Vol.3, No 12, 2002 pp. 371-382
UDC 533.6.07:533.69.04

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ON THE INFLUENCE OF SPIKE SHAPE
AT SUPERSONIC FLOW PAST BLUNT BODIES
Snežana S. Milićev¹, Miloš D. Pavlović¹, Slavica Ristić², Aleksandar Vitić^2
1University of Belgrade, Faculty of Mechanical Engineering
27 marta 80, 11000 Belgrade, Yugoslavia, e-mail: milpav@alfa.mas.bg.ac.yu
²Technical Institute of the Yugoslav Army, Katanićeva 15, 11000 Belgrade, Yugoslavia

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In order to eliminate the appearance of a strong shock wave at a supersonic flight of a missile, which considerably increases the drag during its flight through the air, a spike is mounted on its nose. Presented paper offers the results of an experimental analysis of the influence of the spike's shape on the aerodynamic coefficients (drag, lift and pitching moment coefficient, as well as the location of the center of pressure) at supersonic flow past blunt-nosed body. The experiment was carried out in a wind tunnel, for one value of Mach and Reynolds numbers, and for one value of the angles of attack, alpha = 2^o. For the body without spike, and with four different spike shapes, the aerodynamic forces and moment were measured. Using only the photos obtained by Schlieren visualization of the flow, the paper proposes a criterion of estimating the aerodynamic effect of the spike shape. The best spike shape from the experimental set of spikes, selected by the measurement of the aerodynamic coefficients, coincided with this qualitative criterion.
Key words:  blunt-nosed body, spiked body, supersonic flow, shock wave, angle of attack, aerodynamic coefficients.

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O UTICAJU IGLE NA NADZVUČNO STRUJANJE OKO ZAOBLJENOG TELA Da bi se eliminsala pojava jakog udarnog talasa pri nadzvučnom opstrujavanju projektila, koja zanačajno povećava otpor pri letu krozvazduh, na njegov vrh montira se igla. U radu se daju rezultati eksperimentalnog istraživanja uticaja oblika igle na aerodinamičke koeficijente (uzgona, otpora, momenta propinjanja, kao i položaj centra pritiska) pri nadzvučnom opstrujavanju tela zaobljenog vrha. Eksperiment je izveden u aereotunelu, za jednu vrednost Mahovog i Rejnoldsovog broja, kao i za jednu vrednost napadnog ugla alpha = 2^o. Za telo bez igle, kao i za telo sa četiri različita modela igle merene su aerodinamičke sile i momenti. U radu su predloženi kriterijumi za procenu uticaja igle zasnovani isključivo na rezultataima dobijrenim vizualizacijom strujanja. Igla najboljih karakteristika, od ispitanih konfiguracija, izabrana na osnovu izmerenih aerodinamičkih koeficijenata, uklapa se u ove kvalitativne kriterijume.