Boattail and base pressure prediction including flow separation for afterbodies with a centered propulsive jet and supersonic external flow at small angles of attack

The nanosecond plasma discharge actuator driven by high voltage pulse with typical rise and decay time of several to tens of nanoseconds is emerging as a promising active flow control means in recent years and is being studied intensively. The characterization study reveals that the discharge induced shock wave propagates through ambient air and introduces highly transient perturbation to the flow. On the other hand, the residual heat remaining in the discharge volume may trigger the instability of external flow. In this study, this type of actuator is used to suppress flow separation over a ramp model. Numerical simulation is carried out to investigate the interaction of the discharge induced disturbance with the external flow. It is found that the flow separation region over the ramp can be reduced significantly. Our work may provide some insights into the understanding of the control mechanism of nanosecond pulse actuator.

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Characteristics of base pressure fluctuations of a typical missile configuration with a propulsive jet

Aerospace Science and Technology ◽

10.1016/j.ast.2017.10.021 ◽

2017 ◽

Vol 71 ◽

pp. 695-705 ◽

Cited By ~ 2

Author(s):

M. Viji ◽

N.S. Vikramaditya ◽

S.B. Verma ◽

Naveed Ali ◽

D.N. Thakur

Keyword(s):

Pressure Fluctuations ◽

Base Pressure ◽

Propulsive Jet

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Optimization of Drag Minimums Including Effects of Flow Separation

Journal of Engineering for Industry ◽

10.1115/1.3438136 ◽

1973 ◽

Vol 95 (1) ◽

pp. 360-364 ◽

Cited By ~ 6

Author(s):

A. L. Addy ◽

R. A. White

Keyword(s):

Recent Work ◽

Flow Separation ◽

Design Consideration ◽

Jet Interaction ◽

Pressure Drag ◽

Wide Range ◽

Flight Profile ◽

Interaction Problem ◽

Propulsive Jet

Recent work on the supersonic freestream-centered propulsive jet interaction problem has shown that minimum total afterbody drag can be achieved during power on flight with less than a full (zero annular base) boattail. In contrast to optimum power-on configurations, minimum total afterbody pressure drag for power-off (coast) flight requires, in general, a full boattail. Flow separation of the freestream on the boattail is known to occur for a wide range of flight conditions during power-on operation. This flow separation is shown herein to reduce total afterbody drag for nearly full boattails to values which approach the corresponding values for optimized configurations without separation. Thus, the possibility of reconciling flight-profile drag minimums for both power-on and power-off conditions by using afterbody separation is suggested and shown to be a feasible design consideration.

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Investigation of Three-Dimensional Internal and External Flow Separation

2010 DoD High Performance Computing Modernization Program Users Group Conference ◽

10.1109/hpcmp-ugc.2010.10 ◽

2010 ◽

Author(s):

A. Gross ◽

R. Jacobi ◽

H. Fasel

Keyword(s):

Flow Separation ◽

Three Dimensional ◽

External Flow

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Direct STEM ADF imaging of gold on silicon (111)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154330 ◽

1989 ◽

Vol 47 ◽

pp. 472-473

Author(s):

P. Xu ◽

E. J. Kirkland ◽

J. Silcox

Keyword(s):

Film Growth ◽

Heavy Atom ◽

High Vacuum ◽

Dark Field ◽

Thin Metal Film ◽

Base Pressure ◽

Ultra High Vacuum ◽

Specimen Preparation ◽

Dark Field Imaging ◽

Wide Range

Many studies of thin metal film growth and the formation of metal-semiconductor contacts have been performed using a wide range of experimental methods. STEM annular dark field imaging could be an important complement since it may allow direct imaging of a single heavy atom on a thin silicon substrate. This would enable studies of the local atomic arrangements and defects in the initial stage of metal silicide formation.Preliminary experiments were performed in an ultra-high vacuum VG HB501A STEM with a base pressure of 1 × 10-10 mbar. An antechamber directly attached to the microscope for specimen preparation has a base pressure of 2×l0-10 mbar. A thin single crystal membrane was fabricated by anodic etching and subsequent reactive etching. The specimen was cleaned by the Shiraki method and had a very thin oxide layer left on the surface. 5 Å of gold was deposited on the specimen at room temperature from a tungsten filament coil monitored by a quartz crystal monitor.

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