Breathing blunt-nose concept for drag reduction in supersonic flow

Vashishtha, Ashish; Rathakrishnan, E.

doi:10.1243/09544100jaero369

Cited by 9 publications

(5 citation statements)

References 3 publications

(2 reference statements)

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“…These kind of deformed shocks were found to be weaker than the shock at the model without nose hole, by Ashish and Rathakrishnan. 4 In accordance to this argument, for the present case also, it can be stated that the breathing nose reduces the strength of the bow shock at the model nose, and this can be taken as an advantage, since weakening the shock would result in reduced pressure over the nose of the model. This reduction in the positive pressure would result in reduction of drag, caused by the compression of the flow by the shock.…”

Section: Resultssupporting

confidence: 77%

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Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

Watanabe

Suzuki

Rathakrishnan

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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Breathing blunt nose technique is one of the promising methods for reducing the drag of blunt-nosed body at hypersonic speeds. The air, traversed by the bow shock positioned ahead of the nose, at the stagnation region is allowed to enter through a hole at the blunt-nose and ejected at the rear part (base region) of the body. This manipulation reduces the positive pressure over the stagnation regions of the nose and increases the pressure at the base, resulting in reduced suction at the base. The simultaneous manifestation of reducing the compression at the nose and suction at the base regions results in reduction of the total drag. The drag reduction caused by the breathing blunt nose technique has been measured in a Mach 7 tunnel. Also, the drag and flow field around the blunt-nosed body, with and without breathing hole, has been computed. The aerodynamic characteristics of the breathing blunt nose model obtained experimentally are compared with the CFD results. It is found that the breathing results in 5% reduction in drag. The lift coefficient also comes down for the model with breathing nose. But the lift-to-drag ratio is found to be the same for both the cases; the blunt-nosed body with and without nose-hole.

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Section: Resultssupporting

confidence: 77%

“…Drag reduction caused by BBN at Mach 1.96 flow was experimentally investigated by Ashish et al. 4 In Mach 1.96 flow, the BBN method was found to be effective in reducing drag force. The drag coefficient with BBN method was found to be 21% smaller than that of the body without a hole.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

Watanabe

Suzuki

Rathakrishnan

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Among them, mechanical spike is a passive drag control method and counterjet flow and energy deposition are active drag control methods. Breathing blunt nose is another passive drag control methods studied in supersonic [3] and hypersonic [4] flow regimes. The majority of the drag control methods work by manipulation of the frontal shock wave either by pushing away from the body as in the case of spike, counterjet flow and energy deposition or bringing closer the frontal shock and manipulating the base drag in breathing blunt nose.…”

Section: Introductionmentioning

confidence: 99%

Drag Control by Hydrogen Injection in Shocked Stagnation Zone of Blunt Nose

Vashishtha,

Callaghan,

Nolan

2020

Preprint

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The main motivation of the current study is to propose a high-pressure hydrogen injection as an hybrid active flow control technique in order to manipulate the flow-field in front of a blunt nose during hypersonic flight. Hydrogen injection can lead to self-ignition under the right environment conditions in a stagnation zone, and may cause thermal heat addition through combustion and provide the counterjet effect together by pushing bow shock upstream. The axisymmetric numerical simulations for the hemispherical blunt nose are performed at a Mach 6 freestream flow with 10000 Pa pressure and 293 K temperature. The sonic and supersonic hydrogen and air injections are compared for drag reduction at the same stagnation pressure ratio P R and momentum ratio (RMA). The sonic air and hydrogen injection scenarios show similar performance in terms of drag reduction and similar SPM flow features, but hydrogen injection has a mass flow rate 3.76 times lower than air. Supersonic hydrogen injection at Mj 2.94 behaves differently than supersonic air injection and can achieve up to 60 % drag reduction at lower PR and LPM mode with lower mass flow rate. Additionally, air injection achieves a drag reduction of 40 % in SPM mode at higher PR with very high mass flow rate.

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“…6) Further the effectiveness of BBN on drag reduction has been studied at supersonic speed by Ashish et.al. 7) The performance of disk-band-gap parachute model has been studied by Wernet et.al. 8) for supersonic parachute model.…”

Section: Introductionmentioning

confidence: 99%

Bow-Shock Instability and its Control in front of Hemispherical Concave Shell at Hypersonic Mach Number 7

Vashishtha

Watanabe

Suzuki

2016

AEROSPACE TECHNOLOGY JAPAN

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In this study, effectiveness of vortex manipulation by using passive control methods at hypersonic flows have been studied to control the bow-shock instabilities in front of negative curvature (concave) hemispherical shell. The force measurement and unsteady center pressure measurements were performed for hemispherical shell with no control and with three kind of passive controls such as spike at the center of cavity, breathing holes at the curved surface and crosswire along the diameter of hemisphere. The flow visualization for shock instability in front of all four geometries were performed using twin mirror Schlieren system and high-speed camera with 10,000 fps, which were synchronized with pressure measurements. The fluctuations in bow-shock were computed in time resolved manner by image processing methods and compared with pressure data. It is found that drag coefficient does not change significantly by using the different control methods, which were studied. The time resolved Schlieren image processing method is reliable in providing the information of shock fluctuations and the crosswire control method is most effective in subsiding the large shock deformation in the current study.

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Breathing blunt-nose concept for drag reduction in supersonic flow

Cited by 9 publications

References 3 publications

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

Drag Control by Hydrogen Injection in Shocked Stagnation Zone of Blunt Nose

Bow-Shock Instability and its Control in front of Hemispherical Concave Shell at Hypersonic Mach Number 7

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