Effect of boattail angles on the flow pattern on an axisymmetric afterbody surface at low speed

Ambo, Takumi; Lee, Taekjin; Chen, Lin; Nonomura, Taku; Asai, Keisuke

doi:10.1016/j.expthermflusci.2018.07.034

Cited by 25 publications

(10 citation statements)

References 35 publications

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“…9) Additionally, at boattail angles larger than 20 , the flow is fully separated near the shoulder and drag increases. 14) Therefore, the minimum drag should exist at boattail angles between 10 and 20 . In our observation, the minimum drag occurred at a boattail angle around 14 , where the boattail pressure drag was well overcome by the low base drag.…”

Section: Total Aerodynamic Dragmentioning

confidence: 99%

“…Recently, Tran et al 14) was the first to report a type of transition flow between the attached and separated conditions. In that case, a separation bubble is generated near the boattail shoulder while massive separation is seen at the base edge.…”

Section: Introductionmentioning

confidence: 99%

“…19,20) The objective of this study is to investigate the effect of boattail angles on the pressure distribution and aerodynamic drag of axisymmetric models under low-speed conditions. Based on previous results of the skin friction, 14) three conical boattail models with angles of 10 , 14 and 20 were selected and tested. The flow behavior is characterized by the attached condition (10 ) and conditions with a separation bubble (14 and 20 ).…”

Section: Introductionmentioning

confidence: 99%

“…Azimuthal-averaged skin-friction distribution on boattail surfaces (Tran et al14) ). The skin-friction coefficient at x=L ¼ À0:12 was estimated using the empirical one-seventh power-law formula of Prandtl for a flat plate.…”

mentioning

confidence: 99%

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Effect of Boattail Angle on Pressure Distribution and Drag of Axisymmetric Afterbodies under Low-Speed Conditions

Ambo

Chen

Nonomura

et al. 2019

Trans. Japan Soc. Aero. S Sci.

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This study is focused on the effect of boattail angle on the pressure distribution and drag force of axisymmetric afterbodies under low-speed conditions. Experiments were conducted on three conical boattails with angles of 10°, 14°and 20°. The diameter-based Reynolds number is approximately 4.3 © 10 4 under the experimental conditions. Two types of flows, a fully-attached flow (¢ = 10°) and a flow with a separation bubble (¢ = 14°, 20°), were observed. The aerodynamic drag measurements were conducted using both a strut-supported model and a support-free (levitated) model. The results show that boattail model with the angle of 20°has a relatively large effect on the pressure distribution. The pressure drag resulting from pressure distribution on the vertical plane indicates that the model with a boattail angle of 14°has the lowest drag. A good trend in agreement between afterbody drag (measured using pressure taps) and total aerodynamic drag (measured using the levitated system) was obtained. The effect of strut support on pressure distribution at different polar angles is also explained in this study.

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Section: Total Aerodynamic Dragmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of Boattail Angle on Pressure Distribution and Drag of Axisymmetric Afterbodies under Low-Speed Conditions

Ambo

Chen

Nonomura

et al. 2019

Trans. Japan Soc. Aero. S Sci.

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“…Additionally, they showed that the turbulent intensity of the wake reduces with increasing boattail angle, whenever separation occurs on the boattail surface or not. Tran et al [11], who conducted experiments conical boattails with a small change of angles from 10°to 22°, observed three flow regimes on the boattail surface, which are attached flow, flow with separation bubble, and fully separated flow. However, the near-wake flow was not investigated in their study.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Boattail Angles on the Near-Wake Structure of Axisymmetric Afterbody Models at Low-Speed Condition

Tran

2020

International Journal of Aerospace Engineering

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The effect of a boattail angle on the structure of the wake of an axisymmetric model was investigated at low-speed condition. Four conical boattail models with angles of 0° (blunt-based body), 10°, 16°, and 22° were selected for this study. The Reynolds number based on the diameter of the model was around 1.97×104. Particle image velocimetry (PIV) was used to measure the velocity of the wake flow. The time-averaged flow characteristics including the length of recirculation of the afterbody, turbulent intensity, and Reynolds shear stress were analyzed and compared among those boattail models. The experimental results showed that the length of recirculation decreases with increasing boattail angle to 16°. At a boattail angle above 16°, the flow was fully separated near the shoulder and near-wake structure was highly changed. The turbulent intensity at a boattail angle of 22° showed a similar level to that in the case of the blunt-based body. Flow behavior on boattail surface should be accounted as an important parameter affecting the wake width and drag of the model. Power spectral density and proper orthogonal decomposition (POD) analyses showed that a Strouhal number of StD=0.2 dominated for the boattail model up to 16°. The fully separated flow was dominated by a Strouhal number of StD=0.03−0.06, which was firstly presented in this study.

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Determining Objects Surface and Its Characteristics by Mathematical Approach

Nguyen

Tran

2022

Lecture Notes in Mechanical Engineering

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Effect of boattail angles on the flow pattern on an axisymmetric afterbody surface at low speed

Cited by 25 publications

References 35 publications

Effect of Boattail Angle on Pressure Distribution and Drag of Axisymmetric Afterbodies under Low-Speed Conditions

Effect of Boattail Angle on Pressure Distribution and Drag of Axisymmetric Afterbodies under Low-Speed Conditions

The Effect of Boattail Angles on the Near-Wake Structure of Axisymmetric Afterbody Models at Low-Speed Condition

Determining Objects Surface and Its Characteristics by Mathematical Approach

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