in a large towing basin
The effectiveness of various candidate aircraft-wing devices for attenuation of trailing vortices generated by large aircraft is evaluated on basis of results of experiments conducted with a 0.03-scale model of a Boeing 747 transport aircraft using a technique developed at the HYDRONAUTICS Ship Model Basin. Emphasis is on the effects produced by these devices in the far-field (up to 8 kilometers downstream of full-scale generating aircraft) where the unaltered vortex-wakes could still be hazardous to small following aircraft. The evaluation is based primarily on quantitative measurements of the respective vortex velocity distributions made by means of hot-film probe traverses in a transverse plane at selected stations downstream. The effects of these altered wakes on rolling moment induced on a small following aircraft are also studied using a modified lifting-surface theory with a synthesized Gates Learjet as a typical example. Lift and drag measurements concurrently obtained in the model tests are used to appraise the effects of each device investigated on the performance characteristics of the generating aircraft.
Kirkman, K. L.↗
Separated flow over bodies of revolution using an unsteady discrete-vorticity cross wake. Part 2: Computer program description
A method is developed to determine the flow field of a body of revolution in separated flow. The computer was used to integrate various solutions and solution properties of the sub-flow fields which made up the entire flow field without resorting to a finite difference solution to the complete Navier-Stokes equations. The technique entails the use of the unsteady cross flow analogy and a new solution to the two-dimensional unsteady separated flow problem based upon an unsteady, discrete-vorticity wake. Data for the forces and moments on aerodynamic bodies at low speeds and high angle of attack (outside the range of linear inviscid theories) such that the flow is substantially separated are produced which compare well with experimental data. In addition, three dimensional steady separated regions and wake vortex patterns are determined. The computer program developed to perform the numerical calculations is described.
Marshall, F. J.↗
Separated flow over bodies of revolution using an unsteady discrete-vorticity cross wake. Part 1: Theory and application
A method is developed to determine the flow field of a body of revolution in separated flow. The technique employed is the use of the computer to integrate various solutions and solution properties of the sub-flow fields which made up the entire flow field without resorting to a finite difference solution to the complete Navier-Stokes equations. The technique entails the use of the unsteady cross flow analogy and a new solution to the required two-dimensional unsteady separated flow problem based upon an unsteady, discrete-vorticity wake. Data for the forces and moments on aerodynamic bodies at low speeds and high angle of attack (outside the range of linear inviscid theories) such that the flow is substantially separated are produced which compare well with experimental data. In addition, three dimensional steady separation regions and wake vortex patterns are determined.
Marshall, F. J.↗
Apparent relationship between solar-sector boundaries and 300-mb vorticity: Possible explanation in terms of upward propagation of planetary-scale waves
The selection process for sector structure boundary crossings used in vorticity correlation studies is examined and the possible influence of ascending planetary scale waves is assessed. It is proposed that some of the observed correlations between geomagnetic and meteorological variations may be due to meteorological effects on the geometric variables, rather than due to common solar origin.
Deland, R. J.↗