국내 최대 기계 및 로봇 연구정보

공학설계D/B

공학설계D/B 게시판 내용
Volume Title	Aerodynamics
Volume No	BODIES - Drag (continued)
DATA Title	Normal force, pitching moment and side force of forebody-cylinder combinations for angles of attack up to 90 degrees and Mach numbers up to 5.
DATA Item	89014
KEYWORD	axisymmetric, blunt, body, cone, cylinder, ellipsoid, force, forebody, moment, normal, ogive, pitching, secant, sideforce, spherical, supersonic, tangent
ISBN	0 85679 686 7
ABSTRACT	ESDU 89014 provides a simple empirical method for estimating normal force and pitching moment. Although developed using wind-tunnel data for pointed and blunted tangent-ogive and cone-cylinders, and secant-ogive and ellipsoid-nosed cylinders, the method is applicable to any axisymmetric smooth forebody-cylinder combination. It requires as inputs the normal-force-curve and pitching-moment-curve slopes at zero angle of attack, which may be obtained from ESDU 89008, and simple geometric parameters that may be obtained from ESDU 77028. The method predicts normal force within 15 per cent at subsonic speeds but within 5 per cent at supersonic speeds, and predicts centre of pressure to within 5 per cent of body length. The range of data used in the correlation covered forebody fineness ratio of 0.75 to 6.28, overall body fineness ratio of 6 to 22.3 and Mach numbers from 0.27 to 4.5. The use of the method is illustrated by a worked example. The calculation procedure is programmed in ESDUpac A9034, see ESDU 90034. The effect of boat-tailing on normal force and pitching moment may be found from ESDU 87033. At high angles of attack, at subsonic and transonic Mach numbers, asymmetric vortex flow may occur on the leeward side of the body, creating an out-of-plane force distribution that may result in large sideforce and yawing moments and can also affect the normal force. The flow phenomena are considered and the local force distribution is illustrated. The influence of Reynolds number and nose blunting is considered and a discussion of Mach number effects is also given together with an envelope of maximum sideforce. The existence of various types of flow instability, depending on the Reynolds number/angle of attack combination, can affect the normal-force and pitching-moment predictions, and the region of applicability is illustrated and found to apply to the majority of the flight cases.