6926475988

Kry Word*: Axial forer. Harmonie responae

Kay Word*: Airfoil*, Fluid-inducad excitation. Stalling

Kay Word*: AlrfoHt. Fluid-inducad axcitation. Wind-inducad *xcłtatk>n, Stalling

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84*1782

On the Effect of AxiaJ Compreasion on the Bouad* of Simple Harmonie Motion

V. Birman. I. Elishakoff, and J. Singer Dept. of Aeronautical Engrg.. Technion •• Israel Inst. of Tech., Haifa. Israel, Israel J. Tech.. 20 (6), pp 254-267 0982) 13 figs. 16refs

Nonlinear for cod motion of on*-degree-of-fre#dom statically compresaad tyittm* with cubic nonlinaarity i* studiad. An approximata analytical eritarion is empłoyed to a«tab//*h tha boundi of driving force frequencie* corra«x>nding to tha domination of limpfe harmonie motion. Thaaaanałytical boundi ara comparad with tho*a ob ta i nad by numarical intagration.

84-1783

Contmued ExperiroenUl lnvestigatk>n of Dynamie Stall

S.J. Schreck

Air Force Inst. of Tech.. Wright-Patterson AFB, OH, Rept. No. AFIT/GAE/AA/83D-21, 147 pp (Dec 1983)

AD-A136 920

Flow ovar an airfoił undergoing a conttant rata of changa of angla of attack wa* experimantally ctudiad ov*r a ranga of tunnal tp—d* and rotation rata*. Surface pressure tran*-ducar* couplad with a microcomputer-bated data acqui*łtk>n tystam wara utad to cołlect turface-presaure data at tha rat* of 4000 ampla* par second; data raduction was al*o m icrocomput er based.

84-1784

hnreatigation of Effect* Contributing to Dynamie Stall Uamg a Momentum-bategral Method

J.S. Lawrence

School of Engrg., Air Force Inst. of Tech., Wright-Patterson AFB. OH. Rept. No. AFIT/GAE/AA/83D* 12.108 pp (Dec 1983)

AD-A136 897

Dynamie stall effect i ara analyzed in this imrettigation for casas of an inartielly itatic airfoil in a fk>w field rotating at constant rata (gust reiponse), and an airfoil pitching at constant rata In a staady fIow field. Tha method uaed is a boundary layer tolution of the momentum-integral equation by a modified von Karman-Pohlhausan tachnique. Frevious work u ling thi* method to match Kramer'* experimental reiults for gust radonie is rayiawed, corrected. and eon-tinuad. Th* validity of tha clotura equation and the assump-tions kay to its darivation ara axaminad.

84-1785

Airfoil Shape and Thickneaa Effect a on Tranaonie Airloads and Flutter

S.R. Bland and J.W. Edwards

NASA Langley Res. Ctr., Hampton, VA. J. Aircraft,

21 (3). pp 209-217 (Mar 1984) 14 figs. 12 refs

Kay Word*: Airfoil*. Geometrie effects, Flutter

A tramient pul*e technique is uied to obtain harmonie force* from a tlma-marchlng solution of the complete unstaady transonic imall-parturbation potential equation. Tha unstaady pressures and forcas acting on a model of tha NACA 64A010 conventional airfoil and the MBB A-3 supercritical airfoil ovar a ranga of Mach numbers ara axamined in detail.

84-1786

On the Dynamie Beh*vtor of the Wobbleatone

R.E. Lindberg, Jr. and R.W. Longman Aerospace Syst. Div., Naval Res. Lab., Washington, DC 20375. Acta Mech.. 4£ (1/2). pp 81-94 (1983) 10 figs. 5 refs

Kay Words: Rotating structuras, Vibration retponte

Tha wobblastone is a ganaralizad form of a top with distinct inertias and a non*>herical surface at the point of oontact to tha horizontal piana on which It mov*s. Some wobbta-stones axhibrt a curious propany of allowing staady rotation about tha v*rtical Principal inartia axis only when rotatad in ona diraction, whil* othar wobblastone* axhibit rapaatad rayaraals of tha diraction of rotation aftar baing spun. Non-llneer equatk>n* govarning tha motion of • wobblastone ara d*rłv*d assumlng no slippage at tha point of oontact to the supporting rlgid piana, which corra*x>nd» to a conservative model. Tha *quations ara formulatad in a mannar auitabl* for numarical intagration. Tha major ob*erv*d propanie* of tha motion of thaaa asymmetrical top* ar* demonstrated in numarical simuiations.

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