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Tuesday, May 19, 2020 | History

3 edition of Acoustic effects on profile drag of a laminar flow airfoil found in the catalog.

Acoustic effects on profile drag of a laminar flow airfoil

John G. Shearin

Acoustic effects on profile drag of a laminar flow airfoil

by John G. Shearin

  • 158 Want to read
  • 10 Currently reading

Published by National Aeronautics and Space Administration, Langley Research Center, For sale by the National Technical Information Service in Hampton, Va, [Springfield, Va .
Written in English

    Subjects:
  • Sound.,
  • Laminar flow.

  • Edition Notes

    StatementJohn J. Shearin, Michael G. Jones, Robert A. Baals.
    SeriesNASA technical memorandum -- 100505.
    ContributionsJones, Michael G., Baals, Robert A., Langley Research Center.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL15281839M

      - Achieving laminar flow for some portion of the airfoil requires precise control/manufacture of the airfoil profile and surface smoothness. Impossible with a fabric wing, difficult with wood, challenging with thinner sheet aluminum, easier with composite surfaces.   My understanding is that, for airfoils, values less than , indicate laminar flow. I have tried using the Viscous-Laminar model in fluent, but it did not converge. I am beginning to have more success with the Spalart-Allmaras model, but now my lift values are 10% too low and drag 45% too high.

    Question: Laminar Flow Airfoils Have Improved Lift To Drag Characteristics In What AOA Regime? Improved Characteristics In All AOA Regimes Improved Characteristics In Low AOA Regimes Improved Characteristics In High AOA Regimes No Improved Characteristics With Respect To AOA. This flow pattern is quite similar to the one for laminar flow over a NACA 64A airfoil at α = 5 ∘ presented in Van Dyke’s album of fluid motion. For both airfoils the flow separates near the 50% chord location on the upper surface, and it leaves tangentially to the lower surface (Table 6).Cited by: 9.

    Wu et al. [16] investigated control effects on a NACA airfoil with a local unsteady forcing (% chord length width) located at 5% from the leading edge at the angle of attack from 18° to 35° with a File Size: KB. Set the airfoil angle of attack to 0°, and adjust the wind tunnel motor speed to achieve a Reynolds number of , (15 m/s free stream velocity). Details are specified in Step 2, Appendix B. With the flow and angle of attack set to the desired values, measure the lift .


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Acoustic effects on profile drag of a laminar flow airfoil by John G. Shearin Download PDF EPUB FB2

Get this from a library. Acoustic effects on profile drag of a laminar flow airfoil. [John G Shearin; Michael G Jones; Robert A Baals; Langley Research Center.]. The History of Laminar Flow The North American P Mustang was the first aircraft intentionally designed to use laminar flow airfoils.

However, wartime National Advisory Committee for Aeronautics (NACA) research data shows that Mustangs were not manufactured with a sufficient degree of surface quality to maintain much laminar flow on the wing. Acoustic flow control is investigated on the NACA laminar airfoil.

This airfoil has received considerable interest of late for its unique stall characteristics and the opportunities it. An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine), or sail (as seen in cross-section).

An airfoil-shaped body moving through a fluid produces an aerodynamic component of this force perpendicular to the direction of motion is called component parallel to the direction of motion is. A flight-test campaign of a supersonic natural laminar flow airfoil has been recently completed.

The test surface was an inch ( cm) chord and inch ( cm) span article mounted on the centerline store location of an FB airplane (McDonnell Douglas Corporation, File Size: 4MB.

In this study this effect has been used to reduce drag and increase lift of natural laminar flow airfoils at low Mach numbers with Reynolds numbers ranging from 3x, which is typical of long endurance unmanned aerial vehicles, to 6x typical of many general aviation aircraft.

Wing profile drag reduction of File Size: KB. NASA NLF(1) airfoil and those of the NACA airfoil at the cruise-flight Reynolds number is presented in Fig. The design goal of maintaining a broad lift range similar to that of the NACA airfoil has been achieved.

The low-drag benefit due to laminar flow is achieved over the cruise-flight lift-coefficient Size: KB. section of the airfoil is shown by the inset in the figure. Note that the curves are staggered. For Rc Z 35the CI curves are marked by a "sag" at low _.2 This is due to the laminar separation.

Note that at relatively higher _, the airfoil recovers to the high lift condition due to reattach-meritof the flow occurring naturally (Fig. ThisFile Size: KB. The present paper is devoted to the experimental study of the noise generated by an airfoil profile placed in a uniform laminar flow.

The far-field acoustic spectrum is shown to be composed of a broadband contribution around frequency f s and a discrete contribution at equidistant frequencies f n, which follow power laws of the forms f s ∼ U and f n ∼ U Cited by: This kind of airfoil is approximate to the laminar airfoil profile.

The laminar flow maintains more easily at low Reynolds number. Hence this kind of airfoil can extend the range of laminar flow to reduce drag forces. Download: Download full-size image; Fig.

Aerodynamic characteristics of airfoils at different locations with maximum Cited by:   In this study, the effects of acoustic excitation frequency on flow over an NACA airfoil were determined, and all of the experiments were done both with and without the presence of the acoustic excitation.

Our Undergraduate Project in Aeronautical Engineering Department (Tagore Engineering College) Delaying the Stall of an aerofoil wing by controlling the. NLF(1) (nlfil) NLF(1) - NASA/Langley/Somers-Selig-Maughmer NLF(1) natural laminar flow airfoil.

The 66 airfoil was designed to maintain laminar flow to the percen t- chord point, and the 63 was designed to maintain laminar flow to the percent-chord point. The designation system used for these airfoils, as well as older conventional NACA airfoil sections, is described in reference The two-element, slotted, natural-laminar-flow (SNLF) airfoil concept is a passive, NLF concept aimed at achieving a high maximum lift coefficient and extensive laminar flow in cruise [1].

The aft element allows favorable pressure gradients over the entire fore element, File Size: 1MB. ABSTRACT A matrix of airfoils has been developed to determine the effects of airfoil thickness and maximum lift on the sensitivity of the maximum lift to leading-edge roughness.

The matrix consists of three natural-laminar-flow airfoils, the S, S, and S, for wind. Laminar flow airfoils have less drag than conventional airfoil because a.) the adverse pressure gradient starts father back on the airfoil.

b.) and more of the airflow is laminar. EFFECTS OF LAMINAR 3 -TURBULENT TRANSITION ON BUFFET ONSET AND TRANSONIC CHARACTERISTICS OF LAMINAR AIRFOIL The results presented in this section were obtained for steady-flow conditions at angle of attack α=6 degrees and Mach number Ma=, in absence of oscillations of shockwave.

The transition is most conveniently observed as aFile Size: 1MB. [ ]6 Over a low Reynolds number airfoil, if the freestream turbulence intensity is low, flow starts as laminar; before transition the laminar boundary layer separates due to the adverse pressure gradient aft of the velocity peak.

The separated flow quickly undergoes transition to become turbulent. The present paper is devoted to the experimental study of the noise generated by an airfoil profile placed in a uniform laminar flow.

The far-field acoustic spectrum is shown to be composed of a. Aside from the review part, results of a comprehensive experimental study on the effects of acoustic flow control at low Reynolds numbers were presented. Within the scope of this experimental study, the effects of both parallel and perpendicular acoustic flow control were examined by means of pressure measurements, force measurements, hot-wire Cited by: 4.formation of an extensive laminar separation bubble on the airfoil surface.

Laminar separation has a significant detrimental effect on airfoil lift and drag. Therefore, improving airfoil performance is of interest. This can be accomplished by introducing a flow control mechanism that serves to .A Method of Quadrature for Calculation of the Laminar and Turbulent Boundary Layer in Case of Plane and Rotationally Symmetrical Flow.

NACA TM(Translated from Ingenieur-Archiv, Bd. 20, Heft 4,pp. –)Cited by: