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Computation of Stiffness and Damping Derivatives of an Ogive in a Limiting Case of Mach Number and Specific Heat Ratio
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作者 Aysha Shabana Asha Crasta +2 位作者 Sher Afghan Khan Abdul Aabid Muneer Baig 《Fluid Dynamics & Materials Processing》 EI 2023年第5期1249-1267,共19页
This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity.In such conditions,these stability derivatives depend on the Ogive’s shape and not the Mach numbe... This work aims to compute stability derivatives in the Newtonian limit in pitch when the Mach number tends to infinity.In such conditions,these stability derivatives depend on the Ogive’s shape and not the Mach number.Generally,the Mach number independence principle becomes effective from M=10 and above.The Ogive nose is obtained through a circular arc on the cone surface.Accordingly,the following arc slopes are consideredλ=5,10,15,−5,−10,and−15.It is found that the stability derivatives decrease due to the growth inλfrom 5 to 15 and vice versa.Forλ=5 and 10,the damping derivative declines with an increase inλfrom 5 to 10.Yet,for the damping derivatives,the minimum location remains at a pivot position,h=0.75 for large values ofλ.Hence,whenλ=−15,the damping derivatives are independent of the cone angles for most pivot positions except in the early twenty percent of the leading edge. 展开更多
关键词 Aerodynamic stability derivative Mach number specific heat ratio ogive
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Meaning of an Ogive by Students of Diploma in Accountancy in an Institute of Higher Education
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作者 Sharida Hashim Nik Azis Nik Pa 《Open Journal of Statistics》 2014年第2期137-143,共7页
The study based on radical constructivism seeks to identify Semester Two Accounting Courses students’ meaning of ogive. Data for this study include verbal and non-verbal information gathered from three students of Se... The study based on radical constructivism seeks to identify Semester Two Accounting Courses students’ meaning of ogive. Data for this study include verbal and non-verbal information gathered from three students of Semester Two Accounting Courses in clinical interview sessions. The research participants have identified four processes performed on the basic elements to produce an ogive. In addition, five categories of products used by research participants to describe the ogive were identified. 展开更多
关键词 ogive MEANING in Mathematics Radical CONSTRUCTIVISM Clinical Interview
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Effect of multiple rings on side force over an ogive-cylinder body at subsonic speed
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作者 Priyank KUMAR J.K.PRASAD 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第6期1181-1188,共8页
Experiments and computations were performed over an ogive-cylinder body having an lift-to-drag ratio of 16 at a diameter Reynolds number of 29000. The side force on the slender body augments with increasing angles of ... Experiments and computations were performed over an ogive-cylinder body having an lift-to-drag ratio of 16 at a diameter Reynolds number of 29000. The side force on the slender body augments with increasing angles of attack for the case without a ring. This increase was mainly due to the increase in the asymmetry of the existing vortex pair in the wake of the body. Attempts were made to completely reduce the existing side force at the angle of attack ranging from 35° to 45°.Three rectangular cross-sectioned circumferential rings having a height of 3% of the local diameter were placed at axial distances of 2.5, 3.5 and 4.5 times the base diameter from the tip of the body so as to reduce the side force. The results obtained indicate that inclusion of three rings completely alleviated the side force on the slender body at the angle of attack ranging from 0° to 45°. The presence of rings was found to alter the growth of the vortices that helped in the reduction of the side force. Computations performed were in reasonable agreement with the experiments. 展开更多
关键词 Asymmetric vortex High angle of attack ogive Side force Slender body Vortex lift
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低风速涌浪条件下浪致应力的研究
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作者 潘伟 邹仲水 +1 位作者 宋金宝 黄健 《海洋学报》 CAS CSCD 北大核心 2021年第10期1-9,共9页
本文基于2012年2月15日至5月8日的广东省茂名市附近海上铁塔实测数据,分析了海气边界层的湍流运动。结果证实,在涌浪条件下,协谱和Ogive曲线存在明显受涌浪影响的区域。本文进一步研究,发现浪致雷诺应力的正负符号变化与波龄相关,并给... 本文基于2012年2月15日至5月8日的广东省茂名市附近海上铁塔实测数据,分析了海气边界层的湍流运动。结果证实,在涌浪条件下,协谱和Ogive曲线存在明显受涌浪影响的区域。本文进一步研究,发现浪致雷诺应力的正负符号变化与波龄相关,并给出了顺风向和侧风向浪致雷诺应力正负符号反转时波龄的统计分布。此外,本文基于协谱法提取了浪致雷诺应力τ_(swell),并与传统方法得到的浪致雷诺应力τ_(*swell)做比较。结果表明,整体上τ_(swell)比τ_(*swell)大2~3个量级,这意味着传统方法显著低估了涌浪的浪致雷诺应力,传统的浪致雷诺应力计算方法还有待改进。 展开更多
关键词 涌浪 浪致雷诺应力 协谱 ogive曲线
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